Author name code: cook ADS astronomy entries on 2022-09-14 author:"Cook, John W." ------------------------------------------------------------------------ Title: Latest Results from NASA Ames' COSmIC and Optical Constants Facility: Determining Optical Constants for Titan, Pluto and Protoplanetary Disks Applications Authors: Sciamma-O'Brien, E.; Roush, T.; Salama, F.; Bertrand, T.; Cook, J.; Dalle Ore, C.; Cruikshank, D.; Grundy, W.; Mastrapa, R. Bibcode: 2021AAS...23821201S Altcode: The NASA Ames COsmic SImulation Chamber (COSmIC) is a unique experimental facility that can be used, among many applications, to produce solid particles from gas phase molecular precursors at low temperature (150 K) using a plasma discharge to induce the chemistry in the stream of a free jet expansion. The choice of the initial gas mixture used to produce the solid sample allows the simulation of either cold planetary atmospheres like Titan or Pluto (with N2/CH4-based initial mixtures), or circumstellar environments (with Ar/CxHy-based initial mixtures).

The Ames Optical Constants Facility (OCF) allows the determination of optical constants covering a broad wavelength range with high spectral resolution for solid materials, analogs of organic refractory materials formed in planetary and astrophysical environments. The core of the OCF is a Fourier transform infrared (FTIR) spectrometer that allows the continuous characterization of solid samples in the visible to far-infrared (FIR) range (0.59-200 μm, 16,950-50 cm−1). Modeling of the laboratory measurements conducted with the OCF allows the determination of accurate optical constants, n and k, over the full vis-FIR range.

Here we present the latest results of two studies that combined (1) experiments performed with COSmIC to produce analogs of aerosols forming in Titan's atmosphere and analogs of cosmic grains forming in circumstellar envelops, and (2) the characterization of these analogs with the OCF to provide the real and imaginary parts of their refractive indices, n + ik, to the community, from the visible to the FIR. These optical constants can be used as critical input parameters in radiative transfer, atmospheric and reflectance models to interpret observational data of, e.g., Titan's atmosphere and protoplanetary disks. Providing optical constants for various materials of different compositions allows to explore a broad range of composition by simulating mixtures of materials. We also present a new project to produce analogs of Pluto's atmospheric aerosols with COSmIC and determine their optical constants with OCF, to be used in reflectance spectra models for the interpretation of New Horizons observations of Lowell Regio, Sputnik Planitia and Cthulhu. Title: A comparison of BAA Solar Section white-light measurements Authors: Meadows, P.; Smith, L.; Cook, J. Bibcode: 2021JBAA..131...22M Altcode: This paper compares the BAA white-light measurements made during Solar Cycle 24. The main purpose is to assess whether there are any differences in the recorded long-term characteristics of solar activity for observers who determine the number of groups, the sunspot number and/or the BAA quality number (based on type of group). A comparison is also performed between the International Sunspot Number and the BAA sunspot number. Title: Notes and News: The Radio Astronomy Section in 2019 Authors: Cook, J. Bibcode: 2020JBAA..130...74C Altcode: No abstract at ADS Title: Titan tholin like materials across the surface of Pluto Authors: Protopapa, S.; Olkin, C.; Grundy, W.; Li, J.; Verbiscer, A.; Gautier, T.; Cook, J.; Reuter, D.; Howett, C.; Stern, A.; Beyer, R.; Porter, S.; Young, L.; Weaver, H.; Ennico, K.; Dalle Ore, C.; Quirico, E.; Scipioni, F.; Singer, K. Bibcode: 2020AAS...23543803P Altcode: Pluto presents in enhanced visible color images acquired with the New Horizons' Multi-spectral Visible Imaging Camera (MVIC, Reuter et al. 2008) a wide range of colors from vivid red, brown, to yellow colors, highly correlated with Pluto's varied underlying geological structures (Stern et al. 2015; Olkin et al. 2017). The color contrast is less obvious in natural-color images. Tholins, which are the refractory residues obtained from the irradiation of gases and ices containing hydrocarbons (Cruikshank 2005), are thought to be present on the surface of Pluto, serving as coloring agents (e.g., Stern et al. 2018). However, the number of distinct types of tholins on the surface of Pluto, and the processes responsible for their formation and distribution remains subject of investigation. We investigate this problem by means of 1) a multi-wavelength, regionally dependent photometric analysis of Pluto's encounter hemisphere using the color images collected by the Ralph/MVIC instrument on board of New Horizons at four visible wavelengths from 400 nm to 910 nm and 2) analysis, using a multiple-scattering radiative transfer model (Hapke, 2012), of combined MVIC and LEISA (a mapping infrared composition spectrometer covering the wavelength range 1.25-2.50 µm) spectra of eastern Cthulhu and Lowell Regio. Cthulhu and Krun Maculae are significantly darker and redder than the rest of the surface. Regions dominated by volatile ices such as the yellow material across Pluto's north pole observed in enhanced color images present single scattering albedos of ∼ 0.98 or higher, and almost neutral across the visible wavelength range. This result indicates a very limited contribution of tholin materials on the optically active surfaces in these regions. We use a tholin material with optical constants very similar to that of Titan tholin by Khare et al. (1984) to reproduce the spectral properties of these two regions with such diverse coloration, compositions, morphologies, and ages. Because a single pigment can be used to account for all of Pluto's colors and this is consistent with a Titan tholin like material, we concur with the idea suggested first by Grundy et al. (2018) that Pluto's coloration is the result of photochemical products mostly produced in the atmosphere. Although cosmic rays and ultraviolet photons at wavelengths longer than 145 nm do reach Pluto's surface, and can be expected to drive chemical processing there, the observations of diverse colors do not require different chemical products to be responsible for the colors in different environments. Title: The larger sunspot groups of Cycle 24 Authors: Meadows, P.; Smith, L.; Cook, J. Bibcode: 2019JBAA..129..222M Altcode: Using observations submitted to the BAA Solar Section, the largest sunspot groups of Solar Cycle 24 are discussed and example images shown. The characteristics of the cycle are also described and a comparison is made between the sizes of its larger sunspot groups and those of previous cycles, stretching back over 100 years. Title: Traverses for the ISECG-GER design reference mission for humans on the lunar surface Authors: Allender, Elyse J.; Orgel, Csilla; Almeida, Natasha V.; Cook, John; Ende, Jessica J.; Kamps, Oscar; Mazrouei, Sara; Slezak, Thomas J.; Soini, Assi-Johanna; Kring, David A. Bibcode: 2019AdSpR..63..692A Altcode: This study explores the Design Reference Mission (DRM) architecture developed by Hufenbach et al. (2015) as a prelude to the release of the 2018 Global Exploration Roadmap (GER) developed by the International Space Exploration Coordination Group (ISECG). The focus of this study is the exploration of the south polar region of the Moon, a region that has not been visited by any human missions, yet exhibits a multitude of scientifically important locations - the investigation of which will address long standing questions in lunar research. This DRM architecture involves five landing sites (Malapert massif, South Pole/Shackleton crater, Schrödinger basin, Antoniadi crater, and the South Pole-Aitken basin center), to be visited in sequential years by crew, beginning in 2028. Two Lunar Electric Rovers (LER) are proposed to be tele-robotically operated between sites to rendez-vous with crew at the time of the next landing. With engineering parameters in mind we explore the feasibility of tele-robotic operation of these LERs between lunar landing sites, and identify potential high interest sampling locations en-route. Additionally, in-depth sample collection and return traverses are identified for each individual landing site across key geologic terrains that also detail crew Extra-Vehicular Activity (EVA). Exploration at and between landing sites is designed to address a suite of National Research Council (2007) scientific concepts. Title: The Radio Astronomy Group in 2017 Authors: Cook, J. Bibcode: 2018JBAA..128..116C Altcode: No abstract at ADS Title: LIGO/Virgo G298048: Zadko Telescope 7 day observations of the OT candidate SSS17a/DLT17ck Authors: Coward, D.; Howell, E.; Laugier, R.; Klotz, A.; Boer, M.; Andreoni, I.; Cook, J.; Macpherson, D.; Moore, J.; Burrell, A.; OzGrav; TZAC Bibcode: 2017GCN.21744....1C Altcode: We report 7 days of Zadko Telescope imaging of the transient SSS17a/DLT17ck in NGC4339 started on 2017-08-19 10:57 UT (t0+2 days). We use the stacked image of the night 201-08-26 (t0+9 days) as a mask to substract the light contribution from the galaxy NGC 4993 and synthesise one residual image for each nights observation. Photometry is performed using the star NOMAD-1 0666-0296321 for PSF fitting. The complete log of Zadko image analysis from t0+2 - t0+9 is: Tstart Tend r(AB) 1sigma 1.928 1.930 18.46 0.17 2.929 2.950 19.18 0.12 3.941 3.974 19.86 0.21 4.955 4.964 20.20 0.23 5.953 5.973 >20.6 6.958 6.978 >20.6 7.955 7.976 >20.6 Observations are compatible with a power law decay (alpha=-2) or with a exponential decay with a half time of 1.25 days. The Zadko Telescope is operated by the University of Western Australia (UWA), and was made possible by a philanthropic donation by James Zadko, to UWA. Zadko Telescope receives support from the ARC Centre of Excellence "OzGrav" for gravitational wave follow-up and discovery. The facility is managed by D.Coward (Director-UWA), E. Howell (UWA), J. Moore (UWA), A. Burrel (UWA), A. Greensky, J. Kennewell with collaborators I. Andreoni and J. Cook (Swinburne) This observation report was done in partnership with the LIGO follow-up collaboration TZAC, which is supported by M. Boer, A. Klotz, R. Laugier, K. Noysena Title: The Radio Astronomy Group in 2016 Authors: Cook, J. Bibcode: 2017JBAA..127...73C Altcode: No abstract at ADS Title: Landing Site Assessment for Phase Two of eDSH-Enabled Lunar Missions Being Examined as an ISECG-GER Mission Scenario Authors: Ende, J. J.; Allender, E. J.; Almeida, N. V.; Cook, J.; Kamps, O.; Mazrouei, S.; Orgel, C.; Slezak, T. J.; Soini, A. J.; Kring, D. A. Bibcode: 2017LPI....48.1880E Altcode: Evaluation of five-year, five-landing site humans to the lunar surface campaign. Title: Desert Rats as a Space Camp Funded Activity Authors: Cook, J. Bibcode: 2017LPI....48.1041C Altcode: Desert Rats has not been funded for years; instead of asking NASA for funding, it is proposed to fund Desert Rats by making it an extension of a Space Camp. Title: Exploration of South Polar Region of the Moon: Tele-Operated Traverses Authors: Kamps, O. M.; Allender, E. J.; Almeida, N. V.; Cook, J.; Ende, J. J.; Mazrouei, S.; Orgel, C.; Slezak, T.; Soini, A. J.; Kring, D. A. Bibcode: 2017LPI....48.1909K Altcode: Comparison of efficient and science, tele-operated traverses between five human landing sites for exploration of the south pole of the Moon. Title: CERN@school: bringing CERN into the classroom Authors: Whyntie, T.; Cook, J.; Coupe, A.; Fickling, R. L.; Parker, B.; Shearer, N. Bibcode: 2016NPPP..273.1265W Altcode: CERN@school brings technology from CERN into the classroom to aid with the teaching of particle physics. It also aims to inspire the next generation of physicists and engineers by giving participants the opportunity to be part of a national collaboration of students, teachers and academics, analysing data obtained from detectors based on the ground and in space to make new, curiosity-driven discoveries at school. CERN@school is based around the Timepix hybrid silicon pixel detector developed by the Medipix 2 Collaboration, which features a 300 μm thick silicon sensor bump-bonded to a Timepix readout ASIC. This defines a 256-by-256 grid of pixels with a pitch of 55 μm, the data from which can be used to visualise ionising radiation in a very accessible way. Broadly speaking, CERN@school consists of a web portal that allows access to data collected by the Langton Ultimate Cosmic ray Intensity Detector (LUCID) experiment in space and the student-operated Timepix detectors on the ground; a number of Timepix detector kits for ground-based experiments, to be made available to schools for both teaching and research purposes; and educational resources for teachers to use with LUCID data and detector kits in the classroom. By providing access to cutting-edge research equipment, raw data from ground and space-based experiments, CERN@school hopes to provide the foundation for a programme that meets the many of the aims and objectives of CERN and the project's supporting academic and industrial partners. The work presented here provides an update on the status of the programme as supported by the UK Science and Technology Facilities Council (STFC) and the Royal Commission for the Exhibition of 1851. This includes recent results from work with the GridPP Collaboration on using grid resources with schools to run GEANT4 simulations of CERN@school experiments. Title: The Radio Astronomy Group in 2015 Authors: Cook, J. Bibcode: 2016JBAA..126...73C Altcode: No abstract at ADS Title: A Low Noise, High QE, Large Format CCD Camera System for the NASA MIGHTI Instrument Authors: Hancock, J. J.; Cardon, J.; Watson, M.; Cook, J.; Whiteley, M.; Beukers, J.; Englert, C. R.; Brown, C. M.; Harlander, J. Bibcode: 2015AGUFMSA51C2414H Altcode: The Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument is part of the NASA Ionspheric Connection Explorer (ICON) mission designed to uncover the mysteries of the extreme variability of the Earth's ionosphere. MIGHTI consists of two identical units positioned to observe the Earth's low latitude thermosphere from perpendicular viewing directions. The MIGHTI instrument is a spatial heterodyne spectrometer and requires a low noise, high QE, large format camera system to detect slight phase changes in the fringe patterns which reveal the neutral wind velocity. The MIGHTI camera system uses a single control electronics box to operate two identical CCD camera heads and communicate with the ICON payload electronics. The control electronics are carefully designed for a low noise implementation of CCD biases, clocking, and CCD output digitization. The camera heads consist of a 2k by 2K, back-illuminated, frame transfer CCD provided by e2v. The CCD's are both TEC cooled and have butcher-block filters mounted in close proximity of the active area. The CCDs are nominally operated in binned mode, the control electronics register settings provide flexibility for binning and gain control. An engineering model of the camera system has been assembled and tested. The EM camera system characterization meets all performance requirements. Performance highlights include a measured read noise of 5.7 electrons and dark current of 0.01 electronics/pixel/second. The camera system design and characterization results will be presented. Title: First extreme and far ultraviolet spectrum of a Comet Nucleus: Results from 67P/Churyumov-Gerasimenko Authors: Stern, S. A.; Feaga, L. M.; Schindhelm, R.; Steffl, A.; Parker, J. Wm.; Feldman, P. D.; Weaver, H. A.; A'Hearn, M. F.; Cook, J.; Bertaux, J. -L. Bibcode: 2015Icar..256..117S Altcode: We used the Alice spectrograph onboard the Rosetta comet orbiter spacecraft to observe the surface of Comet 67P/Churyumov-Gerasimenko in the extreme and far ultraviolet (EUV/FUV) from 700 to 2050 Å in mid-August 2014. These observations were before significant EUV/FUV coma signatures were observed by Alice. The resulting coadded spectrum has high signal to noise and reveals: (1) a very FUV-dark surface with (2) a blue spectral slope and (3) no evidence of significant H2O ice absorption in the FUV. We fit the measured reflectance spectrum with a model including 99.5% tholins, 0.5% H2O-ice, and a neutral darkening agent. Since we could not find any natural material with sufficiently low EUV/FUV reflectance, we interpret the low I/F as evidence of a fluffy, light-trapping surface. We interpret the blue spectral slope as consistent with a surface consisting primarily of tholins, though it may alternatively be the result of Rayleigh scattering by fine particles in the regolith. Title: The Radio Astronomy Group in 2014 Authors: Cook, J. Bibcode: 2015JBAA..125R.137C Altcode: No abstract at ADS Title: Design, Development, Implementation, and On-orbit Performance of the Dynamic Ionosphere CubeSat Experiment Mission Authors: Fish, C. S.; Swenson, C. M.; Crowley, G.; Barjatya, A.; Neilsen, T.; Gunther, J.; Azeem, I.; Pilinski, M.; Wilder, R.; Allen, D.; Anderson, M.; Bingham, B.; Bradford, K.; Burr, S.; Burt, R.; Byers, B.; Cook, J.; Davis, K.; Frazier, C.; Grover, S.; Hansen, G.; Jensen, S.; LeBaron, R.; Martineau, J.; Miller, J.; Nelsen, J.; Nelson, W.; Patterson, P.; Stromberg, E.; Tran, J.; Wassom, S.; Weston, C.; Whiteley, M.; Young, Q.; Petersen, J.; Schaire, S.; Davis, C. R.; Bokaie, M.; Fullmer, R.; Baktur, R.; Sojka, J.; Cousins, M. Bibcode: 2014SSRv..181...61F Altcode: 2014SSRv..tmp....2F Funded by the NSF CubeSat and NASA ELaNa programs, the Dynamic Ionosphere CubeSat Experiment (DICE) mission consists of two 1.5U CubeSats which were launched into an eccentric low Earth orbit on October 28, 2011. Each identical spacecraft carries two Langmuir probes to measure ionospheric in-situ plasma densities, electric field probes to measure in-situ DC and AC electric fields, and a science grade magnetometer to measure in-situ DC and AC magnetic fields. Given the tight integration of these multiple sensors with the CubeSat platforms, each of the DICE spacecraft is effectively a "sensor-sat" capable of comprehensive ionospheric diagnostics. The use of two identical sensor-sats at slightly different orbiting velocities in nearly identical orbits permits the de-convolution of spatial and temporal ambiguities in the observations of the ionosphere from a moving platform. In addition to demonstrating nanosat-based constellation science, the DICE mission is advancing a number of groundbreaking CubeSat technologies including miniaturized mechanisms and high-speed downlink communications. Title: The Radio Astronomy Group, 2013 Authors: Cook, J. Bibcode: 2014JBAA..124...66C Altcode: No abstract at ADS Title: The Radio Astronomy Group in 2012 Authors: Cook, J. Bibcode: 2013JBAA..123..133C Altcode: Solar activity detected during 2012 by the Radio Astronomy Group Title: Meeting contribution: SIDs, SFEs and CMEs in 2012 Authors: Cook, J. Bibcode: 2013JBAA..123..167C Altcode: No abstract at ADS Title: U.S. government export control reform initiative - what's going on? Authors: Cook, J.; Cook, K. Bibcode: 2013aero.confE..47C Altcode: While there is still more work to be done, taken together, these reforms will focus our resources on the threats that matter most, and help us work more effectively with our allies in the field. They'll bring transparency and coherence to a field of regulation which has long been lacking both. And by enhancing the competitiveness of our manufacturing and technology sectors, they'll help us not just increase exports and create jobs, but strengthen our national security as well.” - President Obama, Department of Commerce Annual Export Controls Update Conference, August 30, 2010. This paper will provide background information and discuss the need for export control reform. It will lay out the schedule for the Export Control Reform Initiative as well as provide an update on the current status of the ECR Initiative, including advances made in Phases I and II. It will provide insight into the proposed changes to the USML and the CCL and will discuss the proposed IT system modernization and the Export Enforcement Coordination Center (E2C2). Title: Modeling Insights into the Lunar Exosphere Authors: Hurley, D.; Feldman, P. D.; Retherford, K. D.; Cook, J.; Stern, S. A. Bibcode: 2012AGUFM.P42B..06H Altcode: In addition to Apollo data from the 1970s and ground-based observations, recent data from the Lyman Alpha Mapping Project (LAMP) onboard the Lunar Reconnaissance Orbiter (LRO) are revealing the structure and variability of the lunar exosphere. LAMP has detected helium in the lunar exosphere having many sources of variability. We use a Monte Carlo model to interpret variability in the observations of helium in the lunar exosphere from LAMP. Some of the variability stems from a time-varying source rate. Because the helium in the lunar exosphere predominately derives from the solar wind, we investigate the timescale of transport from release on the dayside to the nightside where it is observed. The model computes transport times for various assumptions about the energy distribution during the initial release and the effects of subsequent surface interactions on the ballistic transport. Owing to the changing geometry of the LRO orbit, spatial gradients also factor into the variability of the observations. We study the expected column density of helium as a function of latitude and longitude using surface temperatures measured by Diviner. The spatial distribution resulting from model runs is strongly influenced by the surface temperature and the assumed thermalization parameter. These dependencies can be used to extract information about the surface interactions. We compare model latitude and longitude dependences to LAMP and Apollo data. Finally, using upstream solar wind measurements and the position of LRO, we calculate the model time-varying helium exosphere of the Moon for comparison with LAMP data obtained in January, June, and July of 2012, including three passages of the Moon through Earth's magnetotail. Title: Lunar Atmospheric Helium Detections By the LAMP UV Spectrograph On the NASA Lunar Reconnaissance Orbiter Authors: Stern, S. Alan; Retherford, K.; Cook, J.; Tsang, C.; Feldman, P.; Pryor, W.; Gladstone, R. Bibcode: 2012DPS....4440109S Altcode: The LAMP far ultraviolet spectrograph aboard the NASA Lunar Reconnaissance Orbiter (LRO) was used in 2011 to search for the lightest noble gas, helium, in the tenuous lunar atmosphere. Based on that search, we report here the first detection of lunar atmospheric He by remote sensing, and point to future observations that can address questions about its source. We also report the discovery of lunar He atmospheric abundance variations detected by LAMP, including what appear to be several short-lived, extreme abundance increase events. If these are confirmed, the logical next question will be to determine whether they are of indigenous or exogenous origin. If they are of indigenous origin, they may offer a way to measure some kinds of lunar internal activity or seismicity from orbit. Title: The Radio Astronomy Group in 2011 Authors: Cook, J. Bibcode: 2012JBAA..122..145C Altcode: No abstract at ADS Title: The X-Shooter spectrum of (136199) Eris Authors: Alvarez-Candal, A.; Pinilla-Alonso, N.; Licandro, J.; Cook, J.; Mason, E.; Roush, T.; Cruikshank, D.; Gourgeot, F.; Dotto, E.; Perna, D. Bibcode: 2011epsc.conf..524A Altcode: 2011DPS....43..524A We observe Eris, one of the largest trans-Neptunian objects, in the 300 - 2480 nm range with X-Shooter, the first second-generation instrument for the ESOVery Large Telescope, and compare the newly obtained spectra with those available in the literature. The large spectra coverage and high resolving power (?/?? ' 5000) of X-Shooter allow us to study absorption features due to CH4 and search for other ices' absorptions. We measure the positions and depth of CH4 absorption features and compare them with those of reflectance of pure methane ice obtained from the optical constants of this ice at 30 K to study shifts in their positions. We do not directly detect absorption bands due to N2 or CO ices in the spectra. Nevertheless, the measured wavelength shifts of the CH4 absorption features points to a dilution of this ice in another one on the surface of Eris and the presence of pure CH4 spatially segregated. The comparison of the centers and shapes of these bands with previous works suggest that the surface is heterogeneous. Title: Analysis of High Resolution Spectra of Eris: Possible Evidence for Cold Phase CH4 Ice Authors: Cook, J.; Mastrapa, R. M.; Cruikshank, D. P.; Alvarez-Candal, A.; Pinilla-Alonso, N. Bibcode: 2011epsc.conf.1279C Altcode: 2011DPS....43.1279C We examined the spectrum of Eris by isolating the 1.67 and 1.72 μm CH4 bands and comparing these to Hapke models. These bands are chosen because (i) CH4(II) is more distinguished from CH4(I) at these wavelengths and (ii) the SNR of the observationswere higher than the bands longward of 1.8 μm. At the time of writing this abstract, the analysis was performed using optical constants for pure CH4 because of the lack of optical constants for CH4 diluted in N2 between 15 and 30 K.We assume the spectrum of Eris is a spectral blend of both CH4 phases. To model the spectrum, we used the CH4 optical constants from (11). CH4(II) ice is represented by their 20 K measurements, while optical constants for the CH4(I) ice is estimated from a linear interpolation between measurements at T > 30 K, or a second order extrapolation of the data at T > 30 to estimate the optical constants at 20.4 < T < 30 K. Each component is allowed to shift in wavelength. Title: The spectrum of (136199) Eris between 350 and 2350 nm: results with X-Shooter Authors: Alvarez-Candal, A.; Pinilla-Alonso, N.; Licandro, J.; Cook, J.; Mason, E.; Roush, T.; Cruikshank, D.; Gourgeot, F.; Dotto, E.; Perna, D. Bibcode: 2011A&A...532A.130A Altcode: 2011arXiv1107.1708A Context. X-Shooter is the first second-generation instrument for the ESO-Very Large Telescope. It is a spectrograph covering the entire 300-2480 nm spectral range at once with a high resolving power. These properties enticed us to observe the well-known trans-Neptunian object (136199) Eris during the science verification of the instrument. The target has numerous absorption features in the optical and near-infrared domain that have been observed by different authors, showing differences in these features' positions and strengths.
Aims: Besides testing the capabilities of X-Shooter to observe minor bodies, we attempt to constrain the existence of super-volatiles, e.g., CH4, CO and N2, and in particular we try to understand the physical-chemical state of the ices on Eris' surface.
Methods: We observed Eris in the 300 - 2480 nm range and compared the newly obtained spectra with those available in the literature. We identified several absorption features, measured their positions and depth, and compare them with those of the reflectance of pure methane ice obtained from the optical constants of this ice at 30 K to study shifts in these features' positions and find a possible explanation for their origin.
Results: We identify several absorption bands in the spectrum that are all consistent with the presence of CH4 ice. We do not identify bands related to N2 or CO. We measured the central wavelengths of the bands and compared to those measured in the spectrum of pure CH4 at 30 K finding variable spectral shifts.
Conclusions: Based on these wavelength shifts, we confirm the presence of a dilution of CH4 in other ice on the surface of Eris and the presence of pure CH4 that is spatially segregated. The comparison of the centers and shapes of these bands with previous works suggests that the surface is heterogeneous. The absence of the 2160 nm band of N2 can be explained if the surface temperature is below 35.6 K, the transition temperature between the alpha and beta phases of this ice. Our results, including the reanalysis of data published elsewhere, point to a heterogeneous surface on Eris.

Observations made during X-Shooter Science Verification, program 60.A-9400(A), PIs: Alvarez-Candal and Mason. Title: An introduction to solar radio astronomy Authors: Cook, J. Bibcode: 2011JBAA..121..241C Altcode: No abstract at ADS Title: The Radio Astronomy Group in 2010 Authors: Cook, J. Bibcode: 2011JBAA..121..133C Altcode: No abstract at ADS Title: Micrometeorite Annealing of Solar System Icy Objects Authors: Porter, Simon; Desch, S.; Cook, J. Bibcode: 2009DPS....41.6508P Altcode: Near-IR spectral observations appear to show that crystalline water ice is common in the outer solar system. This is unexpected, as amorphous solid water (ASW) is also stable beyond the orbit of Jupiter, and produced when crystalline ice is exposed to radiation. The annealing of surface ASW to crystalline ice through the impact heat of interplanetary micrometeorites may be sufficient to explain the observed crystalline spectra of many icy satellites. Through numerical modeling of both impact thermal diffusion and gravitational focusing, we have found that interplanetary dust particle impacts may provide a sufficient kinetic energy flux to effectively anneal ASW on geologically fast timescales. We estimated that this rate is sufficient to compete with ice amorphization by ultraviolet and ion irradiation for most of the saturnian and uranian satellites. This effect is strongly amplified by the proximity of the satellite to its planet, due to both gravitational focusing and the satellite's planetocentric velocity. Though these calculations were made for pure ice and assume spherical diffusion, we further show that icy-rocky mixtures and cylindrical diffusion both result in higher annealing rates. Impact annealing due to planetary dust (i.e. the E ring) was not effective. In addition, this model can be applied to explaining the crystallinity of Kuiper Belt object (KBO) surfaces. Though they have lower heliocentric velocities and no giant planet to gravitationally focus dust, the dust fluxes in the Kuiper Belt may be large enough to anneal ASW. Micrometeorite annealing could therefore explain that unexpectedly high crystallinity of objects not expected to have active surface cryovolcanism, like Haumea. If the method is effective on KBOs, it may in turn be used to as a probe of Kuiper Belt dust as function of distance from the Sun. Title: Solar EUV Spectral Irradiance Throughout The 3-Dimensional Heliosphere Authors: McMullin, D. R.; Auchere, F.; Cook, J. W.; Newmark, J. S.; Quemerais, E.; von Steiger, R.; Witte, M. Bibcode: 2008AGUFMSH13B1522M Altcode: When Ulysses moved from 30 to 80 degrees in solar latitude (July 2001), the Ulysses GAS instrument measured an apparent increase in the neutral He density. This is more naturally interpreted as a latitudinal dependence (decrease) of the loss rate due to solar photoionization rather than a true increase of the neutral He density. This concept has been tested through the development of a 3-Dimensional solar EUV model for the Heliosphere. The model concept has been presented earlier, and we are now presenting results and applications of the new model. Using daily SOHO EIT observations, over successive Carrington rotations, we have developed a three- dimensional model for solar EUV fluxes observed at any heliospheric position, projected to any heliospheric position. The combined effects of solar rotational and latitude-dependent flux variability are explicitly treated in this model. The flux model will be compared with other direct spectral irradiance observations in the ecliptic plane, such as those available from the TIMED SEE instrument as well as broadband measurements available from the SOHO/SEM irradiance time series. These comparisons will be used in part to validate the current results. We then use this flux to compute the photoionization rate of the in-flowing neutral Helium, and compare the modeled change with that observed along the spacecraft trajectory with the direct measurements from the out-of-ecliptic Ulysses GAS observations. The unique GAS comparisons will provide validation of the original hypothesis as to the latitudinal dependence (decrease) of the loss rate due to solar photoionization rather than an increase of the neutral He density. Title: Inverse Whitelight Reconstruction of STEREO-observed CMEs Authors: Antunes, A.; Cook, J. W.; Newmark, J. S.; Ontiveros, V.; Thernisien, A. Bibcode: 2008AGUSMSH21A..07A Altcode: With STEREO spacecraft separation now at greater than 40 degrees, we can examine 3D reconstructions using white light coronagraph data to constrain the observed CME underlying morphology and kinematics. We reconstruct the electron densities for the December 31, 2007 CME and associated streamer using individual pairs of STEREO observations from the COR 2 coronagraph, and then add a third viewpoint with LASCO coronagraph observations from SOHO. We also examine kinematics for the December 31 CME from successive reconstructions of the event during its development. Our tomographic technique uses the PIXON algorithm for our reconstructions. We overlay these results with forward reconstruction of a model flux rope and with geometric line-of-sight mass integrations. We also compare these results with other 2008 CMEs, and finally, illustrate how the community can use our publicly available reconstruction toolkit. Title: Theoretical modeling for the stereo mission Authors: Aschwanden, Markus J.; Burlaga, L. F.; Kaiser, M. L.; Ng, C. K.; Reames, D. V.; Reiner, M. J.; Gombosi, T. I.; Lugaz, N.; Manchester, W.; Roussev, I. I.; Zurbuchen, T. H.; Farrugia, C. J.; Galvin, A. B.; Lee, M. A.; Linker, J. A.; Mikić, Z.; Riley, P.; Alexander, D.; Sandman, A. W.; Cook, J. W.; Howard, R. A.; Odstrčil, D.; Pizzo, V. J.; Kóta, J.; Liewer, P. C.; Luhmann, J. G.; Inhester, B.; Schwenn, R. W.; Solanki, S. K.; Vasyliunas, V. M.; Wiegelmann, T.; Blush, L.; Bochsler, P.; Cairns, I. H.; Robinson, P. A.; Bothmer, V.; Kecskemety, K.; Llebaria, A.; Maksimovic, M.; Scholer, M.; Wimmer-Schweingruber, R. F. Bibcode: 2008SSRv..136..565A Altcode: 2006SSRv..tmp...75A We summarize the theory and modeling efforts for the STEREO mission, which will be used to interpret the data of both the remote-sensing (SECCHI, SWAVES) and in-situ instruments (IMPACT, PLASTIC). The modeling includes the coronal plasma, in both open and closed magnetic structures, and the solar wind and its expansion outwards from the Sun, which defines the heliosphere. Particular emphasis is given to modeling of dynamic phenomena associated with the initiation and propagation of coronal mass ejections (CMEs). The modeling of the CME initiation includes magnetic shearing, kink instability, filament eruption, and magnetic reconnection in the flaring lower corona. The modeling of CME propagation entails interplanetary shocks, interplanetary particle beams, solar energetic particles (SEPs), geoeffective connections, and space weather. This review describes mostly existing models of groups that have committed their work to the STEREO mission, but is by no means exhaustive or comprehensive regarding alternative theoretical approaches. Title: Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) Authors: Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.; Socker, D. G.; Plunkett, S. P.; Korendyke, C. M.; Cook, J. W.; Hurley, A.; Davila, J. M.; Thompson, W. T.; St Cyr, O. C.; Mentzell, E.; Mehalick, K.; Lemen, J. R.; Wuelser, J. P.; Duncan, D. W.; Tarbell, T. D.; Wolfson, C. J.; Moore, A.; Harrison, R. A.; Waltham, N. R.; Lang, J.; Davis, C. J.; Eyles, C. J.; Mapson-Menard, H.; Simnett, G. M.; Halain, J. P.; Defise, J. M.; Mazy, E.; Rochus, P.; Mercier, R.; Ravet, M. F.; Delmotte, F.; Auchere, F.; Delaboudiniere, J. P.; Bothmer, V.; Deutsch, W.; Wang, D.; Rich, N.; Cooper, S.; Stephens, V.; Maahs, G.; Baugh, R.; McMullin, D.; Carter, T. Bibcode: 2008SSRv..136...67H Altcode: 2008SSRv..tmp...64H The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) is a five telescope package, which has been developed for the Solar Terrestrial Relation Observatory (STEREO) mission by the Naval Research Laboratory (USA), the Lockheed Solar and Astrophysics Laboratory (USA), the Goddard Space Flight Center (USA), the University of Birmingham (UK), the Rutherford Appleton Laboratory (UK), the Max Planck Institute for Solar System Research (Germany), the Centre Spatiale de Leige (Belgium), the Institut d’Optique (France) and the Institut d’Astrophysique Spatiale (France). SECCHI comprises five telescopes, which together image the solar corona from the solar disk to beyond 1 AU. These telescopes are: an extreme ultraviolet imager (EUVI: 1 1.7 R⊙), two traditional Lyot coronagraphs (COR1: 1.5 4 R⊙ and COR2: 2.5 15 R⊙) and two new designs of heliospheric imagers (HI-1: 15 84 R⊙ and HI-2: 66 318 R⊙). All the instruments use 2048×2048 pixel CCD arrays in a backside-in mode. The EUVI backside surface has been specially processed for EUV sensitivity, while the others have an anti-reflection coating applied. A multi-tasking operating system, running on a PowerPC CPU, receives commands from the spacecraft, controls the instrument operations, acquires the images and compresses them for downlink through the main science channel (at compression factors typically up to 20×) and also through a low bandwidth channel to be used for space weather forecasting (at compression factors up to 200×). An image compression factor of about 10× enable the collection of images at the rate of about one every 2 3 minutes. Identical instruments, except for different sizes of occulters, are included on the STEREO-A and STEREO-B spacecraft. Title: Slow Monopole Signals in Water and Ice Detectors Authors: Cook, J.; Paul, T.; Reucroft, S.; Swain, J. Bibcode: 2008ICRC....4..825C Altcode: 2008ICRC...30d.825C We consider the possible use of water and ice detectors designed for other purposes as detectors for slow magnetic monopoles. The mechanism we assume to dominate is monopole catalyzed baryon decay which can very efficiently turn protons into electromagnetic energy. Estimates of sensitivity for existing detectors are given. Title: SCROD: An Update Authors: Cook, J.; Musienko, Y.; McCauley, T.; Paul, T.; Reucroft, S.; Swain, J. Bibcode: 2008ICRC....2..465C Altcode: 2008ICRC...30b.465C We give an update on the most recent design of the "School Cosmic Ray Outreach Detector'' (SCROD) using pixellated Geiger-mode avalanche photodiodes and scintillating tiles with wavelength shifting fibers as detectors. This technology offers very high levels of robustness at low cost. Voltages and currents are also so low as to reduce shock hazard to zero, and there are no fragile glass or vacuum-containing components. Plans are underway to make a very large-scale deployment of such detectors as part of a major outreach project. Title: The SECCHI experiment on STEREO Authors: Newmark, J. S.; Cook, J. W.; Moses, J. D. Bibcode: 2007SPIE.6689E..02N Altcode: 2007SPIE.6689E...2N The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) developed for the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of optical telescopes that will, for the first time, observe the entire inner heliosphere from the solar surface out to the vicinity of Earth from twin spacecraft. SECCHI was developed by an international consortium led by the Naval Research Laboratory (NRL). The primary objective of the STEREO mission is to understand the Coronal Mass Ejection (CME) phenomenon, discovered in 1971, and most recently extensively observed by the NASA/ESA Solar and Heliospheric Observatory (SOHO). The SECCHI telescope suite is returning unprecedented views of the Sun and inner heliosphere. The SECCHI instruments on each of the two STEREO spacecraft observe CMEs from their initiation, through the corona, and into interplanetary space beyond the Earth's orbit. We present an overview of the development and early operations of the SECCHI experiment. Title: NRL EUV Imager: The Solar EUV Atmospheric Research Of The Corona And Heliosphere (SEARCH) Experiment Authors: Newmark, J. S.; Doschek, G. A.; Brown, C. M.; Cook, J. W.; Kilmchuk, J. A.; Korendyke, C. M.; Moses, J. D.; Myers, S. H.; Seely, J. F. Bibcode: 2007ESASP.641E..74N Altcode: Achieving the Solar Orbiter primary science goals requires knowledge of the fine structure of the solar atmosphere from chromospheric to coronal temperatures, and the structural links between these different temperature regions. An EUV imager is an ideal instrument for providing this crucial information, and the Solar Orbiter mission gives a unique opportunity to investigate the fine structure of the chromosphere, transition region, and corona at unprecedented high spatial resolution. We present a concept from the US Naval Research Laboratory (NRL) for providing an Extreme Ultraviolet (EUV) Imager for the Solar Orbiter mission, the "Solar EUV Atmospheric Research of the Corona and Heliosphere" (SEARCH) experiment. Title: Recent Cluster wideband studies of auroral kilometric radiation Authors: Mutel, R.; Menietti, D.; Christopher, I.; Gurnett, D.; Cook, J.; Frey, H. Bibcode: 2006ESASP.598E..79M Altcode: 2006cds..sympE..79M No abstract at ADS Title: Comparison of the Sacramento Peak Fe XIV Index with a Model Index Computed from Differential Emission Measure Maps Authors: Cook, J. W.; Newmark, J. S.; Altrock, R. C. Bibcode: 2005ApJ...633..518C Altcode: We compare the Sacramento Peak Fe XIV 5303 Å green line index with a model index time series for the period of operations of the EUV Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO), covering the years 1996-2002, from cycle minimum past the peak of the current activity cycle 23. We compute a differential emission measure (DEM) map for each day using images from the four channels of EIT at 171, 195, 284, and 304 Å. From the daily DEM map we then calculate a daily synthetic Fe XIV 5303 Å intensity image. The Sacramento Peak index is an average intensity, measured using a circular aperture 1.1 arcmin in diameter, sampling the off-limb corona in 3° steps around disk center. It is taken at several different heights beyond the daily white light limb. We modeled the daily index values, for the aperture center at 1.15 and 1.25 Rsolar from disk center, as the weighted average intensity within an annulus covering 1.11-1.19 and 1.21-1.29 Rsolar superposed on the daily synthetic intensity image. We compare the observed index with our model results and find a high correlation of the short-term values but a long-term systematic difference in the absolute values. We examine the accuracy of the respective calibrations and argue that the model results, based on the calibration of the EIT images used to produce the daily DEM maps, are more plausible in absolute value. Title: A Model for Solar EUV Flux Helium Photoionization Throughout the 3-Dimensional Heliosphere Authors: Auchère, F.; McMullin, D. R.; Cook, J. W.; Newmark, J. S.; von Steiger, R.; Witte, M. Bibcode: 2005ESASP.592..327A Altcode: 2005soho...16E..49A; 2005ESASP.592E..49A No abstract at ADS Title: The Heliospheric He II 30.4 nm Solar Flux During Cycle 23 Authors: Auchère, F.; Cook, J. W.; Newmark, J. S.; McMullin, D. R.; von Steiger, R.; Witte, M. Bibcode: 2005ApJ...625.1036A Altcode: Because of the orbit characteristics of the vast majority of spacecraft, the solar flux has predominantly been measured at Earth or at least in the plane of the ecliptic. Therefore, the existing data do not directly demonstrate the fact that the latitudinal distribution of the extreme-ultraviolet (EUV) solar flux is largely anisotropic. Indeed, in the EUV the nonuniform distribution of very contrasted bright features (i.e., active regions) and dark features (i.e., coronal holes) at the surface of the Sun produces both the obvious rotational (or longitudinal) modulation of the flux and also a strong latitudinal anisotropy. Although largely ignored up to now, the latitudinal anisotropy affects the physical conditions in the corona and heliosphere and should therefore be taken into account in several solar and heliospheric physics applications. We describe in this paper a technique for computing the He II 30.4 nm flux at an arbitrary position in the heliosphere from Solar and Heliospheric Observatory (SOHO) EUV Imaging Telescope (EIT) images. This procedure was used to produce daily all-sky maps of the 30.4 nm flux from 1996 January to 2003 August, covering the first 8 yr of solar cycle 23. As could be expected from the examination of the EIT images, the 30.4 nm flux was found to be strongly anisotropic. The anisotropy Ipol/Ieq between the fluxes computed for viewpoints located above the solar poles and within the solar equatorial plane ranges from 0.9 at solar minimum to 0.6 at solar maximum. A 20% difference was also discovered between the north and south polar fluxes. The generalization of this technique to other lines of the EUV and far-ultraviolet (FUV) spectrum is discussed. Title: Morphological Classes and Stellar Populations of Galaxies in Introductory Astronomy Labs at Arizona State University Authors: Will, L. M.; Cook, J.; Scowen, P. Bibcode: 2005AAS...206.0208W Altcode: 2005BAAS...37..431W At Arizona State University, introductory astronomy lab students made observations of several galaxies visible in the spring sky. The students used the Hubble classification system introduced in the lab to assign morphological types to these galaxies. From creating color images and using their knowledge of stellar populations from previous lab exercises, the students were able to draw conclusions about the relative ages of galaxies and likelihood of ongoing star formation, This lab exercise involved remote observing with ASU's Braeside Observatory, located in Flagstaff, AZ. This poster will outline the laboratory exercise and student responses to this new addition to our astronomy lab curriculum. Title: Forward Modeling of CMEs Using LASCO Data and for the STEREO Mission Authors: Thernisien, A. F.; Howard, R. A.; Cook, J. W. Bibcode: 2005AGUSMSH52A..05T Altcode: The future STEREO mission, due to launch in early 2006, will have two twin satellites that will observe the Sun and its corona from two different points of view. The main goal of the mission is to understand how the CMEs are initiated and how they evolve during time. Using the two points of view will permit a reconstruction of the electron density and morphology of coronal structures such as CMEs. Two approaches are possible to reach that goal: an inversion technique, assuming no or little a priori assumptions of the structure, and a forward modeling technique, for which a morphology and location of the studied structure is assumed. In this poster we present a forward modeling method used to determined the electron density of different CMEs from SOHO-LASCO data. We used the graduated cylindrical shell (GCS) model, an empirical simulation of a flux-rope CME. We used time sequences and assumption of self similarity to have many views of the same CME for a best fit. We used also minimization techniques to find the best fit of the different model parameters. Title: Solar EUV and UV spectral irradiances and solar indices Authors: Floyd, Linton; Newmark, Jeff; Cook, John; Herring, Lynn; McMullin, Don Bibcode: 2005JASTP..67....3F Altcode: 2005JATP...67....3F Several experiments have measured solar EUV/UV flux in the last 10 15 years including SUSIM UARS, SOHO CELIAS SEM, and SOHO EIT and have generated multi-year spectral irradiance time series. Empirical models of these important sources of radiant energy are often based on solar activity proxies, most often, the solar 10.7 cm radio flux (F10.7). The short- and long-term correspondence of four solar activity index time series International Sunspot Number, the He 1083 Equivalent Width, F10.7, and the Mg II core-to-wing ratio are analyzed. All of these show well-correlated long-term behavior with F10.7 and Mg II showing the greatest long-term agreement among all of the index pairs. However, during the recent maximum period of solar cycle 23, both the ISN and He 1083 have diverged significantly from the others. Recent UV and EUV measurements are compared with Mg II and F10.7 to assess their value as solar activity proxies. In every case, Mg II was found to correlate more strongly than F10.7 with the UV and EUV time series which correspond to a range of solar atmospheric temperatures of 4000K 2 MK. This correspondence indicates that the mechanisms underlying irradiances changes from upper photospheric chromospheric, transition region, and lower coronal solar atmospheric layers are closely linked. Title: SCROD: A new approach to large school based cosmic ray experiments Authors: Swain, J.; Cook, J.; Gouchtchine, E.; Musienko, Y.; Paul, T.; Reucroft, S. Bibcode: 2005ICRC....9..323S Altcode: 2005ICRC...29i.323S No abstract at ADS Title: Model of the all-sky He II 30.4 nm solar flux Authors: Auchère, F.; Cook, J. W.; Newmark, J. S.; McMullin, D. R.; von Steiger, R.; Witte, M. Bibcode: 2005AdSpR..35..388A Altcode: Because of the orbit characteristics of the vast majority of spacecraft, the solar flux has been generally measured at Earth or in the plane of the ecliptic. So far, most published studies did not consider the fact that the extreme ultraviolet (EUV) solar flux is largely anisotropic. Indeed, in the EUV, the distribution of very contrasted bright and dark features at the surface of the Sun produces both the obvious rotational (longitudinal) modulation of the flux, but also a strong latitudinal anisotropy. Although largely ignored up to now, the latitudinal anisotropy affects the physical conditions in the corona and heliosphere. We describe an empirical model of the all-sky He II 30.4 nm flux based on EIT/ SOHO data. The 30.4 nm flux was found to be strongly anisotropic. The anisotropy Ipol/ Ieq between the fluxes computed for viewpoints located above the solar poles and within the solar equatorial plane ranges from 0.9 at solar minimum to 0.6 at solar maximum. A 20% asymmetry was also discovered between the north and south polar fluxes. Title: A Model For EUV Flux Throughout The 3-Dimensional Heliosphere Authors: McMullin, D. R.; Auchere, F.; Cook, J.; Newmark, J. S.; Quemerais, E.; von Steiger, R.; Witte, M. Bibcode: 2004AGUFMSH21B0423M Altcode: After July 2001, when Ulysses moved from 30 to 80 degrees in solar latitude, the Ulysses GAS instrument measured an apparent increase in the neutral He density. This is more naturally interpreted as a latitudinal dependence (decrease) of the loss rate due to solar photoionization rather than a true increase of the neutral He density. We have developed a three-dimensional model for solar EUV fluxes observed at any heliospheric position, using daily SOHO EIT observations, over successive Carrington rotations, projected to any heliospheric position. The combined effects of solar rotational and latitude-dependent flux variability are explicitly treated in this model. The flux model has been directly compared with other direct irradiance observations in the ecliptic plane with the SOHO/SEM irradiance time series for validation. We then use this flux to compute the photoionization rate of the in-flowing neutral He, and compare the modeled change with time along the spacecraft trajectory with the direct measurements from the out -of -ecliptic Ulysses GAS observations. The 3-D model developed will be directly applicable to STEREO EUV images from the SECCHI instrument suite. As the two spacecraft separate, the amount of the solar surface observed will increase through the mission, providing more accurate solar inputs. Title: Comparison of Tomographic and Forward Modeling 3D Reconstructions of a Coronal Streamer Authors: Newmark, J. S.; Cook, J.; Reiser, P.; Thernisien, A. Bibcode: 2004AGUFMSH21B0421N Altcode: We compare 3D reconstructions of a coronal streamer using two different techniques. Thernisien employs images from the LASCO coronagraph on board SOHO and determines the optimal parameter values of a general slab model (with folds) for electron density yielding a synthetic white light image that best matches the starting LASCO data (Thernisien et al. 2004, B.A.A.S., 36, 797). This forward modeling approach forces the solution to be of a pre-determined functional form. We compare this reconstruction with a true tomographic reconstruction using input images from multiple viewpoints, with no predetermined constraint on the geometry of the electron density distribution found. As an initial test of the tomographic reconstruction, we start with input synthetic coronagraph data rendered from the Thernisien model electron density reconstruction, and first compare the tomographic reconstruction to this known starting distribution. We next use true LASCO data from different days (rotational tomography) for a tomographic reconstruction, and compare the reconstructed electron density distribution and its rendered synthetic coronagraph data with the Thernisien electron densities and rendered coronagraph data. In general, with real data the tomographic reconstruction produces synthetic coronagraph images rendered from its electron density determination that are more similar to the input LASCO data, while the Thernisien electron density determination is more tightly structured, from its prior constraints, than the tomographic reconstruction from a very limited number of viewpoints. The two techniques are complementary, and both will provide useful reconstruction tools for use in the upcoming STEREO mission, due for launch in early 2006. JWC and JSN are supported on this work by NASA under W10135, and by the Office of Naval Research. Title: Solar UV Irradiance Measurements from SUSIM UARS Authors: Floyd, L. E.; Cook, J. W.; Herring, L. C. Bibcode: 2004AGUFMSH53B0309F Altcode: The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) aboard the Upper Atmosphere Research Satellite (UARS) has measured the solar UV irradiance since October 1991. This 13 year time period includes a secondary maximum of solar cycle 22, the ensuing solar minimum, the maximum of solar cycle 23, and its declining phase. SUSIM maintains the calibration of its changing responsivity through a combination of measurements of four stable onboard deuterium calibration lamps and measurements of infrequently exposed reference channels. The wavelength-dependent UV irradiance time series exhibit two dominant periodicities, that of solar rotation (27~days) and solar cycle (11~years). The solar cycle variation of the UV irradiance was similar for solar cycles~22 and 23: about 55% at Ly-α , about 7% at 205~nm, and less than 1% above 300~nm. The SUSIM measurements are compared with other coincident measurements including those of SOLSTICE over a similar time period and with the Mg~II core-to-wing ratio index. Prospects and requirements for continued and possibly improved monitoring of the solar UV irradiance are discussed. Title: The center-to-limb behavior of solar active regions at ultraviolet wavelengths Authors: Crane, P. C.; Floyd, L. E.; Cook, J. W.; Herring, L. C.; Avrett, E. H.; Prinz, D. K. Bibcode: 2004A&A...419..735C Altcode: The time series of solar ultraviolet irradiances measured by the Solar Ultraviolet Spectral Irradiance Monitor on the Upper Atmosphere Research Satellite have been analyzed to describe the center-to-limb behavior of the excess surface brightness of solar active regions over the wavelength range 142-265 nm. Comparison of these results with the analysis by Worden, Woods, and Bowman (2001, ApJ, 560, 1020) of the time series produced by the Solar-Stellar Irradiance Comparison Experiment on the same spacecraft over the wavelength range 120-170 nm shows excellent agreement. For 170-265 nm, we present new results on the center-to-limb behavior of the surface brightness of solar active regions. Comparisons with previous results for the quiet disk show roughly similar behaviors at wavelengths below 168 nm and above 210 nm, where both exhibit weak limb brightening and darkening, respectively. At intermediate wavelengths, 168-210 nm, active regions exhibit much stronger limb darkening than does the quiet disk. Our Fourier analysis and the multi-component modeling of Worden et al. (2001, ApJ, 560, 1020) are found to be complementary and could be productively combined in future work. We also compare our results with a similar analysis based upon the semi-empirical model atmospheres of Fontenla et al. (1999, ApJ, 518, 480), further improved by Avrett. We compare the measurement- and model-based analyses and suggest the direction of improvements needed in the model atmospheres. Title: The Secchi Experiment on the Stereo Mission Authors: Howard, R.; Moses, D.; Socker, D.; Cook, J.; Davila, J.; Lemen, J.; Harrison, R.; Eyles, C.; Waltham, N.; Defise, J. -M. Bibcode: 2004cosp...35.3893H Altcode: 2004cosp.meet.3893H The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of remote sensing instruments consisting of two white light coronagraphs, an extreme ultraviolet (EUV) imager, and a heliospheric imager. SECCHI will observe coronal mass ejections (CMEs) from their birth at the sun, through the corona and into the heliosphere. A complete instrument suite is being carried on each of the two STEREO spacecraft, which will provide the first sampling of a CME from two vantage points. The spacecraft will orbit the Sun, one ahead of the Earth and the other behind, separating from Earth at about 22 degrees per year. The varying separation means that we will have different observational capabilities as the spacecraft separate and therefore differing science goals. The primary science objectives all are focused on understanding the physics of the CME process - their initiation, 3D morphology, propagation, interaction with the interplanetary medium and space weather effects. By observing the CME from multiple viewpoints with UV and coronagraphic telescopes and by combining these observations with radio and in-situ observations from the other instruments on STEREO as well as from other satellites and ground based observatories operating at the same time, answers to some of the outstanding questions will be obtained. Title: Model for 3-D Heliospheric EUV Irradiance and Photoionization Authors: Auchère, F.; McMullin, D.; Cook, J.; Newmark, J.; Vonsteiger, R.; Witte, M.; Quémerais, E. Bibcode: 2004cosp...35.2558A Altcode: 2004cosp.meet.2558A For 8 years now, the EIT instrument on board SOHO continuously monitored the solar activity in four passbands of the EUV spectrum. With the SOHO mission extended, it is likely that the final EIT data set will cover one complete solar cycle. This exceptional data set offers an unprecedented opportunity to investigate the long-term variations of the solar EUV irradiance. Furthermore, with the spatial resolution of the EIT/SOHO instrument, the data can also be used to study variations of the solar irradiance with heliocentric latitude. It is indeed clear that the wide intensity range of the various emitting regions (polar coronal holes, equatorial active regions, etc.) produces a latitude-dependant irradiance. To date, due to the small number of off-ecliptic measurements, very few attempts have been made to investigate these variations. We present here an empirical model of the EUV solar flux at any point in the heliosphere derived from EIT/SOHO data. At 30.4 nm, the anisotropy I_⊥ / I_∥ between the irradiance above (⊥) and within (∥) the ecliptic plane is found to range from about 0.8 at solar minimum to about 0.6 at solar maximum. Our anisotropic EUV fluxes are used to improve the present estimates of the photoionization rate of in-flowing neutral helium. These new rates are compared to the relative changes of neutral helium density measured by the GAS/Ulysses instrument. Title: Solar UV and EUV Irradiance and Solar Indices Authors: Floyd, L.; Newmark, J.; Herring, L.; Cook, J.; McMullin, D. Bibcode: 2003AGUFMSH12A1162F Altcode: Studies of the solar UV (120--290~nm) spectral irradiance have shown that its variation correlates well with that of the core-to-wing ratio of the Mg~II compound absorption feature near 280~nm. The two chromospheric emission lines in the feature's core cause nearly all of the Mg~II index variation. The Mg~II index has also been shown to correlate with solar He~II emerging from the transition region. Although earlier studies appeared to show that an accurate representation of the solar Ly-α irradiance required the separation of the long- and short-term components of the Mg~II index, recently recalibrated measurements show that Ly-α also has a linear relationship with Mg~II. We analyze the solar spectral irradiance derived from SOHO EIT images roughly corresponding to coronal line emissions of Fe~IX/X, Fe~XII, and Fe~XV and find that the Mg~II index represents their variation more effectively than the more commonly used F10.7~cm flux. The long-term behavior of F10.7, Mg~II, and sunspot number are compared showing a strong divergence of the latter during the latter stages of the solar cycle~23 maximum. Title: Obituary: Dianne K. Prinz, 1938-2002 Authors: Cook, John William; Howard, Russell Alfred Bibcode: 2003BAAS...35.1469C Altcode: Dr. Dianne Kasnic Prinz died 12 October 2002 at the Hospice of Northern Virginia after a long struggle with lymphatic cancer. She worked for over 29 years until retirement at the Naval Research Laboratory in Washington, DC on sounding rocket, space shuttle, and satellite experiments to observe the Sun at ultraviolet wavelengths from space.

Dianne Prinz was born 29 September 1938. She received her BS degree from the University of Pittsburgh in 1960, and a PhD in Physics from Johns Hopkins University in 1967, where she was a University Fellow 1960--1964 and a Gilman Fellow 1960--1963. She was a Research Associate in the Physics Department of the University of Maryland 1967--1971 and, from 1971 until her retirement in February 2001, she was a Research Physicist at the Naval Research Laboratory (NRL). At the time of her retirement she was Head of the Solar Radiation Section, Solar Physics Branch, Space Science Division of the Naval Research Laboratory and was supervising the work of a team of scientists that was operating the SUSIM (Solar Ultraviolet Irradiance Monitor) experiment on the UARS (Upper Atmosphere Research Satellite) spacecraft as well as reducing and analyzing the observations.

Dianne was a member of the Washington Academy of Science (elected 1976 and Fellow 1987), served as Vice President of the National Capital Section of the Optical Society of America (1976), and received the Navy Award of Merit for Group Achievement (1985), the NASA Public Service Group Achievement Award (1987), and the Navy Meritorious Civilian Service Award (2001). Her professional memberships included the American Astronomical Society and its Solar Physics Division, the American Geophysical Union, and Sigma Xi. She had over 60 publications in her scientific bibliography.

Early in her career at NRL, Dianne developed a Lyman alpha spectroheliograph sounding rocket payload. Launching at White Sands Missile Range in 1972, she obtained high spatial resolution (for that day) full disk solar images. Her published analysis was pioneering for the study of the Lyman alpha irradiance and established the range of brightness of solar active regions relative to the quiet disk.

Dianne also had a keen interest in understanding how the upper atmosphere responds to changing solar conditions, a field of research now called ``space weather." Early in her career she collaborated with NRL scientists Robert Meier and Phillip Mange on the analysis of some of the first satellite remote sensing observations of the atmosphere and ionosphere. That work laid the foundation for many future NASA and DoD space weather programs, and throughout the years she continued to participate in the design of atmospheric remote sensing instruments that are flying in space today.

In 1978 Dianne was selected by NASA to train as a Payload Specialist astronaut to operate the solar instruments that were to fly on the Spacelab 2 mission aboard the Space Shuttle. From a group of four in training (the others were Drs. J.D.-F. Bartoe, Loren Acton, and George Simon), Bartoe and Acton were finally selected and flew on the Spacelab 2 mission in 1985, when Dianne served as mission communicator with the Payload Specialists. She and Simon were due to fly on a planned follow-up second flight but the aftermath of the explosion of the Challenger Space Shuttle shortly afterward led to cancellation and the end of this phase of her career. In addition to the scientific aspects of her work, she made a substantial effort to communicate her enthusiasm to the public. After the Spacelab 2 mission she often gave presentations to adult and student audiences on her experiences, sometimes bringing along her flight suit. She received letters from all over the world from correspondents who had read of her role.

Dianne was a member of the team at NRL that developed the requirements for a new instrument to accurately monitor, over many years, the solar ultraviolet irradiance, which was known to vary considerably and is a crucial input to many processes in the Earth's upper atmosphere. It was critical to overcome the challenge of maintaining the absolute calibration of an ultraviolet spectrometer. The new instrument, called the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM), was flown first on an early Space Shuttle flight (STS-3) and next on the NASA Spacelab 2 mission, for which she had trained as an astronaut payload specialist. The SUSIM design was then revised for a long-term flight aboard the Upper Atmosphere Research Satellite (UARS). After the launch in 1991 of the UARS SUSIM, she led the NRL team that ran the UARS SUSIM flight operations and developed the data analysis software. After the death of Guenter Brueckner, she became the Principal Investigator of UARS SUSIM and continued the operation, analysis, and publication of these critical scientific observations. To determine the SUSIM absolute calibration, careful studies were performed to separate the degradation of the instrument response from the true solar variability. Extensive work was necessary to model the degradation of the instrumental sensitivity with time, the stray light correction, the field-of-view correction, and the wavelength scale. Dianne managed these tasks and produced a long term, well-calibrated history of solar ultraviolet irradiances over the full activity levels of a solar cycle.

Dianne grew up on a farm in southwestern Pennsylvania, the daughter of Joseph J. Kasnic, a steel worker and part-time farmer, and Anna M. Kosyrich Kasnic, a homemaker, part-time teacher and accomplished artist and musician. Diane will be remembered for her deep love of animals, whether her beloved horse Chesterfield or stray or hungry cats in her neighborhood. Her marriage to Dr. Gary Prinz ended in divorce. She is survived by her sister and brother. Diane had an early interest in science and, throughout her career, worked as an experimental physicist and designer of optical instrumentation. She was a pioneer in her interests in space science, and usually overcame the obstacles she encountered in her field and at a time when she was often the first woman in authority encountered by male co-workers. She had a no-nonsense attitude in her work relations, but inspired the friendship of colleagues through her genuine good will, competence, and utter lack of pretension. Title: Investigations on the behaviour of Re on the site of Maqarin (Jordan) Authors: Trotignon, L.; Khoury, H.; Bienvenu, P.; Cook, J.; Mercier, F.; Trocellier, P.; Provitina, L. Raimbault O.; Arnal, N.; Adam, F. Bibcode: 2003GeCAS..67R.492T Altcode: No abstract at ADS Title: SUSIM'S 11-year observational record of the solar UV irradiance Authors: Floyd, L. E.; Cook, J. W.; Herring, L. C.; Crane, P. C. Bibcode: 2003AdSpR..31.2111F Altcode: The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM), a wavelength-scanning, dual-dispersion, dual-spectrometer instrument aboard the Upper Atmosphere Research Satellite (UARS), has measured the solar ultraviolet (UV) spectral irradiance (115-410 nm) since October 1991. This 11-year period, the duration of a solar activity cycle, extends from a late secondary maximum of solar cycle 22 through the intervening solar minimum and the maximum of solar cycle 23. Accordingly, SUSIM observed nearly the entire maximum-to-minimum variation of the solar UV irradiance of both solar cycles. The UV irradiance variations during the two solar cycles are compared. Apart from solar rotation effects and to within experimental accuracy, they show similar variation in the UV spectral irradiance. Solar cycle amplitudes calculated after removing solar rotation effects were ∼50% for the strong O I, C II, and Si IV emission features below 145 run, ∼8-18% between the A1 edge and 145 nm, respectively, and ∼4% between the Al edge and 263 nm. The amplitude of the solar cycle periodicity was not detected above ∼300 nm. Title: 3D Electron Density Reconstruction from the SECCHI White Light Coronagraphs Onboard Stereo Authors: Newmark, J. S.; Cook, J. W.; Reiser, P. A.; Yahil, A. Bibcode: 2003SPD....34.0202N Altcode: 2003BAAS...35..807N The twin STEREO spacecraft will carry onboard the SECCHI (Sun-Earth Connection Coronal and Heliospheric Investigation) experiment, consisting of an EUVI disk imager and three white light coronagraphs on each spacecraft. At NRL we are investigating the tomographic electron density reconstructions, and their limitations, that are achievable from just two viewpoints using the coronagraph observations. We discuss our reconstruction technique and show results from our current work. We started with geometrically simple constant density objects (cylinders, half-shells), and have proceeded on to several CME numerical models we have obtained from cooperating colleagues. We render from the starting known electron density distribution a perfect white light image, in radial and tangential polarizations, typically from two viewpoints in the elliptic plane, and then add noise. Using these input synthetic observations, we employ our PIXON reconstruction technique to produce a best (using fewest PIXON elements) electron density reconstruction that reproduces the input images. We discuss the agreement of the PIXON reconstructions with the known starting model electron density distributions which produced the input images. We are particularly interested in the limitations present when only two viewpoints are available. The reconstructions are significantly improved with the addition of a third viewpoint to the reconstruction, such as could be provided during the STEREO mission by an operating LASCO coronagraph on the SOHO spacecraft. Information on our project can be found from the web site http://stereo.nrl.navy.mil. This work is supported by NASA under S-13631-Y, and by the Office of Naval Research. The SECCHI experiment is an international collaboration led by the Naval Research Laboratory. Title: Solar EUV Variability as Measured by SOHO EIT and Future Application to SDO SHARPP Authors: Newmark, J.; Cook, J.; McMullin, D. Bibcode: 2003EAEJA....13798N Altcode: The SOHO EIT instrument obtains full disk images of the Sun through four channels; Fe IX,X (17.1nm), Fe XII (19.5nm), Fe XV (28.4nm), and He II (30.4nm). We construct a model differential emission measure (DEM) map, using the EIT images from the four channels, which accurately covers the temperature range 80,000 - 2.2 MK. Using our DEM modeling tool we calculate full disk EUV irradiances over the SOHO mission lifetime. The accuracy of our model is demonstrated with a long term comparison to the SOHO SEM instrument full disk irradiances. We provide a public database (SOHO EIT website) of daily, full disk, full resolution DEM maps from the SOHO EIT data as well as the software to create these maps. Software tools are made available in order to extract the irradiance for any EUV line, or defined passband, or calibrated spectra (using the CHIANTI atomic physics package) for full disk, or smaller regional average, over the entire field of view. The solar EUV variability is an important driver to geospace. Model irradiances from the DEM tools we have developed can be directly applied to thermospheric and ionospheric models, and as input into empirical models such as SOLAR2000 (Tobiska 2000), or used as an effective activity index for such modeling. As part of the public database, we provide a daily EUV irradiance spectrum (covering from 17-35 nm, 1 nm bins) covering the SOHO mission. Lastly, we have begun preliminary work in applying our DEM technique to the upcoming SDO SHARPP instrument. The increased temperature (emission line) coverage for this instrument, especially for the transition region, greatly enhances the fidelity of our models. Title: Measurements of Three-dimensional Coronal Magnetic Fields from Coordinated Extreme-Ultraviolet and Radio Observations of a Solar Active Region Sunspot Authors: Brosius, Jeffrey W.; Landi, Enrico; Cook, John W.; Newmark, Jeffrey S.; Gopalswamy, N.; Lara, Alejandro Bibcode: 2002ApJ...574..453B Altcode: We observed NOAA Active Region 8108 around 1940 UT on 1997 November 18 with the Very Large Array and with three instruments aboard the NASA/ESA Solar and Heliospheric Observatory satellite, including the Coronal Diagnostic Spectrometer, the EUV Imaging Telescope, and the Michelson Doppler Imager. We used the right-hand and left-hand circularly polarized components of the radio observing frequencies, along with the coordinated EUV observations, to derive the three-dimensional coronal magnetic field above the region's sunspot and its immediate surroundings. This was done by placing the largest possible harmonic (which corresponds to the smallest possible magnetic field strength) for each component of each radio frequency into appropriate atmospheric temperature intervals such that the calculated radio brightness temperatures at each spatial location match the corresponding observed values. The temperature dependence of the derived coronal magnetic field, B(x,y,T), is insensitive to uncertainties on the observed parameters and yields field strengths in excess of 580 G at 2×106 K and in excess of 1500 G at 1×106 K. The height dependence of the derived coronal magnetic field, B(x,y,h), varies significantly with our choice of magnetic scale height LB. Based on LB=3.8×109 cm derived from the relative displacements of the observed radio centroids, we find magnetic field strengths in excess of 1500 G at heights of 15,000 km and as great as 1000 G at 25,000 km. By observing a given target region on several successive days, we would obtain observations at a variety of projection angles, thus enabling a better determination of LB and, ultimately, B(x,y,h). We compare coronal magnetic fields derived from our method with those derived from a potential extrapolation and find that the magnitudes of the potential field strengths are factors of 2 or more smaller than those derived from our method. This indicates that the sunspot field is not potential and that currents must be present in the corona. Alfvén speeds between 25,000 and 57,000 km s-1 are derived for the 1×106 K plasma at the centroids of the radio observing frequencies. Filling factors between 0.003 and 0.1 are derived for the 1×106 K plasma at the centroids of the radio observing frequencies. Title: New Measurements of 3-D Sunspot Coronal Magnetic Fields From Coordinated SOHO EUV and VLA Radio Observations Authors: Brosius, J. W.; White, S. M.; Landi, E.; Cook, J. W.; Newmark, J. S.; Gopalswamy, N.; Lara, A. Bibcode: 2002AAS...200.0307B Altcode: 2002BAAS...34..642B Three-dimensional sunspot coronal magnetograms were derived from coordinated extreme-ultraviolet (EUV) and radio observations of NOAA regions 8108 (N21E18 on 1997 November 18) and 8539 (N20W12 on 1999 May 13). The EUV spectra and images, obtained with the Coronal Diagnostic Spectrometer (CDS) and the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO) satellite, were used to derive the differential emission measure (DEM) and the plasma electron density for each spatial pixel (along each line of sight) within both regions. These were subsequently used to calculate maps of the expected thermal bremsstrahlung brightness temperature at the Very Large Array (VLA) radio observing frequencies of 1.4, 4.9, 8.4, and 15 GHz. The thermal bremsstrahlung maps reproduce neither the structure nor the intensity of the observed maps, and indicate that thermal gyroemission must dominate the observed radio emission. The radio observations were used to constrain the magnetic scale height and the gross temperature structure of the atmosphere. These, along with the DEM, electron density, and observed radio brightness temperature maps, were used to derive the temperature distribution of the coronal magnetic field strength B(T) that reproduced simultaneously the observed right-hand and left-hand circularly polarized emission at the radio observing frequencies for each spatial pixel in the images. Magnetic field strengths corresponding to 3rd harmonic gyroemission at 4.9 GHz (580 Gauss) are found in coronal plasmas at temperatures as high as 3.2 MK, while magnetic field strengths corresponding to 3rd harmonic gyroemission at 15 GHz (1800 Gauss) are found in coronal plasmas at temperatures as high as 1.6 MK. B(T) was ultimately converted to B(h) and compared with extrapolations from photospheric magnetograms. Title: Sun earth connection coronal and heliospheric investigation (SECCHI) Authors: Howard, R. A.; Moses, J. D.; Socker, D. G.; Dere, K. P.; Cook, J. W.; Secchi Consortium Bibcode: 2002AdSpR..29.2017H Altcode: The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory ( STEREO) mission is a suite of remote sensing instruments consisting of an extreme ultraviolet imager, two white light coronagraphs, and a heliospheric imager. Two spacecraft with identical instrumentation will obtain simultaneous observations from viewpoints of increasing separation in the ecliptic plane. In support of the STEREO mission objectives, SECCHI will observe coronal mass ejections from their birth at the Sun, through the outer corona, to their impact at Earth. The SECCHI program includes a coordinated effort to develope magneto-hydrodynamic models and visualization tools to interpret the images that will be obtained from the two spacecraft viewpoints. The resulting three-dimensional analysis of CMEs will help to resolve some of the fundamental outstanding questions in solar physics. Title: SUSIM s 11-year Observational Record of the Solar UV Irradiance Authors: Floyd, L.; Cook, J.; Herring, L.; Crane, P. Bibcode: 2002cosp...34E.687F Altcode: 2002cosp.meetE.687F The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) aboard the Upper Atmosphere Research Satellite (UARS) has measured the solar UV spectral irradiance since October 1991. This 11-year solar cycle length period extends from a late secondary maximum of solar cycle~22 through the intervening solar minimum and ensuing maximum of solar cycle~23. Accordingly, SUSIM observed nearly the entire UV variation of both solar cycles. As is common for UV irradiance measurements, continuous instrumental responsivity changes during the experiment complicate irradiance determinations. SUSIM uses deuterium lamps and redundant optical channels to determine the changes in its responsivity since its last calibration before flight. The Mg~II coreto-wing ratio index, less resistant to these responsivity changes, is also measured. Accordingly, it has become a well used proxy for UV and even EUV variations at other wavelengths. Cyclic variations are mainly observed having periods corresponding to solar rotation and the solar cycle. The amplitude of these variations tend to be greater for shorter wavelengths and for emission lines. We explore the level of correspondence between the Mg~II index time series and those of the UV spectral irradiances. The wavelengthdependent variation of each of the two solar cycles is also are derived and compared. Intercomparisons with UV measurements from other experiments are presented, aiding in our understanding of both solar and instrumental effects. Title: Solar UV Spectral Irradiance Variation During Solar Cycle 23 Authors: Floyd, L. E.; Cook, J. W.; Crane, P. C.; Herring, L. C. Bibcode: 2001AGUFM.A51E0087F Altcode: The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) aboard the UARS has measured the solar spectral irradiance at UV wavelengths in the 115-410 nm range since October 1991. This period extends from a secondary maximum of solar activity before the decline of solar cycle~22, through the intervening solar minimum, and through the solar cycle~23 maximum. Accordingly, SUSIM has observed nearly the entire UV variation of both solar cycles. SUSIM uses deuterium lamps and redundant optical channels to determine changes in its responsivity since its final ground calibration more than ten years before the latest measurements. The new results for the wavelength-dependent variation of the solar UV spectral irradiance during solar cycle~23 will be presented. Trends in solar irradiance and in possible error sources are identified and analyzed. Emphasis will be placed on comparisons with variations observed during solar cycle~22 and on their relationship with solar indices (such as the MgII core-to-wing ratio). The rationale for continuing redundant and overlapping measurements of the solar UV irradiance will be provided. >http://wwwsolar.nrl.navy.mil/susim_uars.html</a> Title: Particles on Titan from the Stratopause to the Troposphere Authors: Griffith, C. A.; Hall, J. L.; Young, E. F.; Cook, J.; Rannou, P. Bibcode: 2001DPS....33.5301G Altcode: 2001BAAS...33.1135G We investigate Hubble Space Telescope images of three separate sources of particulates that vary temporally and spatially across Titan's disk. (1) North-south variations of Titan's albedo occur at visible wavelengths that result from seasonal changes in the number density of haze at Titan's stratopause (roughly 250 km altitude). The phase lag in these periodic variations match that of Titan's temperature field and support the hypothesis that the thermal profile reacts in concert with the wind field through the wind gradient equation. This coupling causes the thermal field to adjust to seasonal changes at a dynamical time scale of approximately 5 years, much longer than the radiative time scale. (2) Images at longer wavelengths (0.7-1 um) indicate the presence of particles near Titan's tropopause and lower stratosphere at high southern latitudes. The nature of these particles is unclear. Their absence at northern latitudes precludes a purely circulation origin. Their lack of measurable change from 1994 to 2000, precludes convective origins. (3) We detect one occurrence of a brightening at Titan's equator, unrelated to the stratosphere and the surface. Judging by its temporal nature and altitude of 20-40 km, this may an image of methane condensation clouds in Titan's atmosphere. This research is supported by the NASA Planetary Astronomy Program and the Hubble Space Telescope Program. Title: High-resolution Imaging of the Upper Solar Chromosphere: First Light Performance of the Very-high-Resolution Advanced ULtraviolet Telescope Authors: Korendyke, C. M.; Vourlidas, A.; Cook, J. W.; Dere, K. P.; Howard, R. A.; Morrill, J. S.; Moses, J. D.; Moulton, N. E.; Socker, D. G. Bibcode: 2001SoPh..200...63K Altcode: The Very-high-resolution Advanced ULtraviolet Telescope (VAULT) experiment was successfully launched on 7 May 1999 on a Black Brant sounding rocket vehicle from White Sands Missile Range. The instrument consists of a 30 cm UV diffraction limited telescope followed by a two-grating, zero-dispersion spectroheliograph tuned to isolate the solar Lα emission line. During the flight, the instrument successfully obtained a series of images of the upper chromosphere with a limiting resolution of ∼ 0.33 arc sec. The resulting observations are the highest-resolution images of the solar atmosphere obtained from space to date. The flight demonstrated that sub-arc second ultraviolet images of the solar atmosphere are achievable with a high-quality, moderate-aperture space telescope and associated optics. Herein, we describe the payload and its in-flight performance. Title: Solar EUV Variability as Measured by SOHO/EIT: Comparison to SOHO SEM and He II 304, Case Studies Authors: Newmark, J. S.; Cook, J. W.; McMullin, D. R. Bibcode: 2001AGUSM..SP32B06N Altcode: The specification of soft X-ray and EUV solar flux is important because it is the main ionizing source for the ionosphere and the EUV energy deposit is primarily responsible for the structure and dynamics of the thermosphere. The EIT instrument aboard SOHO obtains full disk images of the Sun through four channels at Fe IX,X (171 A), Fe XII (195 A), Fe XV (284 A), and He II (304 A). We construct a model differential emission measure (DEM) map, using calibrated SOHO EIT images from the four channels which accurately covers the temperature range 80,000 - 2.2 MK. We use the DEM map to calculate absolutely calibrated images of individual lines or passbands in addition to the four EIT channels. As a case study of the power of this technique we present a long term comparision (1996-2000) to the SOHO SEM instrument full disk irradiances. Additionally we produce a pure He II (304 A) solar irradiance for the entire SOHO EIT mission. This irradiance, covering a large part of a solar cycle can provide a fundamental parameter to compare with Earth's atmospheric variations. Title: In-flight Calibration of SOHO EIT Authors: Newmark, J. S.; Cook, J. W.; Auchere, F.; Moses, J. D.; Clette, F. Bibcode: 2001AGUSM..SP21B06N Altcode: The SOHO EIT response has varied both temporally and spatially throughout the mission. A large effort has been put forth into understanding instrument responsivity changes, the spectral response and absolute calibration. The latter two have been completed (Dere et al. 2000, Newmark 2000). The response degradation process consists of several components which are difficult to separate in detail. The two basic processes contributing to the degradation are 1) the absorption of EUV before it interacts with the CCD by a surface contaminant plus possible blackening of the entrance filter and 2) the reduction of charge collection efficiency (CCE) in the CCD due to EUV induced device damage. A method utilizing the in-flight calibration lamps has been developed which accurately characterizes the sensitivity changes. We present absolutely calibrated SOHO EIT data from 1996 - 2000. Title: Limb Brightening and Darkening of Solar Active Regions at Ultraviolet Wavelengths Determined from UARS/SUSIM Ultraviolet Irradiance Measurements Authors: Crane, P. C.; Floyd, L. E.; Herring, L. C.; Cook, J. W.; Prinz, D. K. Bibcode: 2001AGUSM..SP32B04C Altcode: We report the first quantitative measurements of the limb brightening and darkening of solar active regions at ultraviolet wavelengths, based upon Fourier analysis of the rotationally modulated mid-resolution (1.1- nm) ultraviolet irradiances measured by the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) on the Upper Atmospheric Research Satellite (UARS). Significant results have been obtained for the wavelength range 142-265 nm. We find weak limb brightening at short wavelengths and weak, perhaps insignificant, limb darkening at long wavelengths. Sharp transitions occur at the Si I and Al I edges at 168.2 nm and 207.6 nm, respectively, which bound a region of strong limb darkening. The quiet disk also exhibits weak limb brightening at short wavelengths, but has transitions to weak/medium and medium limb darkening at the Si I and Al I edges at 152.1 nm and 207.6 nm, respectively. Analysis of the Ly- (121.6 nm) index illustrates how the field-of-view response can introduce a significant instrumental effect to such measurements. This work was supported by NASA-Defense Purchase Requests S14798D and S10108X. Title: Measurements of 3-D Sunspot Coronal Magnetic Fields From Coordinated SOHO EUV and VLA Radio Observations Authors: Brosius, J. W.; Landi, E.; Cook, J. W.; Newmark, J.; Gopalswamy, N.; Lara, A. Bibcode: 2001AGUSM..SH32C02B Altcode: Three-dimensional sunspot coronal magnetograms were derived from coordinated extreme-ultraviolet (EUV) and radio observations of NOAA region 8108 (N21 E18) on 1997 November 18. The EUV spectra and images, obtained with the Coronal Diagnostic Spectrometer (CDS) and the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO) satellite, were used to derive differential emission measure (DEM) distributions for each spatial pixel (i.e., along each line of sight) of the region's images. These were subsequently used to calculate maps of the expected thermal bremsstrahlung brightness temperature at the Very Large Array (VLA) radio observing frequencies of 4.9 and 8.4 GHz. The thermal bremsstrahlung maps reproduce neither the structure nor the intensity of the observed maps, and indicate that thermal gyroemission must also contribute to the observed radio emission. Under the assumptions of a monotonic increase in temperature and a monotonic decrease in magnetic field strength with height above the sunspot, we derived the temperature distribution of the coronal magnetic field strength that reproduced simultaneously the observed right-hand and left-hand circularly polarized radio emission at 4.9 and 8.4 GHz for each spatial pixel in the sunspot maps. This was done by placing harmonics of the radio observing frequencies in appropriate plasma temperature intervals, integrating along the line of sight, and iterating until a solution was obtained. Magnetic field strengths corresponding to 3rd harmonic gyroemission at 4.9 GHz (580 Gauss) are found in coronal plasmas at temperatures as high as 2.2*E6 K, while magnetic field strengths corresponding to 2nd harmonic gyroemission at 8.4 GHz (1500 Gauss) are found in coronal plasmas at temperatures as high as 1.1*E6 K. Title: Comparison of Sac Peak Fe XIV Index with Model Index Computed from EIT Differential Emission Measure Maps Authors: Cook, J. W.; Newmark, J. S.; Altrock, R. C. Bibcode: 2001AGUSM..SP32B05C Altcode: We compare the Sac Peak Fe XIV green line index with a model index time series for the period of operations of the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO), covering the years 1996-2000, from cycle minimum to the peak of the current activity cycle 23. We compute a differential emission measure (DEM) map for each day using images from the four channels of EIT at 171 Å, 195 Å, 284 Å, and 304 Å. From the daily DEM map we then calculate a daily Fe XIV 5304 Å intensity image (see Cook et al. 1999, Proceedings of the 8th SOHO Workshop, ESA SP-446, pp. 241-246). The Sac Peak index is an average intensity, measured using a circular aperture 1 arcmin in diameter sampling the corona in 1 degree steps around disk center. It is taken at several different heights beyond the daily limb. We modeled the index values, for the aperture center at 1.15 Rodot from disk center, as the average intensity within a daily annulus covering 1.12 - 1.18 Rodot imposed on the model intensity image. We compare the observed index with our model results, and discuss in terms of the accuracy of the model intensities which can be determined from our EIT-based DEM curves. We actually produce a daily Fe XIV image for the entire EIT field-of-view. The Sac Peak index provides one well calibrated, long term check on the reliability of the DEM model calculation. This work has been supported by NASA under W-19,348, and by the Office of Naval Research. Title: Book Review: Observing the moon / Springer, 2000 Authors: Cook, J. Bibcode: 2001JBAA..111Q.110C Altcode: No abstract at ADS Title: School Cosmic Ray Outreach Detector (SCROD) Authors: Anchordoqui, L.; Cook, J.; MacLeod, J.; McCauley, T.; Moussienko, I.; Paul, T.; Reucroft, S.; Swain, J.; Terry, R. Bibcode: 2001ICRC....2..788A Altcode: 2001ICRC...27..788A; 2001hep.ex....6002A We report on our studies of applying novel detector technologies developed for LHC-era experiments to cosmic ray detection. In particular, we are investigating usage of scintillating tiles with embedded wavelength-shifting fibers and avalanche photodiode readout as part of a robust, inexpensive cosmic air shower detector. In the near future, we are planning to deploy detector stations based on this technology at area high schools and colleges as part of an outreach and education effort, known as SCROD. Title: Calibration and flight of the NRL EIT CalRoc Authors: Newmark, Jeffrey S.; Moses, J. Daniel; Cook, John W.; Delaboudiniere, Jean-Pierre; Song, Xueyan; Carabetian, Charles; Bougnet, Marie; Brunaud, Jacqueline; Defise, Jean-Marc; Clette, Frederic; Hochedez, Jean-Francois E. Bibcode: 2000SPIE.4139..328N Altcode: The ability to derive physical parameters of the Sun from observations by the Solar and Heliospheric Observatory (SOHO) Extreme Ultraviolet Imaging Telescope (EIT) greatly increases the scientific return of the mission. The absolute and time variable calibration of EIT therefore is of extreme interest. The NRL EIT Calibration Sounding Rocket (CalRoc) program was initiated to provide well calibrated, contemporaneous observations in support of SOHO EIT. These observations provide three benefits to the SOHO EIT data, absolute calibration points, temporal and spatial information of the EIT EUV response variability in flight via flat field information and clues to the physics of the degradation. Details of the bandpasses of the multilayered optics and the total telescope photometry are presented. Comparisons are shown with the contemporaneous images from SOHO EIT. Plans for the second CalRoc flight are discussed. Loss of reflectivity in the multilayer mirrors has been identified as a new component to the SOHO EIT and CalRoc degradation. Title: In-flight performance of the Very high Angular resolution ULtraviolet Telescope sounding rocket payload Authors: Korendyke, Clarence M.; Vourlidas, A.; Cook, John W.; Dere, Kenneth P.; Feldman, R.; Howard, Russell A.; Lilley, D. N.; Morrill, Jeff S.; Moses, J. Daniel; Moulton, Norman E.; Moye, Robert W.; Roberts, D. E.; Shepler, E. L.; Smith, J. K.; Socker, Dennis G.; Spears, T. R.; Waymire, R. S.; Brown, Wayne E.; Tarbell, Theodore D.; Berger, Tom; Handy, Brian N. Bibcode: 2000SPIE.4139..340K Altcode: The Very high Angular Resolution ULtraviolet Telescope experiment was successfully launched on May 7, 1999 on a Black Brant sounding rocket vehicle from White Sands Missile Range. The instrument consists of a 30 cm UV diffraction limited telescope followed by a double grating spectroheliograph tuned to isolate the solar Lyman (alpha) emission line. During the flight, the instrument successfully obtained a series of images of the upper chromosphere with a limiting resolution of approximately 0.33 arc-seconds. The resulting observations are the highest resolution images of the solar atmosphere obtained from space to date. The flight demonstrated that subarc-second ultraviolet images of the solar atmosphere are achievable with a high quality, moderate aperture space telescope and associated optics. Herein, we describe the payload and its in- flight performance. Title: High Angular Resolution Studies of Coronal Structures with SOHO Authors: Karovska, Margarita; Wood, Brian; Cook, John W.; Chen, James; Howard, Russ Bibcode: 2000Ap&SS.273....7K Altcode: Since January 1996, the Solar and Heliospheric Observatory (SOHO) has been providing unprecedented views of the extended solar corona to heliocentric distances of up to 32 solar radii. During the past three years we carried out studies of the morphology and dynamical evolution of various structures in the solar corona using two instruments on board SOHO: the Large Angle Spectrometric Coronagraph (LASCO) and the Extreme Ultraviolet Imaging Telescope (EIT). We have applied advanced image resolution enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in the solar corona. We describe here the results from these high-angular resolution studies, including of the kinematics of several Coronal Mass Ejections and polar jets. Title: Exploring Coronal Structures with SOHO Authors: Karovska, M.; Wood, B.; Chen, J.; Cook, J.; Howard, R. Bibcode: 2000JApA...21..403K Altcode: No abstract at ADS Title: Solar EUV Variability as Measured by SOHO/EIT Authors: Newmark, J. S.; Cook, J. W.; Moses, J. D.; Floyd, L. E. Bibcode: 2000SPD....31.0222N Altcode: 2000BAAS...32..814N The EIT instrument aboard SOHO obtains full disk images of the Sun through four channels at Fe IX,X (171 A), Fe XII (195 A), Fe XV (284 A), and He II (304 A). We construct a model differential emission measure (DEM) map, using the EIT images from the four channels which accurately covers the temperature range 80,000 - 2.2 MK. We use the DEM map to calculate absolutely calibrated images of individual lines or passbands in addition to the four EIT channels. The validity of our model is shown with a long term comparision to the SOHO SEM instrument full disk irradiances. An important application presented here is the time history from 1996-2000 of the pure He II (304 A) solar irradiance. Additional spatial and spectral comparisons can be done using the SOHO CDS instrument and the SERTS rocket flight. Title: Model for Radio Thermal Emission at 328 and 1446 MHz from EUV Observations Authors: Cook, J. W.; Newmark, J. S.; Vourlidas, A. Bibcode: 2000SPD....31.0221C Altcode: 2000BAAS...32..814C We have modeled the contribution to solar radio emission at 328 and 1446 MHz from free-free thermal bremsstrahlung emission, using a full disk differential emission measure (DEM) map of the Sun. The DEM map is produced from four EUV images (171 A, 195 A, 284 A, and 304 A) for a selected day from the EIT instrument on the SOHO satellite, using a method developed previously by Cook, Newmark, and Moses. The EIT instrument images the Sun out to 1.4 R, with a pixel size of 2.6 arc sec and spatial resolution of 2 pixels. We perform the radiative transfer calculation, determining the optical depth scale for free-free emission and the emergent absolute intensity for each pixel in the field-of-view using the individual DEM of that pixel, and transforming integrals over the line-of-sight into integrals over temperature via the DEM. We can compare our model calculation with the VLA radio observations of Vourlidas from 1998 January 31. Our model is in good agreement outside of active regions, where free-free emission should truly be the dominant emission mechanism. In areas such as sunspots, where the strong magnetic field leads to additional gyro resonance radiation, the difference between the observed total intensity and our calculated thermal component should be a good estimate of the nonthermal gyro radiation. This work is supported by NASA under W-19,348 and by the Office of Naval Research. Title: Search for Velocity Variations in Fe XIV 5304 A&ring Coronagraph Observations Near Activity Minimum Authors: Cook, J. W.; Socker, D. G.; Korendyke, C. M.; Howard, R. A.; Brueckner, G. E.; Karovska, M.; Wood, B. E. Bibcode: 2000AdSpR..25.1883C Altcode: The LASCO C1 coronagraph on the SOHO satellite observes the solar corona from 1.1 to 3.0 Ro, and contains a Fabry-Perot interferometer which can image the corona in the 1.8 million K Fe XIV green line. We designed an observing program with reduced spatial coverage and reduced profile coverage at only three wavelengths to study coronal heating in off-limb structures at high temporal resolution. We illustrate the observations from 31 March 1997 of a bright loop system above an active region off the northeast limb Title: Coronal Thermal Structure from a Differential Emission Measure Map of the Sun Authors: Cook, J. W.; Newmark, J. S.; Moses, J. D. Bibcode: 1999ESASP.446..241C Altcode: 1999soho....8..241C We have developed a procedure to produce a differential emission measure (DEM) map of the Sun using images from the four channels of the EIT instrument at 171 (Fe IX/X), 195 (Fe XII), 284 (Fe XV), and 304 A (He II). We use images from the EIT CalRoc sounding rocket flight on 16 October 1997. Our DEM procedure could also be applied to calibrated SOHO EIT images and to TRACE observations. We find a statistical relation between brightness of solar features (for example in the 171 A image) and increasing slope of the DEM in the temperature range log T = 5.5 to 6.0. In their thermal structure active regions are not just areas brighter than quiet areas whose DEM distributions continue to rise to even hotter temperatures, but have greater relative amounts of hotter material to cooler material toward 1 M K and above than do quiet areas. The DEM should not be modeled in terms of an average structure, either plane parallel or with loop geometry. Since at least the time of the SO82A spectroheliograph observations from Skylab it has been clear that structures observed in the temperature range of any one line differ from structures observed in a hotter or cooler line. Any DEM distribution is obtained from intensity observations through all structures in the line of sight, and is composed from the combined individual DEM distributions of these structures. We interpret the DEM map in terms of ensembles of individual loops of differing temperatures, where the ensembles are characteristically different in quiet and active areas of the Sun. This work is supported by NASA under DPR S-92385-D and by the Office of Naval Research. Title: Kinematic Measurements of Polar Jets Observed by the Large-Angle Spectrometric Coronagraph Authors: Wood, B. E.; Karovska, M.; Cook, J. W.; Howard, R. A.; Brueckner, G. E. Bibcode: 1999ApJ...523..444W Altcode: We analyze polar jets observed by the Large-Angle Spectrometric Coronagraph (LASCO) instrument aboard the Solar and Heliospheric Observatory. The events studied here are from 1997 March 24 and August 5. The main objective of our analysis is to determine whether the jets' motions are consistent with ballistic behavior. Although ballistic trajectories have some success in fitting the observed kinematic motions, there is substantial evidence that gravity alone is not regulating the movement of the jets. First of all, the August 5 events appear to exhibit slight accelerations rather than decelerations above 3 Rsolar. Second, all the events studied here have very similar velocities, suggesting that by the time the jets reach the LASCO field of view, the jets have been incorporated into the ambient solar wind. If this is the case, the jets could be very useful as tracers of the solar wind at low heights in the Sun's polar regions. Title: Comparing the kinematic properties of CMEs observed by LASCO and EIT with models of erupting flux ropes Authors: Wood, B. E.; Karovska, M.; Chen, J.; Brueckner, G. E.; Cook, J. W.; Howard, R. A. Bibcode: 1999AIPC..471..633W Altcode: 1999sowi.conf..633W We present observations of three coronal mass ejections (CMEs) observed by the LASCO and EIT instruments aboard the Solar and Heliospheric Observatory. The three CMEs are from 1997 February 23, 1997 April 30, and 1998 March 6. The February 23 CME is accompanied by a spectacular prominence eruption and its leading edge reaches velocities of about 900 km s-1. The April 30 and March 6 CMEs have no apparent accompanying prominence eruptions and attain more modest velocities of about 300 and 600 km s-1, respectively. Despite their kinematic differences, all three CMEs have bright, roughly circular rims which can be interpreted as marking the apexes of expanding magnetic flux ropes, and all three can be tracked from their origins near the surface of the Sun out to great distances. We compare the kinematic and morphological properties of these CMEs with an MHD model of an erupting flux rope, and we find that the CMEs can be successfully modeled in this manner. Title: LASCO observations of the solar polar regions Authors: Karovska, M.; Wood, B. E.; Brueckner, G. E.; Cook, J. W.; Howard, R. A. Bibcode: 1999AIPC..471..309K Altcode: 1999sowi.conf..309K We describe our study of the dynamical properties of coronal structures in the polar regions of the Sun using a sequence of 200 LASCO/C2 images. This sequence was designed to study polar outflows in general, in both polar plumes and in interplume regions. The results of our analyses show that such studies are complicated by the existence of foreground material, especially when high latitude streamer material rotates into the field of view. We also describe our analysis of the kinematic properties of several polar jets. The results suggest that polar jets might be used for studies of the outflow wind velocities in coronal holes at heights above several solar radii. Title: Coronal Thermal Structure from a Differential Emission Measure Map of the Sun Authors: Cook, J. W.; Newmark, J. S.; Moses, J. D. Bibcode: 1999AAS...19410003C Altcode: 1999BAAS...31..996C We have developed a procedure to produce a differential emission measure (DEM) map of the Sun using images from the four channels of the EIT instrument at 171 (Fe IX/X), 195 (Fe XII), 284 (Fe XV), and 304 A (He II). We use images from the EIT CalRoc sounding rocket flight on 16 October 1997. Our DEM procedure could also be applied to calibrated SOHO EIT images and to TRACE observations. We find that the slope of the DEM distribution over the temperature range log T = 5.5 to 6.0 is typically near +1 for quiet areas, but is +3/2 for active regions. In their thermal structure active regions are not just areas brighter than quiet areas whose DEM distributions continue to rise to even hotter temperatures, but have greater relative amounts of hotter material to cooler material toward 1M K and above than do quiet areas. The DEM should not be modeled in terms of an average structure, either plane parallel or with loop geometry. Since at least the time of the SO82A spectroheliograph observations from Skylab it has been clear that structures observed in the temperature range of any one line differ from structures observed in a hotter or cooler line. Any DEM distribution is obtained from intensity observations through all structures in the line-of-sight, and is composed from the combined individual DEM distributions of these structures. We interpret the DEM map in terms of ensembles of individual loops of differing temperatures, where the ensembles are characteristically different in quiet and active areas of the Sun. This work is supported by NASA under DPR S-92385-D and by the Office of Naval Research. Title: Comparison of Two Coronal Mass Ejections Observed by EIT and LASCO with a Model of an Erupting Magnetic Flux Rope Authors: Wood, B. E.; Karovska, M.; Chen, J.; Brueckner, G. E.; Cook, J. W.; Howard, R. A. Bibcode: 1999ApJ...512..484W Altcode: We present observations of two coronal mass ejections (CMEs) observed by the LASCO and EIT instruments on board the Solar and Heliospheric Observatory. One was observed on 1997 April 30 and the other on 1997 February 23. The latter CME is accompanied by a spectacular prominence eruption and reaches velocities of about 900 km s-1, while the former has no apparent accompanying prominence eruption and attains velocities of only about 300 km s-1. However, the two CMEs are similar in appearance, having bright circular rims that can be interpreted as marking the apexes of expanding magnetic flux ropes, and both can be tracked from their origins near the surface of the Sun out to great distances. We compare the kinematic and morphological properties of these CMEs with an MHD model of an erupting flux rope and find that the CMEs can be successfully modeled in this manner. Title: Study of Dynamical Properties of Coronal Structures in the Polar Regions Authors: Karovska, Margarita; Wood, Brian E.; Cook, John W.; Howard, Russell A.; Brueckner, Guenter E. Bibcode: 1999SSRv...87..219K Altcode: We present the results from a study of the dynamical properties of polar jets in the Sun's polar regions using LASCO C2 coronagraph and EIT observations. In the simplest impulsive acceleration scenarios for jets, gravity is expected to be the dominant force on the jet following the initial acceleration, especially in the Sun's polar regions where the open magnetic fields should not significantly impede the jet's motion. Our analysis shows that although at low heights the kinematics of the jets could be consistent with a gravitational deceleration of the ejected plasma, at higher heights their motions may simply follow the ambient solar wind outflow. If so, the polar jets can be used as tracers of the solar wind in coronal holes. Title: Search for Brightness Variations in Fe XIV Coronagraph Observations of the Quiescent Solar Corona Authors: Wood, B. E.; Karovska, M.; Cook, J. W.; Brueckner, G. E.; Howard, R. A.; Korendyke, C. M.; Socker, D. G. Bibcode: 1998ApJ...505..432W Altcode: We use Fe XIV 5303 Å green line images obtained by the Large Angle Spectrometric Coronagraph (LASCO) on board SOHO to search for variability in the quiescent solar corona in the shortest observable timescales. The observing program obtained Fe XIV images of a small area of the inner corona every 2 minutes over a period of 1 hr. We present results from two executions of this program taken several months apart. The most obvious variability observed in the two sequences is in the form of quasi-steady brightening on timescales of at least an hour. Of particular interest are two compact loops that are observed to vary significantly during the course of the observations. Superposed on the long-term brightening in these loops are statistically significant variations on timescales of about 30 minutes. In both loops, the overall brightening is greatest at the apparent loop tops, where the intensity increases by at least 25%. In one loop there appears to be a flow up one of the legs of the loop. We place these observations in context with earlier observations of coronal variability, and we discuss the energy requirements for the observed brightening. Emission measures computed from Fe XIV intensities measured within the two brightening loops are over an order of magnitude lower than those typically found for active regions on the solar disk, which suggests significantly lower average densities. For one of the loops, we measure densities in the range ne = (5.0-7.4) × 108 cm-3. Lower than average densities are expected for the two loops, given that they reach more than 1 pressure scale height above the solar limb. Title: Magnetic Sources of the Solar Irradiance Cycle Authors: Lean, J. L.; Cook, J.; Marquette, W.; Johannesson, A. Bibcode: 1998ApJ...492..390L Altcode: Using recently processed Ca K filtergrams, recorded with a 1 Å filter at the Big Bear Solar Observatory (BBSO), we quantitatively assess the component of solar irradiance variability attributable to bright magnetic features on the Sun's disk. The Ca K filtergrams, ``flattened'' by removing instrumental effects and center-to-limb variations, provide information about bright sources of irradiance variability associated with magnetic activity in both active regions and dispersed active region remnants broadly distributed in the supergranule network (termed collectively ``faculae''). Procedures are developed to construct both total and UV spectral solar irradiance variations explicitly from the processed Ca K filtergrams, independently of direct irradiance observations. The disk-integrated bolometric and UV facular brightness signals determined from the filtergrams between late 1991 and mid-1995 are compared with concurrent solar irradiance measurements made by high-precision solar radiometers on the Upper Atmosphere Research Satellite (UARS). The comparisons suggest that active-region and active-network changes can account for the measured variations. This good agreement during a period covering most of the decline in solar activity from the cycle 22 maximum to the impending solar minimum directly implicates magnetic features as the sources of the 11 yr irradiance cycle, apparently obviating the need for an additional component other than spots or faculae. Title: White-Light Coronal Mass Ejections: A New Perspective from LASCO Authors: St. Cyr, O. C.; Howard, R. A.; Simnett, G. M.; Gurman, J. B.; Plunkett, S. P.; Sheeley, N. R.; Schwenn, R.; Koomen, M. J.; Brueckner, G. E.; Michels, D. J.; Andrews, M.; Biesecker, D. A.; Cook, J.; Dere, K. P.; Duffin, R.; Einfalt, E.; Korendyke, C. M.; Lamy, P. L.; Lewis, D.; Llebaria, A.; Lyons, M.; Moses, J. D.; Moulton, N. E.; Newmark, J.; Paswaters, S. E.; Podlipnik, B.; Rich, N.; Schenk, K. M.; Socker, D. G.; Stezelberger, S. T.; Tappin, S. J.; Thompson, B.; Wang, D. Bibcode: 1997ESASP.415..103S Altcode: 1997cpsh.conf..103S No abstract at ADS Title: LASCO Observations of Variability in the Quiescent Solar Corona Authors: Wood, B. E.; Karovska, M.; Cook, J. W.; Brueckner, G. E.; Howard, R. A. Bibcode: 1997AAS...191.7303W Altcode: 1997BAAS...29Q1321W We discuss the localized small scale coronal variability detected in observations made by the Large Angle Spectrometric Coronagraph (LASCO) onboard SOHO. The LASCO C1 coronagraph was used to take images of small portions of the solar corona located in the streamer belt between roughly 1.1 and 2.0 Rsun. Two sets of images were obtained several months apart. Each set contains images taken with LASCO's Fabry-Perot interferometer centered on the Fe XIV lambda 5303 line, and in the nearby continuum. The images were obtained about once every minute. Significant variability was detected in two compact loops, one in each sequence, which brighten at their tops by about 10% in one hour. In one of the loops, there appears to be a flow up one leg of the loop with a velocity of 100--200 km s(-1) . The quiescent loop-top brightenings are reminiscent of transient loop-top brightenings seen in Yohkoh soft X-ray observations of the quiescent Sun and during flares. Title: Ultraviolet Irradiance at Solar Minimum Authors: Floyd, L. E.; Crane, P. C.; Herring, L. C.; Cook, J. W.; Prinz, D. K.; Brueckner, G. E. Bibcode: 1997AAS...191.7409F Altcode: 1997BAAS...29.1325F The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) aboard the Upper Atmosphere Research Satellite has been measuring the sun's UV spectral irradiance for wavelengths from 115 to 410 nm since October 1991. We describe the behavior of the solar UV spectral irradiance during the decline of solar cycle 22 with special emphasis on the recent solar minimum period. Although the time series of the spectral irradiances have behavior similar to that of the Mg II core-to-wing ratio, there are differences among them. We describe the behavior near solar minimum of both the irradiance in selected UV wavelength intervals, the the Mg II core-to-wing ratio, and the integrated Ly-alpha line irradiance. Overall, each of these time series follows a similar pattern: a broad and flat minimum, with some 27-day solar rotation modulation still evident at nearly all times. The date found for solar minimum is often used as an input parameter used in predicting the timing of the following solar cycle maximum. The minimum strongly depends on both the algorithm and the averaging time period used. For sunspot number, the generally accepted minimum is defined as the lowest value of a 12-month running average of monthly averages of daily values. We analyze various methods for finding the solar minimum in the UV including that used for sunspot number. For wavelengths longer than the Al edge at 208 nm, systematic errors due to instrument responsivity degradation ( ~ +/-1%) become a significant fraction of the long-term variation during the minimum, making determination of the date of the minimum increasingly uncertain. We find that the minimum for Mg II occurs during April 1996 while that for Ly-alpha occurs later, during October 1996. These results are compared with solar minimum behavior of other solar indices to better understand the relationship among the regions of the solar atmosphere where each emission originates. Title: Image Processing of December 23 1997 LASCO CME Observations Authors: Karovska, M.; Wood, B. E.; Brueckner, G. E.; Cook, J. W.; Howard, R. A.; Andrews, M. D. Bibcode: 1997SPD....28.0126K Altcode: 1997BAAS...29..884K The Large Angle Spectrometric Coronagraph (LASCO) onboard SOHO contains three individual coronagraphs, C1, C2, and C3, that image the solar corona from 1.1 R_sun to 32 R_sun. Since January 1996, LASCO has detected a number of CMEs. Starting on December 23 1996 several spectacular CME events were observed with all LASCO coronagraphs. The onset was detected with both EIT and LASCO/C1 instruments. The images of the developing CMEs contain many complex components with different spatial scales and a wide range of contrast levels. Spatial and temporal characterization of these structures is extremely important for understanding the origin and the early evolution of CMEs. To extract information on the low contrast small-scale structures in the CMEs we applied image processing techniques to several time sequences of images. Our study of the movies made from these contrast and/or resolution enhanced images leads to a better knowledge of the morphology and temporal evolution of the small scale structures, especially at the onset of the CME as observed with the C1 and EIT. LASCO is a cooperative project of an international group of scientists at the Naval Research Laboratory, Washington, DC, the Max-Planck Institut fur Aeronomie, Germany, the Laboratoire d'Astronomie Spatiale, France, and the Space Research Group at the University of Birmingham, Great Britain. Title: Search for Velocity Signatures of Energy Release in Fine Scale Coronal Features Authors: Cook, J. W.; Socker, D. G.; Korendyke, C. M.; Howard, R. A.; Karovska, M. Bibcode: 1997SPD....28.0119C Altcode: 1997BAAS...29..882C The Large Angle Spectrometric Coronagraph (LASCO) on the SOHO satellite consists of three individual coronagraphs with nested fields of view. The innermost C1 coronagraph observes the solar corona from 1.1 to 3.0 R_⊙, and contains a Fabry Perot interferometer which can image the corona in the 1.8 million K Fe XIV emission line at 5303 Angstroms with 0.7 Angstroms resolution. We designed an observing program with reduced spatial coverage and reduced profile coverage at only three wavelengths (line center and the half power points of the thermal plus instrumental profile) in order to increase the observing cadence. From these observations we can construct maps of the observed field in integrated line intensity, doppler velocity shift, and nonthermal broadening. We can thus search for signatures of coronal heating such as transient brightenings, bulk velocity flows, or nonthermal turbulent line broadening at spatial scales down to 11 arc sec (two CCD pixels), with temporal resolution of 4 minutes. We have run this program several times so far, and will report on early results. Title: Ultraviolet Jets and Bright Points in the Solar Chromosphere. II. Statistical Correlations Authors: Hoekzema, N. M.; Rutten, R. J.; Cook, J. W. Bibcode: 1997ApJ...474..518H Altcode: We use HRTS-VI rocket observations of the solar chromosphere to search for relationships between high-Dopplershift ``jets'' observed in the C I lines near λ = 156 nm and internetwork ``bright points'' observed in the λ = 160 nm continuum, in sequel to the analysis by Cook et al. which failed to find a direct connection between these phenomena. We now use the same data to establish statistical correlations between C I Dopplershift and 160 nm brightness modulation in internetwork areas. These mean relations emerge only after extensive spatial averaging and have small amplitude, but are definitely significant. They show that both C I Dopplershift and 160 nm brightness participate in oscillatory behavior with 3 minute periodicity and mesoscale (8 Mm wavelength) as well as small-scale (1.4 Mm wavelength) spatial patterning. We find spatial and temporal phase relations between Dopplershift and brightness that confirm that jets and bright points should not be interpreted as isolated entities. Rather, they are chromospheric manifestations, with much pattern interference, of the oscillatory acoustic shock dynamics in the internetwork which also cause Ca II K2V grains. Additional small-scale modulation is present which we attribute to waves with f-mode character. Title: Enhancing the Spatial Resolution of Solar Coronagraph Observations Using Dynamic Imaging Authors: Zaccheo, T. S.; Karovska, M.; Cook, J. W.; Howard, R. A.; Brueckner, G. E.; Korendyke, C. M.; Schwenn, R. Bibcode: 1996ApJ...471.1058Z Altcode: The Large Angle Spectrometric Coronagraph (LASCO) Cl coronagraph on board the Solar and Heliospheric Observatory (SOHO) is designed to image the corona from 1.1 to 3.0 Rsun. The resolution of C1 is defined by the size of its CCD pixels, which correspond to 5".6, and not by the diffraction limit of the optical system, which may be as small as 3". The resolution of Cl can be improved using the technique of "dynamic imaging" the process of acquiring successive images of the same scene using sub- pixel displacements of the steerable primary mirror. We developed a technique we call the fractional pixel restoration (F PR) algorithm that utilizes these observations to construct an image with improved resolution. Simulations were used to test this algorithm and to explore its limitations. We also applied the direct co-addition and FPR algorithms to laboratory preffight images of a wire mesh grid. These results show that the resolution of the C1 coronagraph can be significantly enhanced, even in the presence of noise and modest differences between successive images. In some cases, the results can even reach the diffraction limit of the telescope. Title: STEREO: a solar terrestrial event observer mission concept Authors: Socker, Dennis G.; Antiochos, S. K.; Brueckner, Guenter E.; Cook, John W.; Dere, Kenneth P.; Howard, Russell A.; Karpen, J. T.; Klimchuk, J. A.; Korendyke, Clarence M.; Michels, Donald J.; Moses, J. Daniel; Prinz, Dianne K.; Sheely, N. R.; Wu, Shi T.; Buffington, Andrew; Jackson, Bernard V.; Labonte, Barry; Lamy, Philippe L.; Rosenbauer, H.; Schwenn, Rainer; Burlaga, L.; Davila, Joseph M.; Davis, John M.; Goldstein, Barry; Harris, H.; Liewer, Paulett C.; Neugebauer, Marcia; Hildner, E.; Pizzo, Victor J.; Moulton, Norman E.; Linker, J. A.; Mikic, Z. Bibcode: 1996SPIE.2804...50S Altcode: A STEREO mission concept requiring only a single new spacecraft has been proposed. The mission would place the new spacecraft in a heliocentric orbit and well off the Sun- Earth line, where it can simultaneously view both the solar source of heliospheric disturbances and their propagation through the heliosphere all the way to the earth. Joint observations, utilizing the new spacecraft and existing solar spacecraft in earth orbit or L1 orbit would provide a stereographic data set. The new and unique aspect of this mission lies in the vantage point of the new spacecraft, which is far enough from Sun-Earth line to allow an entirely new way of studying the structure of the solar corona, the heliosphere and solar-terrestrial interactions. The mission science objectives have been selected to take maximum advantage of this new vantage point. They fall into two classes: those possible with the new spacecraft alone and those possible with joint measurements using the new and existing spacecraft. The instrument complement on the new spacecraft supporting the mission science objectives includes a soft x-ray imager, a coronagraph and a sun-earth imager. Telemetry rate appears to be the main performance determinant. The spacecraft could be launched with the new Med-Lite system. Title: Enhancing the spatial resolution of solar coronagraph images using dynamic imaging Authors: Karovska, M.; Zaccheo, T. S.; Cook, John W.; Brueckner, Guenter E.; Howard, Russell A. Bibcode: 1996SPIE.2804..175K Altcode: The LASCO C1 mirror coronagraph onboard the SOHO satellite (launched on 2 December 1995) was designed to observe the fine structure of the solar corona from 1.1 to 3.0 R. Even though the optical resolution is approximately 3 arc sec, the nominal achieved resolution is set by the CCD pixel size of 5.6 arc sec. A pixel size of 1.5 arc sec or less is needed to obtain diffraction limited observations according to the Nyquist criteria, and therefore the actual coronagraph images are under sampled by a factor of 4. We have explored improving the spatial resolution of the LASCO C1 images using the technique of dynamic imaging. Successive images are obtained with sub-pixel displacements of the steerable primary mirror. Typically a set of 4 images is obtained with 1/2 pixel displacements in the x and y axes. Using simulated data we have studied the improvement resulting both from simple co-addition of the multiple observations, and from a deconvolution algorithm we call Fractional Pixel Restorations (FPR). We studied the effects in numerical simulations of noise, contrast variations, modest differences in the scene observed in the multiple images, etc. WE have also applied co-addition and the FPR algorithm to laboratory pre-flight images of a wire mesh target, which significantly improved the resolution. Using dynamic imaging with 16 images and 1/4 pixel steps, it would in principle be possible to reach the diffraction limit of the telescope in some circumstances (low noise, sufficient image contrast, no temporal changes in the observed scene, a well characterized instrumental point response function). By the time of this meeting we hope to have high resolution solar images from the LASCO C1 telescope to show. LASCO is a cooperative project of an international group of scientists at the Naval Research Laboratory, Washington, DC, the Max- Planck Institute fur Aeronomie, Germany, the Laboratoire d'Astronomie Spatiale, France, and the Space Research Group at the University of Birmingham, Great Britain. Title: Ultraviolet Jets and Bright Points in the Solar Chromosphere. I. Search for One-to-One Relationships Authors: Cook, J. W.; Rutten, R. J.; Hoekzema, N. M. Bibcode: 1996ApJ...470..647C Altcode: Ultraviolet spectrograms and spectroheliograms of the solar chromosphere are used to test the suggestion of Dere, Bartoe, & Brueckner and Rutten & Uitenbroek that bright points in quiet Sun cell interiors observed at = 1600 A, chromospheric jets observed in C I lines near λ = 1560 Å, and Ca II K2v bright points are associated with each other and that they are all manifestations of the same wave interaction in the nonmagnetic chromosphere. We search for spatio-temporal connections between 1600 Å bright points and C I blue jets using data from the High Resolution Telescope and Spectrograph VI rocket flight, comparing 1600 A spectrohellograms and a cospatial C I Doppler shift map on a pixel-by-pixel basis. We find no direct evidence for spatial colocation of bright points and jets, not for instantaneous correspondence and also not when allowing for phase delays as long as 3 minutes. Also, the average brightness evolution and its rms fluctuation are not obviously different between sites of large C I blueshift and the remaining surface. Title: LASCO Observations of the 03Feb96 Streamer Blow-out Authors: Andrews, M. D.; Korendyke, C. M.; Koomen, M. J.; Brueckner, G. E.; Cook, J. W.; Dere, K. P.; Howard, R. A.; Michels, D. J.; Moses, J. D.; Morrill, J. S.; Moulton, N. E.; Paswaters, S. E.; Socker, D. G.; St. Cyr, O. C. St.; Wang, D.; Lamy, P. L.; Llebaria, A.; Bout, M. V.; Schwenn, R.; Podlipnik, B.; Bedford, D. K.; Biesecker, D. A.; Eyles, C. J.; Plunkett, S.; Simnett, G. M. Bibcode: 1996AAS...188.3716A Altcode: 1996BAAS...28..880A The C2 and C3 telescopes on the Large Angle Spectrometric Coronograph (LASCO) have recorded images of a Streamer Blow-out which occured on 03Feb96. We will present a series of images produces by combining data from the 2 coronographs. These images show a rapid evolution of the coronal streamer belt over projected distances of 2 to 20 solar radii. The streamer belt shows a dramatic brightening, which is seen to propagate outward. A bubble-like structure is seen to move away from the Sun and expand. At the end of this event, the equatorial corona is significantly less bright than prior to the event. Title: LASCO Observations of the Solar Corona to 32 Rsun Authors: Cook, J. W.; Koomen, M. J.; Korendyke, C. M.; Brueckner, G. E.; Dere, K. P.; Howard, R. A.; Michels, D. J.; Morrill, J. S.; Moses, J. D.; Socker, D. G.; Paswaters, S. E.; Wang, D.; Moulton, N. E.; Cyr, O. C. St.; Andrews, M. D.; Schwenn, R.; Podlipnik, B.; Lamy, P. L.; Llebaria, A.; Bout, M. V.; Simnett, G. M.; Bedford, D. K.; Eyles, C. J.; Plunkett, S.; Biesecker, D. A. Bibcode: 1996AAS...188.3717C Altcode: 1996BAAS...28..880C The Large Angle Spectrometric Coronagraph (LASCO) was launched on board the SOHO satellite on 2 December 1995. The C3 externally-occulted coronagraph of LASCO observes the solar corona over a field from 3.7-32 R_ ⊙, using a 1024x1024 CCD detector with a pixel size corresponding to 56 arc sec. Observations can be made using color filters ranging from the blue (420-520 nm) to the near-IR (860-1050 nm), and through polarizing filters. We report on early observations of the solar corona out to 32 Rsun. Title: Facular Origin of the Sun's 11-year Total Radiation Cycle Authors: Lean, J.; Cook, J.; Marquette, W.; Johannesson, A.; Willson, R. Bibcode: 1996AAS...188.7901L Altcode: 1996BAAS...28Q.955L While the amplitude and temporal structure of the 11-year cycle in the Sun's total radiation is relatively well established from spacebased radiometry, the origins of the variations are not. Rotational modulation on shorter time scales is attributable to the changing presence on the Sun's Earth-facing disk of dark sunspots and bright faculae, both of which occur frequently during times of high solar activity but may be absent for days during solar minimum conditions. However, calculations of the energy changes in sunspots and active region faculae over the longer time scale of the 11-year cycle underestimate the observed solar cycle irradiance modulation by about a factor of two. This apparent lack of facular brightness has lead to speculation of a missing irradiance brightness component, and the possibility that a non facular -- perhaps global -- mechanism may be responsible for the observed total radiation energy changes. Recent analysis of Ca K filtergrams, recorded with a 1 Angstrom Daystar filter at the BBSO, suggest a methodology with which to quantitatively assess the contribution of facular brightness to total solar irradiance variations. Following removal of instrumental effects and limb variations from the Ca K images, the resultant "flattened" spectroheliograms provide a surrogate for facular brightness in both active regions and in the surrounding chromospheric network. Evolution of the globally integrated signal from enhanced Ca K emission on the full solar disk is compared with concurrent total solar irradiance measurements made by the ACRIM II radiometer on the Upper Atmosphere Research Stellite from 1992 to 1994. This period covers most of the decline in solar activity from the cycle 22 maximum to the impending solar minimum, and suggest that facular changes can account for essentially all the measured variations. Title: Preliminary Photometric Calibration of LASCO C3 Coronagraph Images using Pre-Flight Laboratory Images of Standard Sources and In-Flight Images of Standard Stars Authors: Korendyke, C. M.; Koomen, M. J.; Andrews, M. D.; Brueckner, G. E.; Cook, J. W.; Dere, K. P.; Howard, R. A.; Michels, D. J.; Moses, J. D.; Morrill, J. S.; Moulton, N. E.; Paswaters, S. E.; Socker, D. G.; St. Cyr, O. C.; Wang, D.; Lamy, P. L.; Llebaria, A.; Bout, M. V.; Schwenn, R.; Podlipnik, B.; Bedford, D. K.; Biesecker, D. A.; Eyles, C. J.; Plunkett, S.; Simnett, G. M. Bibcode: 1996AAS...188.3621K Altcode: 1996BAAS...28..876K The C3 coronagraph is a wide field (+/-8.0 degrees), externally occulted, white light coronagraph. The instrument is one of three coronagraphs comprising the Large Angle Spectrometric COronagraph (LASCO) experiment mounted on the Solar Heliospheric Observatory satellite. The satellite was launched on Dec. 2, 1996; C3 observations began in early Jan. 1997. The coronagraph optical train includes a set of five broadband color filters mounted in a wheel. Prior to flight, an image was obtained through each color filter of a well characterized, rear-illuminated, opal glass diffusing screen. The C3 in-flight images, in addition to the coronal structures, also contain several hundred bright stars. We present a comparison of the photometric calibration derived from standard stars with the laboratory measurements. The resulting calibration is then used to examine color variations in the white light corona over the field of view. The LASCO experiment was developed by a scientific consortium of members from NRL (USA), MPAe (Germany), LAS (France) and U. Birmingham (United Kingdom). Title: Comparison of solar flare emission measures from broadband soft X-ray and ultraviolet spectrograph observations Authors: Cook, J. W.; Waljeski, K.; Moses, D.; Bruechner, G. E. Bibcode: 1996AdSpR..17d.101C Altcode: 1996AdSpR..17..101C Joint observations of a solar flare were obtained by the AS&E Imaging X-ray Telescope and the NRL High Resolution Telescope and Spectrograph (HRTS). We compare emission measures from soft X-ray and HRTS data. A small isolated X-ray loop close to the HRTS slit position has an emission measure n_e^2DeltaL of 3.5x10^29 cm^-5, compared to an emission measure of 2.7x10^29 cm^-5 obtained from the intensity of flaring Fe XXI 1354 Angstroms plasma along the HRTS slit. Title: Enhancing the Spatial Resolution of LASCO/C1 Observations Authors: Zaccheo, T. S.; Karovska, M.; Brueckner, G.; Cook, J. W.; Howard, R. Bibcode: 1995AAS...18712208Z Altcode: 1995BAAS...27.1454Z The LASCO C1 coronagraph was designed to examine the fine structure of the solar corona in the region from 1.1R_sun to 3R_sun. Even though the diffraction limit of the telescope is ~ 3\arcsec, the nominal resolution is set by the CCD pixels (5.6''/). A pixel size of 1.5''/ or smaller is needed in order to obtain diffraction limited observations (according to the Nyquist criterium). Therefore, the resulting images are undersampled by a factor of approximately 4. Some of this lost resolution can be recovered by acquiring successive observations using sub-pixel displacements of the steerable primary mirror incorporated into the LASCO/C1 design (``Dynamic Imaging''). The spatial resolution of the LASCO/C1 coronagraph can be enhanced by combining or co-adding multiple observations separated by fractions of a pixel. We have identified several methods for constructing sub-pixel estimates, evaluated the performance of simple co-addition techniques, and developed an improved algorithm for obtaining fractional pixel restorations. Simulations were used to test this algorithm and to explore its limitations. In this presentation, we describe the algorithm and the results of these simulations. The results show that the resolution of the C1 coronagraph can be enhanced, even in the presence of significant noise and modest differences between successive observations. Title: The O IV and S IV Intercombination Lines in Solar and Stellar Ultraviolet Spectra Authors: Cook, J. W.; Keenan, F. P.; Dufton, P. L.; Kingston, A. E.; Pradhan, A. K.; Zhang, H. L.; Doyle, J. G.; Hayes, M. A. Bibcode: 1995ApJ...444..936C Altcode: New calculations of O IV electron density diagnostic emission-line ratios involving the 1399.8, 1401.2, 1404.8, and 14076.4 A transitions are presented. A comparison of these calculations with observational data from a quiet solar region, a sunspot, and an active region obtained with the High Resolution Telescope and Spectrograph (HRTS), two flares observed with the SO82B spectrograph on board Skylab, and Hubble Space Telescope (HST) observations by the Goddard High Resolution Spectrograph (GHRS) of Capella, gives good results using the ratio R1 = I(1407.4 A)/I(1401.2 A). However, the electron density obtained using the ratio R2 = I(1407.4 A)/I(1404.8 A) is often an order of magnitude smaller. The O IV 1404.8 A line is blended with the S IV 1404.8 A line, and we investigate whether this ratio may still be used as a density diagnostic if the S IV 1406.1 A line intensity is used to correct for the presence of S IV 1404.8 A, using previous S IV calculations by Dufton et al. We still find systematic differences compared to density determinations from line ratios that do not involve the O IV 1404.8 A line, which we suggest are due to errors in earlier theoretical calculations of the S IV atomic data, and also possibly to previously unconsidered fluorescent pumping of the upper level of the S IV 1404.8 A transition. Title: The Moon. Authors: Cook, J. Bibcode: 1995oaa..conf...45C Altcode: Instruments, the observation, occultations, recording the observation are discussed. Title: Model For Variability of the Solar Far Ultraviolet Flux Using Full Disk Magnetograms Authors: Cook, J. W.; Brueckner, G. E.; Prinz, D. K.; Floyd, L. E.; Lund, P. A. Bibcode: 1994AAS...18512307C Altcode: 1994BAAS...26R1523C The variability of the solar full disk flux in the 1175-2100 Angstroms wavelength range is largely determined from the surface distribution on the Sun of active regions, whose increase and decrease over the solar cycle, and passage across the disk, is the main source of long term, and 27 day, variability. Variations in the distribution of brightness in quiet areas, perhaps from decay of active regions causing an enhanced network (``third component"), could also affect variability. While earlier models of the full disk variability have relied on proxy activity indicators, such as the Ca II plage area, a more direct indicator of activity may be full disk photospheric magnetograms. We have recast our earlier model (1980, J.G.R., 85, 2257) of ultraviolet variability to base it upon Kitt Peak full disk magnetograms, using the work of Cook and Ewing (1990, Ap. J., 355, 719) on the observed relationship of brightness at 1600 Angstroms with magnetic field strength. We compare our model results with observations of the solar irradiance from the SUSIM experiment flown on the UARS satellite. Title: The coronal context of transition region explosive events Authors: Moses, D.; Cook, J. W. Bibcode: 1994SSRv...70...81M Altcode: Transition region explosive events are observed throughout the quiet Sun and represent an interesting local heating phenomenon. The coronal counterparts of these events, if they exist, were not observed in a sounding rocket campaign dedicated to this objective. The coronal instrument complement on the SOHO spacecraft provides an opportunity to extend this search for the coronal counterparts of the transition region explosive events, as well as to explore the correspondence of explosive events with large scale coronal structures, such as with coronal dark lanes. Title: The Determination of Electron Densities in the Solar Atmosphere from the 1718.56 Angstrom /1486.51 Angstrom Emission-Line Ratio in N IV Authors: Keenan, F. P.; Harra, L. K.; Doschek, G. A.; Cook, J. W. Bibcode: 1994ApJ...432..806K Altcode: The theoretical electron density sensitive emission-line ratio R = I(1718.56 a)/I(1486.51 A) in N IV is presented for a range of Ne(approximately equals 1010 - 1012/cu cm) applicable to higher density solar plasmas, such as active regions. A comparison of these calculations with the observed values of R of several solar features obtained with the Naval Research Laboratory's S082B spectrograph on board Skylab reveals general agreement between theory and observation at pointings just above the limb, where line blends with N IV 1718.56 A should be insignificant, which provides experimental support for the accuracy of the line ratio calculations. Title: Solar Fine-Scale Structures in the Corona, Transition Region, and Lower Atmosphere Authors: Moses, Dan; Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Webb, D. F.; Davis, J. M.; Harvey, J. W.; Recely, F.; Martin, S. F.; Zirin, H. Bibcode: 1994ApJ...430..913M Altcode: The American Science and Engineering Soft X-ray Imaging Payload and the Naval Research Laboratory High Resolution Telescope and Spectrograph (HRTS) were launched from White Sands on 1987 December 11 in coordinated sounding rocket flights. The goal was to investigate the correspondence of fine-scale structures from different temperature regimes in the solar atmosphere, and particularly the relationship between X-ray bright points (XBPs) and transition region explosive events. We present results of the analysis of co-aligned X-ray images, maps of sites of transition region explosive events observed in C IV 105, HRTS 1600 A spectroheliograms of the Tmin region, and ground-based magnetogram and He I 10830 A images. We examined the relationship of He I 10830 A dark features and evolving magnetic features which correspond to XBPs. We note a frequent double ribbon pattern of the He I dark feature counterparts to XBPs. We discuss an analysis of the relationship of XBPs to evolving magnetic features by Webb et al., which shows that converging magnetic features of opposite polarity are the most significant magnetic field counterparts to XBPs. The magnetic bipolar features associated with XBPs appear as prominent network elements in chromospheric and transition region images. The features in C IV observations corresponding to XBP sites are in general bright, larger scale (approximately 10 arcsec) regions of complex velocity fields of order 40 km/s, which is typical of brighter C IV network elements. These C IV features do not reach the approximately 100 km/s velocities seen in the C IV explosive events. Also, there are many similar C IV bright network features without a corresponding XBP in the X-ray image. The transition region explosive events do not correspond directly to XBPs. The explosive events appear to be concentrated in the quiet Sun at the edges of strong network, or within weaker field strength network regions. We find a greater number of C IV events than expected from the results of a previous Spacelab 2 HRTS disk survey. We attribute this at least partly to better spatial resolution with the newer HRTS data. The full-disk X-ray image shows a pattern of dark lanes in quiet Sun areas. The number density of C IV events is twice as large inside as outside a dark lane (4.6 x 10-3 vs. 2.3 x 10-3 explosive events per arcsec 2). The dark lane corresponds to an old decaying magnetic neutral line. We suggest that this provides an increased opportunity for small-scale convergence and reconnection of opposite polarity magnetic field features, in analogy with the results of Webb et al. for XBPs but at a reduced scale of reconnection. Title: Coronal Electron Density Diagnostic from Fe XII Authors: Cook, J. W.; Keenan, F. P.; Harra, L. K.; Tayal, S. S. Bibcode: 1994ApJ...429..924C Altcode: We present observations of the forbidden coronal lines Fe XII 1242 A and 1349 A from active regions and from two flares, obtained by the SO82B slit spectrograph onboard Skylab. The line intensity ratio R = I(1242 A)/I(1349 A) is sensitive to electron density. We have calculated this ratio using recent atomic data, and obtained coronal electron densities at T = 1.5 x 106 K for our observations. We find a range in Ne of (0.5 to 7.2) x 109/cm-3 for active regions, which is in good agreement with previous results from other diagnostic ratios in this temperature range, and of approximately (0.9 to 12) x 109/cm-3 (or higher) for flares, which is generally low compared to previous flare results. The flare values employ particularly weak 1349 A observations and may not be reliable. From an observation of an active region just inside the solar limb, giving the best coverage in our data of both line profiles, we find a line width (FWHM) for both lines of 0.20 A, which corresponds to a nonthermal velocity of 18 km/sec. Title: The Allowed Lines of O IV near 1340 Angstrom in High Electron Density Solar Flares Authors: Cook, J. W.; Keenan, F. P.; Bhatia, A. K. Bibcode: 1994ApJ...425..861C Altcode: Intersystem lines of O IV near 1400 A have long been used as electron density diagnostics for solar plasmas at temperatures of around 160,000 K. In addition, however, several allowed lines of O IV near 1340 A should become visible in conditions of high plasma electron number density (greater than 1012/cu cm), such as during a solar flare. We present observations of the 1340 A and 1400 A regions of the solar spectrum for two solar flares, obtained by the SO82B spectrograph on board Skylab. We examine three candidate lines for allowed O IV in the flare spectra which occur at the correct wavelengths, but show that two of these are actually blends dominated by resonantly excited molecular lines of H2. The third candidate line, at 1343.51 A, we identify as the O IV allowd line. We present the density and temperature sensitivity of the ratio of allowed and intersystem O IV lines R = I(1343.51 A)/I(1407.39 A). The 1343.51 A line is clearly present in the first solar flare spectrum, and the ratio value implies an electron density of log Ne = 12.6. The second flare has a much weaker 1343.51 A profile, but again the ratio value implies a high electron density. Both these electron density values are in good agreement with estimates for each flare from independent diagnostic ratios. The simple presence alone of a clearly observed O IV 1343.51 A emission line implies an electron density greater than 1012/cu cm. Title: Magnetic Fields; Oscillations; and Heating in the Quiet Sun Temperature Minimum Region from Ultraviolet Observations at 1600 Angstroms Authors: Cook, J. W. Bibcode: 1994IAUS..154..287C Altcode: No abstract at ADS Title: The Allowed Lines of O IV Near 1340 Angstroms in High Electron Density Solar Flares Authors: Cook, J. W.; Keenan, F. P.; Bhatia, A. K. Bibcode: 1993AAS...183.6805C Altcode: 1993BAAS...25.1396C Intersystem lines of O IV near 1400 Angstroms have long been used as electron density diagnostics for solar plasmas at temperatures of around 160,000 K. In addition, however, several allowed lines of O IV near 1340 Angstroms should become visible in conditions of high plasma electron number density (Ne > 10(12) cm(-3) ), such as during a solar flare. We present observations of the 1340 Angstroms and 1400 Angstroms regions of the solar spectrum for two solar flares, obtained by the S082B spectrograph on board Skylab. We examine three candidate lines for allowed O IV in the flare spectra which occur at the correct wavelengths, but show that two of these are actually blends dominated by resonantly excited molecular lines of H2. The third candidate line, at 1343.51 Angstroms, we identify as the O IV allowed line. We present the density and temperature sensitivity of the ratio of allowed and intersystem O IV lines R = I(1343.51 Angstroms)/I(1407.39 Angstroms). The 1343.51 Angstroms line is clearly present in the first solar flare spectrum, and the ratio value implies an electron density of log Ne = 12.6. The second flare has a much weaker 1343.51 Angstroms profile, but again the ratio value implies a high electron density. Both these electron density values are in good agreement with estimates for each flare from independent diagnostic ratios. The simple presence alone of a clearly observed O IV 1343.51 Angstroms emission line implies an electron density greater than 10(12) cm(-3) . Title: Transition Region Explosive Events in an X-Ray Dark Lane Region of the Quiet Sun Authors: Cook, J. W.; Moses, D.; Brueckner, G. E.; Dere, K. P.; Bartoe, J. -D. F.; Webb, D.; Davis, J. M.; Harvey, J. W.; Recely, F.; Martin, S. F.; Zirin, H. Bibcode: 1993BAAS...25.1181C Altcode: No abstract at ADS Title: First Lunar Outpost support study Authors: Bartz, Christopher; Cook, John; Rusingizandekwe, Jean-Luc Bibcode: 1993STIN...9323054B Altcode: The First Lunar Outpost (FLO) is the first manned step in the accomplishment of the Space Exploration Initiative, the Vice President's directive to NASA on the 20th anniversary of the Apollo moon landing. FLO's broad objectives are the establishment of a permanent human presence on the moon, supporting the utilization of extraterrestrial resources in a long-term, sustained program. The primary objective is to emplace and validate the first elements of a man tended outpost on the lunar surface to provide the basis for: (1) establishing, maintaining and expanding human activities and influence across the surface; (2) establishing, maintaining and enhancing human safety and productivity; (3) accommodating space transportation operations to and from the surface; (4) accommodating production of scientific information; (5) exploiting in-situ resources. Secondary objectives are: (1) to conduct local, small scale science (including life science); (2) In-situ resource utilization (ISRU) demonstrations; (3) engineering and operations tests; (4) to characterize the local environment; and (5) to explore locally. The current work is part of ongoing research at the Sasakawa International Center for Space Architecture supporting NASA's First Lunar Outpost initiative. Research at SICSA supporting the First Lunar Outpost initiative has been funded through the Space Exploration Initiatives office at Johnson Space Center. The objectives of the current study are to further develop a module concept from an evaluation of volumetric and programmatic requirements, and pursue a high fidelity design of this concept, with the intention of providing a high fidelity design mockup to research planetary design issues and evaluate future design concepts. Title: Book reviews Authors: van Driel-Gesztelyi, L.; Meynet, G.; Gaizauskas, V.; Cook, J. W.; McKenna-Lawlor, S. M. P.; Garmany, C. D.; Jugaku, Jun; Lamers, Henny J. G. L. M.; Achterberg, A.; De Greve, J. P.; Dommanget, J.; van der Kruit, P. C. Bibcode: 1993SSRv...64..165V Altcode: No abstract at ADS Title: Book Review: Mechanisms of chromospheric and coronal heating / Springer, 1991 Authors: Cook, J. W. Bibcode: 1993SSRv...64..168C Altcode: 1993SSRv...64..168U No abstract at ADS Title: Solar O IV and S IV lines from the High Resolution Telescope and Spectrograph (HRTS) and the S082B spectrograph on board Skylab. Authors: Keenan, F. P.; Cook, J. W.; Doyle, J. G.; Dufton, P. L.; Hayes, M. A.; Kingston, A. E. Bibcode: 1993uxrs.conf..345K Altcode: 1993uxsa.conf..345K A comparison of theoretical O IV electron density diagnostics with observational data from a quiet solar region, a sunspot and an active region obtained with the High Resolution Telescope and Spectrograph (HRTS), and a flare observed with the S082B instrument on board Skylab, reveals that the O IV 1404.8 Å line is not only blended with the S IV 1404.8 Å transition, but also with an unknown feature that contributes a significant amount to the blend. It is therefore suggested that line ratios which include the O IV 1404.8 Å transition should not be employed as density diagnostics. Title: The Sun as a Star: High Spectral Resolution Solar Data Degraded to Low-Dispersion IUE Resolution Authors: Doyle, J. G.; Cook, J. W. Bibcode: 1992ApJ...391..393D Altcode: High spectral resolution (about 0.06 A) solar data for an active region and a large two-ribbon flare degraded to the typical resolution of low-dispersion (about 5 A) spectra of the IUE satellite are presented. This clearly shows the amount of detail yet to be acquired in stellar spectra and indicates the main spectral regions where line blending is a problem. Title: Solar SI II Line Ratios from the High-Resolution Telescope and Spectrograph Authors: Keenan, F. P.; Cook, J. W.; Dufton, P. L.; Kingston, A. E. Bibcode: 1992ApJ...387..726K Altcode: Theoretical emission-line ratios involving multiplets near 1262, 1306, and 1530 A are derived on the basis of new calculations of electron-impact excitation rates for allowed transition in Si II. A comparison of these line ratios with observational data from a quiet solar region, a sunspot, and an active region, obtained with the HIRTS on board a sounding rocket flight reveals that the 1530-A multiplet is optically thick, which is consistent with a calculation of the optical depth of these lines through a model atmosphere. The 1262- and 1306-A multiplets appear to be effectively optically thin. The average discrepancy between the theoretical and observed ratios is about 40 percent, which may not be significant, since the estimated uncertainties in both the calculated and experimental data are approximately 30 percent. Title: High Spectral Resolution Solar Data Degraded to Low Dispersion lUE Resolution Authors: Doyle, J. G.; Cook, J. W. Bibcode: 1992ASPC...26...49D Altcode: 1992csss....7...49D No abstract at ADS Title: Magnetic fields, oscillations, and heating in the quiet sun temperature minimum region Authors: Cook, John W. Bibcode: 1992AIPC..267...55C Altcode: 1992ecsa.work...55C The High Resolution Telescope and Spectrograph (HRTS) instrument contains a broadband spectroheliograph which has been tuned on sounding rocket flights to cover a passband centered on 1600 A˚, where the predominant flux contributor is continuum emission from the temperature minimum region (approximately 70% of the integrated intensity in quiet regions). I discuss the HRTS observations of the temperature minimum region in quiet areas and their relation with magnetic field, 5 minute oscillations, and heating. The brightness temperature of solar fine structure elements composing the supergranular network is found to be linearly proportional to the local absolute value of magnetic field strength. In cell centers, there is evidence for a 250 s period oscillation occurring in 10 arc sec scale patches, which, however, is energetically unimportant to the local heating budget. I discuss an interpretation in which a basal heating and 5 minute type oscillations occur globally, while the network bright points occur in magnetic regions, heated perhaps from partial dissipation of Alfven waves (whose energy flux is linearly proportional to B) in individual elemental 1500 G (at the photosphere) flux tubes which expand to form the temperature minimum fine structure bright points. Title: Magnetic fields, oscillations, and heating in the quiet sun temperature minimum region Authors: Cook, J. W. Bibcode: 1992ecsa..267...55C Altcode: No abstract at ADS Title: The chromospheric and transition region manifestations of an Ellerman bomb. Authors: Cook, J. W.; Brueckner, G. E.; Dere, K. P.; Martin, S. F.; Gayley, K. G. Bibcode: 1992BAAS...24.1074C Altcode: No abstract at ADS Title: The Sun as a Star: High Spectral Resolution Solar Data Degraded to Low Dispersion IUE Resolution Authors: Cook, J. W.; Doyle, J. G. Bibcode: 1991BAAS...23.1384C Altcode: No abstract at ADS Title: Comparision of Solar Flare Emission Measures from Broadband Soft X-Ray and Ultraviolet Spectrograph Observations Authors: Waljeski, K.; Cook, J. W.; Moses, D.; Brueckner, G. E. Bibcode: 1991BAAS...23.1468W Altcode: No abstract at ADS Title: Evidence for a 250 Second Brightness Oscillation at 1600 Angstrom in the Solar Temperature Minimum Region Authors: Cook, J. W.; Ewing, J. A. Bibcode: 1991ApJ...371..804C Altcode: A 330 s sequence of solar images at 1600 A, where the solar flux arises predominantly from the temperature minimum continuum, obtained from a sounding rocket flight, has been studied. The statistical distributions of the periods and amplitudes which result from fitting a sine wave to each individual 5 arcsec square box within a 350 x 350 arcsec quiet-sun field were obtained. Evidence is found for 250 s oscillations in the quiet-sun brightness temperature in about 10 arcsec coherent patches, with an average amplitude of 50 K. The amplitude corresponds to an energy flux of 180,000 ergs/sq cm/s for undamped, adiabatic, propagating sound waves, which is small compared to the heating requirement in the temperature minimum region. Title: Cell Center Bright Points as Dynamic Phenomena: Search for a Chromospheric Velocity Signature Authors: Cook, J. W. Bibcode: 1991BAAS...23.1028C Altcode: No abstract at ADS Title: The Prime Energy Release of a Solar Flare Authors: Brueckner, G. E.; Moses, D.; Cook, J. W.; Dere, K. P.; Korendyke, C. M.; Socker, D. G.; Bartoe, J. -D. F. Bibcode: 1991BAAS...23.1026B Altcode: No abstract at ADS Title: Flaring Active Region Structures in the Corona, Transition Region, and Lower Atmosphere Observed in the SAROC Authors: Moses, D.; Brueckner, G. E.; Cook, J. W.; Dere, K. P.; Korendyke, C. M.; Socker, D. G.; Bartoe, J. -D. F. Bibcode: 1991BAAS...23.1026M Altcode: No abstract at ADS Title: Fine structure of the solar transition region: observations and interpretation. Authors: Cook, J. W.; Brueckner, G. E. Bibcode: 1991sia..book..996C Altcode: The authors review recent observations of the solar transition region and the temperature minimum obtained with high spatial resolution, primarily ultraviolet spectra and spectroheliograms from sounding rocket and Spacelab 2 flights of the High Resolution Telescope and Spectrograph. Information on intensities, velocities, emission measures and electron densities can be determined. The authors discuss observational results and the implications of observed fine structure for our ideas of the structure and physics of the solar atmosphere. Inclusion of fine structure in our ideas about the transition region affects the plausibility of one-dimensional average models of the atmosphere, the determination of temperature gradients, possible mechanisms for nonradiative heating, and the comparison of transition region structures with corresponding high-resolution observations from the photosphere and corona. Title: High Spatial Resolution Observations of the Solar Transition Region: Spicules and Microflares (With 6 Figures) Authors: Cook, J. W. Bibcode: 1991mcch.conf...83C Altcode: No abstract at ADS Title: Relationship of Magnetic Field Strength and Brightness of Fine-Structure Elements in the Solar Temperature Minimum Region Authors: Cook, J. W.; Ewing, J. A. Bibcode: 1990ApJ...355..719C Altcode: A quantitative relationship was determined between magnetic field strength (or magnetic flux) from photospheric magnetograph observations and the brightness temperature of solar fine-structure elements observed at 1600 A, where the predominant flux source is continuum emission from the solar temperature minimum region. A Kitt Peak magnetogram and spectroheliograph observations at 1600 A taken during a sounding rocket flight of the High Resolution Telescope and Spectrograph from December 11, 1987 were used. The statistical distributions of brightness temperature in the quiet sun at 1600 A, and absolute value of magnetic field strength in the same area were determined from these observations. Using a technique which obtains the best-fit relationship of a given functional form between these two histogram distributions, a quantitative relationship was determined between absolute value of magnetic field strength B and brightness temperature which is essentially linear from 10 to 150 G. An interpretation is suggested, in which a basal heating occurs generally, while brighter elements are produced in magnetic regions with temperature enhancements proportional to B. Title: Coronal Dark Lanes and the Location of Transition Region Explosive Events Authors: Moses, D.; Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Davis, J. M. Bibcode: 1990BAAS...22..899M Altcode: No abstract at ADS Title: Return of the Hard Solar Flares' 154 Day Periodicity in Solar Cycle 22 and Evidence for a Phase Relationship of This Periodicity between Cycles 21 and 22 Authors: Brueckner, G. E.; Cook, J. W. Bibcode: 1990ApJ...350L..21B Altcode: No abstract at ADS Title: Heating by 300 s Waves in Nonmagnetic Areas of the Quiet Sun Temperature Minimum Authors: Cook, J. W.; Ewing, J. A. Bibcode: 1989BAAS...21.1180C Altcode: No abstract at ADS Title: Correspondence between solar fine-scale structures in the corona, transition region, and lower atmosphere from collaborative observations Authors: Moses, J. Daniel; Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Webb, D. F.; Davis, John M.; Recely, F.; Martin, S. F.; Zirin, H. Bibcode: 1989sxsr.reptR....M Altcode: The Soft X-Ray Imaging Payload and the High Resolution Telescope and Spectrograph (HRTS) instrument were launched from White Sands on 11 December 1987 in coordinated sounding rocket flights to investigate the correspondence of coronal and transition region structures, especially the relationship between X-ray bright points (XBPs) and transition region small spatial scale energetic events. The coaligned data from X-ray images are presented along with maps of sites of transition region energetic events observed in C IV (100,000 K), HRTS 1600 A spectroheliograms of the Tmin region and ground based magnetogram and He I 10830 A images. Title: Solar SI III Line Ratios from the High-Resolution Telescope and Spectrograph on Board Spacelab 2: The Effects of Non-Maxwellian Electron Distribution Function Authors: Keenan, F. P.; Cook, J. W.; Dufton, P. L.; Kingston, A. E. Bibcode: 1989ApJ...340.1135K Altcode: Electron impact excitation rates for transitions in Si III, incorporating the effects of non-Maxwellian electron velocity distribution functions (EVDFs), are presented for a range of electron temperatures appropriate to the solar transition region. A comparison of theoretical line ratios with observational data for a quiet solar region, a sunspot, and an active region obtained with the high-resolution telescope and spectrograph (HRTS) on board Spacelab 2 indicates that non-Maxwellian EVDFs may exist in the transition region. Non-Maxwellian effects appear to be larger for the sunspot than for the quiet sun, implying that the temperature gradient may be greater in the former. Title: Effect of Coronal Elemental Abundances on the Radiative Loss Function Authors: Cook, J. W.; Cheng, C. -C.; Jacobs, V. L.; Antiochos, S. K. Bibcode: 1989ApJ...338.1176C Altcode: The solar photosphere and corona abundances tabulated by Meyer (1985) and the chromospheric abundances given by Murphy (1985) are used here to recalculate radiative loss functions for equilibrium, low-density, optically thin plasmas. Results from a representative standard photospheric abundance set and from coronal and chromospheric abundance sets showing depletions of up to a factor of four in certain elemental abundances are compared. A significant difference is found for both the coronal and chromospheric abundance sets, with the peak of the radiative loss curve shifted closer to 10 to the 6th K than to the standard 2 x 10 to the 5th K found from photospheric abundances. Consequences of these new calculations, in particular for the cool loop model of Antiochos and Noci (1986), are discussed. Title: The HRTS Guest Investigator Program Authors: Lund, P.; Ewing, J.; Cook, J.; Dere, K.; Brueckner, G. Bibcode: 1989BAAS...21..841L Altcode: No abstract at ADS Title: Comparison of HRTS Sounding Rocket Observations at 1600 Å and Hα with Groundbased Magnetograms and He I 10830 Å Images Authors: Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P. Bibcode: 1989BAAS...21..840C Altcode: No abstract at ADS Title: Ultraviolet Observations of Macrospicules at the Solar Limb Authors: Dere, K. P.; Bartoe, J. -D. F.; Brueckner, G. E.; Cook, J. W.; Socker, D. G.; Ewing, J. W. Bibcode: 1989SoPh..119...55D Altcode: During the Spacelab 2 mission, the NRL High Resolution Telescope and Spectrograph (HRTS) obtained a time-series of broad-band ultraviolet images of macrospicules at the solar limb inside a polar coronal hole with a temporal resolution of 20 and 60 s. The properties of the macrospicules observed in the Spacelab data are measured and compared with the properties reported for EUV macrospicules observed during Skylab (Bohlin et al., 1975; Withbroe et al., 1976). There is a general agreement between the data sets but several differences. Because of the higher temporal resolution of the Spacelab data, it is possible to see macrospicules with shorter lifetimes than seen during Skylab, as well as variations on faster timescales. The largest (30-60') and fastest (150 km s -1) macrospicules seen during Skylab were not found in the Spacelab observations. The Spacelab data support the conclusion that many macrospicules decay by simply fading away. Title: Plasma Motions in an Emerging Flux Region Authors: Brueckner, G. E.; Bartoe, J. -D. F.; Cook, J. W.; Dere, K. P.; Socker, D.; Kurokawa, H.; McCabe, M. Bibcode: 1988ApJ...335..986B Altcode: Ultraviolet spectra of C IV show large nonthermal broadening in an area of emerging flux. These nonthermal motions are observed at a very early stage of reconnecting field lines. The spectra can be traced to small, rapidly changing surge or filament-like features which are seen in the center, blue, and red wing of H-alpha. They seem to have the characteristics of macrospicules or explosive events. They are precursors of the reconnection process. Plasma turbulence and/or plasma waves in the reconnecting plasma may cause the broad C IV line profiles. The activity in the transition zone precedes the formation of a bright chromospheric loop system. Title: Gas Flows in the Transition Region above Sunspots Authors: Kjeldseth-Moe, O.; Brynildsen, N.; Brekke, P.; Engvold, O.; Maltby, P.; Bartoe, J. -D. F.; Brueckner, G. E.; Cook, J. W.; Dere, K. P.; Socker, D. G. Bibcode: 1988ApJ...334.1066K Altcode: Strong downflows and moderate upflows in the transition region over a sunspot have been observed with the HRTS on Spacelab 2 in 1985. The flows are persistent in the sense that they are seen in the same spot for 5 days. The downflows are prominent in regions of limited extent (4arcsec - 6arcsec), and flow velocities are in the range 40 - 80 km s-1 and are thus supersonic. Upward flows have smaller velocities, 5 - 20 km s-1, but may extend over a larger area. In the downflowing regions there is always an appreciable amount of gas at rest in the line of sight. Flow speeds derived from the profiles of different lines formed in the transition region between 30,000 and 230,000K are very similar implying constant downflow in this temperature range. Title: Magnetic Field Strength and Brightness of Fine Structure Elements in the Solar Tmin Region Authors: Cook, J. W.; Ewing, J. A. Bibcode: 1988BAAS...20R.989C Altcode: No abstract at ADS Title: Determination of Film Characteristic Curves from Density Histograms Authors: Cook, J. W.; Ewing, J. A.; Sutton, C. S. Bibcode: 1988PASP..100..402C Altcode: A method for producing the film characteristic curve from exposures of the same image field with varying exposure times is developed, using the film density histogram distributions of the individual exposures. This method is appropriate for cases where a standard step wedge or other sensitometric calibration is not available, and where film reciprocity can be assumed for the exposure times used. The method is very general and incorporates as much of the film density information as the user desires. Title: The Correspondence Between Fine-Scale Structures in the Solar Corona and Transition Region Authors: Moses, J. D.; Bartoe, J. -D. F.; Brueckner, G. E.; Cook, J. W.; Dere, K. P.; Davis, J. M.; Webb, D. Bibcode: 1988BAAS...20..722M Altcode: No abstract at ADS Title: Correlation of Transition Region C IV High-Velocity Events With Magnetogram and He I 10830 Å Data Authors: Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Recely, F.; Martin, S.; Zirin, H. Bibcode: 1988BAAS...20..722C Altcode: No abstract at ADS Title: Results from the High Resolution Telescope and Spectrograph (HRTS) Experiment on Board Spacelab 2 Authors: Brueckner, G. E.; Bartoe, J. -D. F.; Cook, J. W.; Dere, K. P.; Socker, D. G. Bibcode: 1988ApL&C..27..151B Altcode: Several papers including reviews have been published during different stages of the data analysis after the SL-2 flight. In order to avoid repetition, this article lists all publications and briefly mentions some of the highlights. Title: Ultraviolet Observations of Solar Fine Structure Authors: Dere, Kenneth P.; Bartoe, John-David F.; Brueckner, Guenter E.; Cook, John W.; Socker, Dennis G. Bibcode: 1987Sci...238.1267D Altcode: The High Resolution Telescope and Spectrograph was flown on the Spacelab-2 shuttle mission to perform extended observations of the solar chromosphere and transition zone at high spatial and temporal resolution. Ultraviolet spectroheliograms show the temporal development of macrospicules at the solar limb. The C IV transition zone emission is produced in discrete emission elements that must be composed of exceedingly fine (less than 70 kilometers) subresolution structures. Title: Microscopic potentials for polarized triton elastic scattering Authors: Cook, J. Bibcode: 1987NuPhA.473..458C Altcode: The double folding model is used to calculate real central and spin-orbit potentials for triton elastic scattering. These potentials are used to fit cross sections and analysing powers at 17 MeV for targets ranging from 26Mg to 208Pb. For most targets the data are described as well as with phenomenological potentials. The real central potential can be used without any substantial renormalisation, but the spin-orbit potential needs to be increased in strength by a factor between 2 and 6. Comparisons are made with phenomenological studies of triton and 3He elastic scattering and with similar microscopic studies of 3He scattering. Title: Discrete Subresolution Structures in the Solar Transition Zone Authors: Dere, K. P.; Bartoe, J. -D. F.; Brueckner, G. E.; Cook, J. W.; Socker, D. G. Bibcode: 1987SoPh..114..223D Altcode: During operations on the Spacelab-2 Shuttle mission, the NRL High Resolution Telescope and Spectrograph (HRTS) recorded spectra of a variety of solar features in the 1200-1700 Å wavelength region which contains spectral lines and continua well suited for investigating the temperature minimum, the chromosphere and transition zone. These data show that, at the highest spatial resolution, the transition zone spectra are broken up from a continuous intensity distribution along the slit into discrete emission elements. The average dimensions of these discrete transition zone structures is 2400 km along the slit, but an analysis of their emission measures and densities shows that the dimensions of the actual emitting volume is conciderably less. If these structures are modelled as an ensemble of subresolution filaments, we find that these filaments have typical radii of from 3 to 30 km and that the cross-sectional fill factor is in the range from 10−5 to 10−2. The transport of mass and energy through these transition zone structures is reduced by this same factor of 10−5 to 10−2 which has significant consequences for our understanding of the dynamics of the solar atmosphere. Because the HRTS transition zone line profiles are not broadened by resolved large-spatial-scale solar velocity fields, the line widths of the CIV lines have been analyzed. The average line width is 0.195 Å (FWHM) and requires an average nonthermal velocity of 16 km s−1 (most-probable) or 19 km s−1 (root-mean-square) which is lower than previously observed values. Title: SKYLAB XUV Observations of Densities, Thermal Structure, and Mass Motions in a Compact Flare Authors: Widing, Kenneth G.; Cook, J. W. Bibcode: 1987ApJ...320..913W Altcode: The energetic limb flare of 1973 December 17 was one of the best Skylab examples of a class characterized by small volume, high energy density, and short lifetime. In the present paper the authors have studied the extensive series of slit spectra of this flare obtained with the NRL slit spectrograph on Skylab operating in the 1000 - 1945 Å range. An overview of the flare development and exposure chronology is given. Examples of the flare morphology observed in He II, Ne IV, and Mg VII are contrasted with the morphology observed in Fe XVII. Slit profiles of Fe XXI 1354 Å, O V 1371 Å, and Si IV 1403 Å are presented. The electron density is derived at selected phases from diagnostic line ratios of O IV, O V, S IV, and S V observed in the slit spectra. In the decay phase these densities are combined with the densities derived from high-temperature lines to obtain the density distribution in the flare between 105K and 6×106K. The arch structure within the 5arcsec×5arcsec kernel is resolved and an improved picture of the density spatial structure of the flare kernel is derived. Title: Effect on the Radiative Loss Function of Coronal Elemental Abundances Authors: Cook, J. W.; Cheng, C. -C.; Antiochos, S. K. Bibcode: 1987BAAS...19..931C Altcode: No abstract at ADS Title: Magnetic Reconnection in the Solar Transition Zone Authors: Brueckner, G. E.; Bartoe, J. -D. F.; Cook, J. W.; Dare, K. P.; Socker, D. G. Bibcode: 1987BAAS...19..942B Altcode: No abstract at ADS Title: SKYLAB XUV Observations of Densities and Thermal Structure in a Compact Flare Authors: Widing, K. G.; Cook, J. W. Bibcode: 1987BAAS...19Q.753W Altcode: No abstract at ADS Title: Transition Zone Flow Patterns in Sunspots Authors: Dere, K. P.; Bartoe, J. -D. F.; Brueckner, G. E.; Cook, J. W.; Socker, D. G. Bibcode: 1987BAAS...19..639D Altcode: No abstract at ADS Title: Statistical Properties of Small High-Velocity Events in the Solar Transition Region Authors: Cook, J. W.; Lund, P. A.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Socker, D. G. Bibcode: 1987LNP...291..150C Altcode: 1987csss....5..150C We discuss the energy contribution of small high-velocity events observed in the solar transition region to atmospheric heating. These events do not directly provide enough energy to heat the atmosphere, but are instead after-products of turbulent energy dissipation at the sites of the actual primary nonthermal heating process. Title: Observation of the Density Sensitive Line Mg V 1324 Å in a Solar Sunspot Authors: Cook, J. W.; Socker, D. G.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P. Bibcode: 1986BAAS...18R.991C Altcode: No abstract at ADS Title: Discrete Components of Solar Transition Zone Emission Authors: Dere, K. P.; Brueckner, G. E.; Bartoe, J. -D. F.; Cook, J. W.; Socker, D. G. Bibcode: 1986BAAS...18Q.662D Altcode: No abstract at ADS Title: Statistical Properties of Small High-Velocity Transition Region Events on the Sun Observed by HRTS on Spacelab 2 Authors: Cook, J. W.; Lund, P. A.; Brueckner, G. E.; Bartoe, J. -D. F.; Dere, K. P.; Socker, D. G. Bibcode: 1986BAAS...18..662C Altcode: No abstract at ADS Title: Results from the High Resolution Telescope and Spectrograph (HRTS) Experiment Authors: Brueckner, G. E.; Cook, J. W.; Dere, K. P. Bibcode: 1986BAAS...18..675B Altcode: No abstract at ADS Title: HRTS Spacelab 2 Observations of the Temporal Development of the C IV Transition Zone Authors: Dere, K. P.; Bartoe, J. -D. F.; Brueckner, G. E.; Cook, J. W.; Lund, P.; Socker, D. G. Bibcode: 1986BAAS...18..633D Altcode: No abstract at ADS Title: HRTS results from spacelab 2 Authors: Brueckner, G. E.; Bartoe, J. -D. F.; Cook, J. W.; Dere, K. P.; Socker, D. G. Bibcode: 1986AdSpR...6h.263B Altcode: 1986AdSpR...6..263B The HRTS instrument flew on the Spacelab 2 mission from 29 July - 6 August 1985. HRTS consisted of a 30 cm Gregorian telescope, a slit spectrograph covering the 1190-1680 Å region with 0.05 Å spectral resolution, a broadband (90 Å FWHM) spectroheliograph tuned to 1550 Å, and an H-alpha filter system. The spectrograph slit was 920 arc sec, approximately 1 R0, in length. Sub arc second spatial resolution along the slit is possible, but because of jitter in the Spacelab Instrument Pointing System (IPS) good exposures actually achieved 1-2 arc sec resolution. We describe the scientific results from HRTS. Title: Results from the NRL instruments on Spacelab 2 Authors: Bartoe, J. -D. F.; Brueckner, G. E.; Cook, J. W.; Dere, K. P.; Morrison, M. D. Bibcode: 1986aiaa.meetZ....B Altcode: The instrumental features of the high resolution Telescope and spectrograph (HRTS) and the solar UV spectral irradiance monitor (SUSIM) used for solar observations on the Spacelab 1 mission are described. The HRTS has three focal plane instruments receiving light from a 30 cm aperture furnishing at 15 X 15 arcmin FOV which can be modified for slit photography and raster scans. The focal plane instruments are a spectrograph, spectroheliograph and a television camera and photographic film fronted by a mica Fabry-Perot filter. About 13 hr of solar observations were made with the HRTS during the 8 day mission. Sample spectral and photographic data are provided and discussed. SUSIM is an UV spectrometer with redundant optical paths for in-flight calibration with a D2 lamp. It is sensitive in the 1200-4000 A range. Several wavelength ranges are evaluated. Particular attention is given to multitemporal Ly-alpha recordings. Title: HRTS Spacelab 2 Observations of Spicular Emission at the Solar Limb Authors: Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Socker, D. G. Bibcode: 1985BAAS...17..834C Altcode: No abstract at ADS Title: HRTS Results from SPACELAB2 Authors: Cook, J. W. Bibcode: 1985tphr.conf..308C Altcode: No abstract at ADS Title: Relative Contribution of Lines and Continus to Solar Far Ultraviolet Variability Authors: Cook, J. W.; Vanhoosier, M. E. Bibcode: 1985BAAS...17..630C Altcode: No abstract at ADS Title: HRTS results from Spacelab 2. Authors: Cook, J. W. Bibcode: 1985MPARp.212..308C Altcode: Three years from now it will be possible to look back on the Spacelab 2 flight and clearly pick out the most interesting new results obtained. Today the investigators are just beginning to examine the data, and can see a number of observations which seem exciting. A few representative examples are given. Title: HRTS observations of spicular emission at transition region temperatures above the solar limb Authors: Cook, J. W.; Brueckner, G. E.; Bartoe, J. -D. F.; Socker, D. G. Bibcode: 1984AdSpR...4h..59C Altcode: 1984AdSpR...4...59C Slit spectra and spectroheliograph observations were obtained during the fourth rocket flight of the High Resolution Telescope and Spectrograph (HRTS) on 7 March 1983. A curved slit 900 arc sec in length was placed at the solar limb on the western edge of the south polar coronal hole, giving both coronal hole and quiet region coverage. In addition, spectroheliograph images tuned to cover a passband around 1550 Å (primarily C IV at 105 K) were taken over an 8 × 15 arc min field. Simultaneous Hα images were obtained at Sac Peak Observatory. The C IV spectroheliograms show general spiked emission above the limb, and also several small loo- or prominence-like events. Slit spectra along the tops of several of these structures show tilted features which could be interpreted as rotational velocities of approximately 50 km s-1. Title: HRTS Evidence for Rotation of Transition Region Temperature Spicules Authors: Cook, J. W.; Brueckner, G. E.; Bartoe, J. -D. F.; Socker, D. G. Bibcode: 1984uxsa.coll...32C Altcode: 1984uxsa.conf...32C; 1984IAUCo..86...32C No abstract at ADS Title: Relative Contribution of Lines and Continua to Solar Far Ultraviolet Variability Authors: Cook, J. W.; Vanhoosier, M. E. Bibcode: 1983BAAS...15..951C Altcode: No abstract at ADS Title: Mass and energy balance in the 1973 August 9 flare Authors: Dere, K. P.; Cook, J. W. Bibcode: 1983A&A...124..181D Altcode: The mass and energy balance of the thermal plasma during the decay phase of the solar flare of August 9, 1973, are studied. The analysis is based on observationally determined values for the differential emission measure, density, turbulent and bulk velocities, and physical dimensions. The total particle content and total thermal energy content of the flare plasmas with temperatures above 100,000 K and their variation with time are calculated. The particle loss and the energy losses through radiation, conduction, and convection are evaluated. The decrease in total particle content can be accounted for by the convective losses through the loop footprints at 100,000 K. Radiation is the dominant energy loss mechanism although convective losses at 100,000 K can be important. Conductive losses at 100,000 K into cooler chromospheric material appear to be negligible. The decrease in the total energy content during the decay phase is equal to the sum of the energy losses over the period of observation. No requirement is found for continued heating during the decay phase. Title: High resolution telescope and spectrograph observations of solar fine structure in the 1600 A region Authors: Cook, J. W.; Brueckner, G. E.; Bartoe, J. -D. F. Bibcode: 1983ApJ...270L..89C Altcode: High spatial resolution spectroheliograms of the 1600 A region obtained during the HRTS rocket flight of 1978 February 13 are presented. The morphology, fine structure, and temporal behavior of emission bright points (BPs) in active and quiet regions are illustrated. In quiet regions, network elements persist as morphological units, although individual BPs may vary in intensity while usually lasting the flight duration. In cell centers, the BPs are highly variable on a 1 minute time scale. BPs in plages remain more constant in brightness over the observing sequence. BPs cover less than 4 percent of the quiet surface. The lifetime and degree of packing of BPs vary with the local strength of the magnetic field. Title: HRTS Observations of a Coronal Hole and Quiet Region at the Solar Limb Authors: Bartoe, J. -D. F.; Brueckner, G. E.; Cook, J. W.; Socker, D. G. Bibcode: 1983BAAS...15..703B Altcode: No abstract at ADS Title: Temporal Behavior of Quiet Sun Emission in the Tmin Region Authors: Cook, J. W.; Brueckner, G. E.; Bartoe, J. -D. F. Bibcode: 1982BAAS...14..938C Altcode: No abstract at ADS Title: Solar plages and the interpretation of stellar Ca II H and K line variations in late type dwarfs. Authors: Cook, J. W. Bibcode: 1982SAOSR.392A.181C Altcode: 1982csss....2..181C Approximately a dozen late type dwarf stars have been observed by Wilson (1978) to undergo cyclic variability in Ca II H and K line emission which seems analogous to the solar activity cycle. What might be learned about these stars from solar analogies? The Ca II K index is estimated variation of the Sun viewed as a star, and compared with the observed range of Wilson's stellar observations. Results indicate trends of increasing relative variation H-K(max)/H-K(min) with later spectral type, due to decreasing dilutional contribution of residual photospheric flux to a 1 A band at line center, and of increasing relative variation with decreasing relative time of rise to maximum tau rise/tau reminiscent of the observed solar correlation of a quick rise to sunspot maximum with a strong cycle. Title: Quiet Sun observations of the Al i autoionization lines λ1932 and λ1936 Authors: Cook, J. W.; Kjeldseth Moe, O. Bibcode: 1982SoPh...76..109C Altcode: We present quiet Sun observations obtained during a rocket flight of the Al I autoionization lines λ1932 and λ1936 at solar pointings ranging from μ = 0.73 out to the visible limb. Absolute intensities are estimated to be accurate to approximately ±20%. These lines progressively weaken with decreasing μ but never go into emission before finally disappearing with the continuum just beyond the visible solar limb. The observations are compared with LTE line profiles computed through the quiet Sun atmosphere of Vernazza et al. (1976). We discuss several areas of disagreement between the synthetic and observed profiles. Title: A high precision Solar Ultraviolet Spectral Irradiance Monitor for the wavelength region 120 400 nm Authors: Vanhoosier, M. E.; Bartoe, J. -D. F.; Brueckner, G. E.; Prinz, D. K.; Cook, J. W. Bibcode: 1981SoPh...74..521V Altcode: There exists a growing need to improve the accuracy of measurement of the absolute solar flux within the wavelength range 120-400 nm. Although full-disk solar fluxes and variations thereof in the 120-400 nm region are required to model the solar atmosphere, current increased interest in the measurements arises from their importance in modeling the terrestrial atmosphere. We describe the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) experiment under development at the Naval Research Laboratory (NRL) for flight aboard the Space Shuttle and the Upper Atmospheric Research Satellite (UARS). SUSIM will monitor the solar flux in the 120-400 nm region with high precision, using an in-flight calibration system to reduce absolute error to < 10%, and error relative to the 400 nm continuum to < 1%. Title: Folding model analysis of triton and 3He elastic scattering Authors: Cook, J.; Griffiths, R. J. Bibcode: 1981NuPhA.366...27C Altcode: A double folding model using the M3Y interaction has been successfully applied to a wide range of triton and 3He data. A projectile energy and mass dependence in the exchange potential proportional to E/Ap is shown to be adequate between 11 and 27 MeV/nucleon. Normalization factors for triton and 3He real potentials of ~ 0.6 and ~ 0.8, respectively, are in accordance with those of other light projectiles subject to break-up. Title: Latitudinal anisotropy of the solar far ultraviolet flux - Effect on the Lyman alpha sky background Authors: Cook, J. W.; Meier, R. R.; Brueckner, G. E.; van Hoosier, M. E. Bibcode: 1981A&A....97..394C Altcode: An estimate is given for the anisotropy of the solar full disk flux in the far ultraviolet, as it would be observed for lines of sight within and above the ecliptic plane through the predominant influence of plages at low heliocentric latitudes. The flux anisotropy for Lyman alpha, at a level of solar activity with a sunspot number of roughly 160, is approximately 0.88 for the integrated flux over the Lyman alpha profile and 0.83 for the flux at line center. The effect of this Lyman alpha flux anisotropy on the Lyman alpha sky background intensity, resonantly backscattered from the local interstellar medium that is streaming through the solar system, is examined. It is concluded that the solar Lyman alpha anisotropy should be included in models of the interplanetary background during periods of moderate to high solar activity. Title: Solar Ca II H and K Line Variations: The Sun as a Star Authors: Cook, J. W. Bibcode: 1981BAAS...13..877C Altcode: No abstract at ADS Title: Mass and Energy Balance in the 1973 August 9 Flare Authors: Cook, J. W.; Dere, K. P. Bibcode: 1981BAAS...13..554C Altcode: No abstract at ADS Title: 6.7Li Optical-Model Parameters Authors: Cook, J. Bibcode: 1981ADNDT..26...19C Altcode: A compilation is presented of optical-model parameters obtained from an extensive survey of the literature from 1968 to 1981 on the elastic-scattering cross-section distributions of 6,7Li. Title: Comment on 'Variability of the far-infrared solar temperature minimum with the solar cycle' Authors: Cook, J. W.; Brueckner, G. E.; Vanhoosier, M. E. Bibcode: 1980A&A....92L...7C Altcode: We compare the solar cycle variation of the full disk brightness temperature minimum in the far-infrared reported by Müller et al. (1980) to the variation found in the far-ultraviolet Tmin continuum. The far-ultraviolet observations suggest that the far-infrared variability should be nearer 9,-60 K than the value of 200 K reported by Müller et al. (1980), whose solar cycle variation is comparable to their measurement error. Title: HRTS Observations of Solar Fine Structure in the Tmin Region Authors: Cook, J. W.; Brueckner, G. E.; Bartoe, J. -D. F. Bibcode: 1980BAAS...12..916C Altcode: No abstract at ADS Title: A useful function-fitting programme Authors: Cook, J. Bibcode: 1980Obs...100...79C Altcode: No abstract at ADS Title: Variability of the solar flux in the far ultraviolet 1175-2100 Å Authors: Cook, J. W.; Brueckner, G. E.; Vanhoosier, M. E. Bibcode: 1980JGR....85.2257C Altcode: We examine the expected range of variability over the solar cycle of the far UV flux (irradiance) in selected lines and continua within the wavelength range 1175-2100 Å which results from a simple two-component model of the full-disk flux. We determine contrast factors I(plage)/I(quiet region) for various lines and continua and estimate the fraction of the disk that is covered by plages at various times in the solar 11-year cycle. We assume (1) that enhanced far UV emission arises from the same plage areas visible in Ca II emission, (2) that our contrast values are typical, and (3) that both the plage and quiet region intensities per unit surface area remain constant over the solar cycle, so that flux variability is caused only by a greater or lesser fraction of surface area covered by plages. We discussed available observational evidence for these assumptions. Our results are in good agreement with the Lα fluxes published by Vidal-Madjar [1975] and the recent broadband observations by Hinteregger (private communication, 1979), but they are in disagreement with the flux variability reported by Health and Thekaekara [1977] over the 1700-3000-Å range. Title: Latitudinal Anisotropy of the Solar Far Ultraviolet Flux: Effect on the Lα Sky Background Authors: Cook, J. W.; Meier, R. R.; Brueckner, G. E.; Vanhoosier, M. E. Bibcode: 1980BAAS...12..544C Altcode: No abstract at ADS Title: Solar Plages and the Interpretation of Stellar Ca II H and K Line Variations in Late Type Dwarfs Authors: Cook, J. W. Bibcode: 1980BAAS...12..520C Altcode: No abstract at ADS Title: The chromosphere and transition region Authors: Canfield, R. C.; Brown, J. C.; Craig, I. J. D.; Brueckner, G. E.; Cook, J. W.; Doschek, G. A.; Emslie, A. G.; Machado, M. E.; Henoux, J. -C.; Lites, B. W. Bibcode: 1980sfsl.work..231C Altcode: 1980sofl.symp..231C The physical processes occurring as a result of the transfer of energy and momentum from the primary solar flare energy release site in the corona to the underlying chromosphere and transition region during the course of the flare are investigated through a comparison of theoretical models and observational data. Static, dynamic and hydrodynamic models of the lower-temperature chromospheric flare are reviewed. The roles of thermal conduction, radiation, fast particles and mass motion in chromosphere-corona interactions are analyzed on the basis of Skylab UV, EUV and X-ray data, and empirical and synthetic models of the chromospheric and upper photospheric responses to flares are developed. The canonical model of chromospheric heating during flares as a result of primary energy release elsewhere is found to be justified in the chromosphere as a whole, although not entirely as the temperature minimum, and a simplified model of horizontal chromospheric flare structure based on results obtained is presented. Title: Mass Flow and Energy Balance in a Solar Flare Authors: Cook, J. W.; Dere, K. P. Bibcode: 1979BAAS...11..678C Altcode: No abstract at ADS Title: Skylab observations of the Al I autoionization lines lambda 1932 and lambda 1936 during a solar flare. Authors: Cook, J. W. Bibcode: 1979ApJ...234..378C Altcode: Observations are presented of the Al I autoionization lines gamma 1932 and gamma 1936 during the H alpha class SN subflare of 1973 August 9, obtained from the NRL slit spectrograph aboard Skylab. These profiles are compared with observations from an active-region plage and with the quiet-sun observations of McAllister. Line profiles through model flare and quiet-sun atmospheres are computed assuming local thermodynamic equilibrium. The Al I autoionization lines are sensitive to the conditions just below the temperature-minimum region of the model atmosphere, and the observations support evidence that increased heating of this region occurs during flares. It shown, using observations from three additional flares, that excess flare heating down to the Tmin region probably occurs only near loop footpoints. The behavior of Fe and Fe II lines in the 1920 A range is also discussed. Title: Solar C III line intensity ratios observed from Skylab. Authors: Cook, J. W.; Nicolas, K. R. Bibcode: 1979ApJ...229.1163C Altcode: Solar observations of C III line intensity ratios are analyzed which were obtained by the Naval Research Laboratory extreme-ultraviolet slit spectrograph on Skylab from quiet and active regions, coronal holes, prominences, and a flare. Electron densities are determined by comparing the observed intensity ratios to their theoretical variation as a function of electron density and temperature. Both isothermal line ratios that are evaluated at a characteristic emitting temperature and ratios that are integrated through the temperature and density structure of a model solar atmosphere are calculated. The density-sensitive ratios R(Si IV 1402/C III 1908) and R(Si III 1892/C III 1908) are also used to derive additional values of electron density. It is found that the ratios R(C III 1247/C III 1908), R(Si IV 1402/C III 1908), and R(Si III 1892/C III 1908) give consistent values of electron density for each feature. The C III 1908-A, Si III 1892-A, and Si IV 1402-A lines have recently been observed from the IUE satellite in spectra of late-type stars, and can serve as practical density diagnostics that are independent of assumptions about the stellar surface gravity. Title: The decay of the 1973 August 9 flare. Authors: Dere, K. P.; Cook, J. W. Bibcode: 1979ApJ...229..772D Altcode: The state and evolution of the decay-phase plasma from a compact solar flare that occurred on August 9, 1973, are investigated on the basis of XUV and X-ray observations from Skylab and Solrad 9. Density-sensitive line ratios are used to determine the electron density over the temperature range from 30,000 to 5 million K, and the differential emission measure in the temperature interval from 30,000 to 20 million K is derived for several times in the decay phase. The morphology of the flare is discussed, including its relation to the observed photospheric magnetic field. The sequential formation of new loops during the decay phase is emphasized as an essential element for understanding the decay phase of the flare. This idea is developed further by comparing the observed differential emission measure with that predicted by a semiempirical model which considers the sequential formation of isothermal loops that cool by radiation and thermal conduction. Title: EUV observations of quiescent prominences from Skylab. Authors: Moe, O. K.; Cook, J. W.; Mango, S. A. Bibcode: 1979SoPh...61..319M Altcode: We report measurements of line intensities and line widths for three quiescent prominences observed with the Naval Research Laboratory slit spectrograph on ATM/Skylab. The wavelengths of the observed lines cover the range 1175 Å to 1960 Å. The measured intensities have been calibrated to within approximately a factor 2 and are average intensities over a 2 arc sec by 60 arc sec slit. We derive nonthermal velocities from the measured line widths. The nonthermal velocity is found to increase with temperature in the prominence transition zone. Electron densities and pressures are derived from density sensitive line ratios. Electron pressures for two of the prominences are found to lie in the range 0.04-0.08 dyn cm−2, while values for the third and most intense and active of the three prominences are in the range 0.07-0.22 dyn cm−2. Title: A semiempirical model of the upper flare chromosphere. Authors: Lites, B. W.; Cook, J. W. Bibcode: 1979ApJ...228..598L Altcode: Ultraviolet spectra of the August 9, 1973, flare taken with the NRL S082B spectrograph aboard ATM/Skylab have been analyzed to derive a semiempirical model of the flare chromosphere between 5500 and 100,000 K. The hydrogen radiative transfer is solved to obtain a self-consistent set of physical conditions within the flare atmosphere, from which line profiles and continua of the ions C I, C II, C III, and C IV are synthesized and compared with the observations. The model exhibits a rapid rise in the temperature at a column mass of 0.0003 g/sq cm. There is some evidence for much of the C III line emission's arising from flare kernels not exceeding 3 arcsec in size, and the C IV line profiles indicate the possibility of nonequilibrium excitation. Title: The Variability of the Solar Ultraviolet Radiation in the Wavelength Region 1200-2100 Å Authors: Vanhoosier, M. E.; Cook, J.; Brueckner, G. E. Bibcode: 1979BAAS...11..421V Altcode: No abstract at ADS Title: Skylab Observations of the A1 I Autoionization Lines λ 1932 and λ 1936 During a Solar Flare Authors: Cook, J. W. Bibcode: 1979BAAS...11Q.439C Altcode: No abstract at ADS Title: EUV continua of solar flares 1420 - 1960 Å. Authors: Cook, J. W.; Brueckner, G. E. Bibcode: 1979ApJ...227..645C Altcode: Measurements of absolute continuum intensities in the wavelength range 1420-1960 A are presented for the SN subflare of 1973 August 9 and the 2B flare of 1973 September 7, observed from the NRL spectrograph aboard Skylab. Continuum measurements are also given for two active-region plages, which are used for background nonflaring levels. Major enhancement of the flare continuum intensity above the plage backgrounds occurs in the Si I 3P and 1D continua. The observed brightness-temperature minimum of the plages is approximately 310 K above the quiet-sun minimum, and occurs at longer wavelength. The earliest flare brightness-temperature minima are approximately 200 K above the plage minimum, and also at longer wavelength. The observed decay time of the flare brightness temperature, which is comparable to the Solrad 9 X-ray decay time, is much longer than the Ulmschneider radiative relaxation time for the 1973 September 7 flare and marginally longer for the 1973 August 9 flare, suggesting continuous excess heating of the plage temperature minimum region throughout the period of our flare observations. Title: ATM evidence for a nonthermal proton/electron energy flux ratio in solar flares. Authors: Canfield, R. C.; Cook, J. W. Bibcode: 1978ApJ...225..650C Altcode: An observational search has been carried out for asymmetry in the wings of L-alpha during flares, produced by beams of nonthermal protons injected into the chromosphere from the corona as suggested by Orrall and Zirker (1976). The data base is the ATM/Skylab EUV spectrograms from the NRL S082B spectrograph. The asymmetries expected to be present in the normal thermal profile are discussed, and detailed consideration is given to the flare that occurred at 1551 UT on August 9, 1973, which was observed during the nonthermal phase. In this flare only very small L-alpha asymmetries are observed, not large enough to be statistically significant. It is shown that this result, combined with microwave radio data for information on nonthermal electrons, implies that the energy flux of nonthermal protons injected into the chromosphere at energies above 20 keV is less than approximately 0.02 times that of electrons of the same energy range in the observed events. Title: ATM Evidence for a Low Non-Thermal Proton/Electron Energy Flux Ratio in Solar Flares. Authors: Canfield, R. C.; Cook, J. W. Bibcode: 1978BAAS...10..441C Altcode: No abstract at ADS Title: Solar C III Line Ratios Observed from Skylab. Authors: Cook, J. W.; Nicolas, K. R. Bibcode: 1978BAAS...10R.439C Altcode: No abstract at ADS Title: Spectrophotometry of HDE 226868 (Cygnus X-1) Authors: Cook, John William Bibcode: 1978shc..book.....C Altcode: No abstract at ADS Title: Spectrophotometry of HDE 226868 (Cygnus X-1) Authors: Cook, John William Bibcode: 1977PhDT.......244C Altcode: No abstract at ADS Title: Spectrophotometry of HDE 226868 Authors: Cook, J. W. Bibcode: 1977PhDT.........1C Altcode: Spectra of HDE 226868, the optical counterpart of the X-ray source Cygnus X-1, were obtained at a dispersion of approximately 84 A/mm. Plates were scanned on a microdensitometer and the resulting density measurements converted to relative intensities using standard photometric calibration methods. The resulting spectra, representing a region from redward of H alpha to blueward of H delta, were reduced to rectified spectra in continuum units. Selected lines were examined, and the line profiles and equivalent widths obtained. The equivalent widths of hydrogen and helium absorption lines appear consistent with a normal 09.7 Iab star. Parameters of the Cygnus X-1 system are calculated and a qualitative model for the optical behavior examined. The difficulties in determining electron temperature and density in the region of optical emission are discussed. Title: Hughes's Induction Balance Authors: Cook, J. Bibcode: 1887Natur..36R.605C Altcode: HAVING just made a Hughes's induction balance, I have, in the course of some experiments with it, observed what was new to me, for I have not seen it mentioned in any account of the balance. I take the liberty, therefore, of asking through your columns whether the explanation resolves itself into the difference between paramagnetic and diamagnetic substances. The apertures of my bobbins are 1½ inch in diameter; my primary current is from three Daniell's, and the break is a bent steel spring whose free point just grazes the surface of a mercury cup, so that the merest touch with a finger causes a series of regular breaks. Now, if I place an iron or steel disk, or ring, such as a key-ring, inside the aperture, the telephone sounds loudly if the plane of the disk or ring is at right angles to the plane of the coils; but very very faintly if it is parallel to the plane of the coils. On the other hand, if a disk, or ring, or coil of wire, of any of the diamagnetic metals-copper, brass, zinc, silver, gold, aluminium, lead-be used, the telephone sounds loudly if the plane of the disk or ring he parallel to the plane of the coils; but very faintly, if at all, when it is perpendicular to the plane of the coils. Further, if a short bar of soft iron, or of nickel, be inserted so that the length of the bar is parallel to the plane of the coils, almost no sound is heard; but if it be turned through a right angle so as to be perpendicular to the plane of the coils, the sound is a maximum. Have we in this simple instrument the ready means of distinguishing paramagnetic from diamagnetic substances? Title: An Account of the Flowing of the Tides in the South Sea, as Observed on Board His Majesty's Bark the Endeavour, by Lieut. J. Cook, Commander, in a Letter to Nevil Maskelyne, Astronomer Royal, and F. R. S. Authors: Cook, J. Bibcode: 1772RSPT...62..357C Altcode: No abstract at ADS