pierce

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Author name code: pierce
ADS astronomy entries on 2022-09-14
=author:"Pierce, A. Keith" OR =author:"Pierce, A.K."

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Title: Wavelength Shifts in the Solar Photospheric Spectrum
Authors: Pierce, A. Keith; Lopresto, James C.
2000SoPh..196...41P Altcode:
Wavelength shifts converted to velocities between solar lines observed
at disc center and laboratory wavelengths of Fe i, Fe ii, Ti i, Ni i,
and Fe i lines in the near infrared are plotted as a function of the
logarithm of their solar equivalent width in milliångstroms. The
need for wavelengths based on the wavelength standards is stressed. A
comparison of photographic Fe i solar wavelength is shown to agree,
on the average, with Fourier Transform Spectrometer solar wavelengths
within less than 0.5 milliångstroms. Using Balthasar's limb effect
tables we convert the disc center velocities to limb velocities and
find, though the scatter is large, that there is little evidence for
a super-gravitational red shift.

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Title: Observations of the limb effect in potassium λ7699
Authors: Lopresto, J. C.; Kraus, Pauline M.; Pierce, A. K.
1994SoPh..149..243L Altcode:
Center-to-limb observations of the KI λ7699 line made on 30 days over
a five-year period using the McMath-Pierce Solar Telescope at Kitt
Peak are presented. Both a relative and absolute limb effect have
been derived from the data. Our determination of the limb effect in
KI λ7699 shows a linear increase to the limb amounting to about 40
m s−1.

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Title: The Observed Limb Effect in Fraunhofer Lines - Part Two
Authors: Pierce, A. K.
1992SoPh..139....1P Altcode:
In this paper the absolute limb effect for a number of Fraunhofer
lines observed at the McMath Solar Observatory is given. Results,
uncorrected for scattered light, are given for the following lines:
FeIλ37334.9, λ3735.3, λ5123.7, λ5250.2, λ5434.5, λ6678.0,
and λ8886.6. Additional lines observed are five lines of CN
λλ3876.3-3880.0, two lines of CaIλ6161.3 and λ6162.2, one line of
NaI, λ6160.7, and one CN line (λ7957.0) of the red system.

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Title: Solar Gravitational Redshift from the Infrared Oxygen Triplet
Authors: Lopresto, James C.; Schrader, Charles; Pierce, A. K.
1991ApJ...376..757L Altcode:
The difference in wavelength between the IR oxygen triplet 7772-7775
A in the sun and in the laboratory has been observed. Converted
to velocities, the disk values, extrapolated to the limb, give a
redshift of 655 m/s compared to the value of 636 m/s predicted from
the principal of equivalence. Observations of the chromospheric oxygen
lines in emission just off the sun's limb give a velocity of 627 m/s
or 0.99 of the Einstein prediction.

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Title: The Observed Limb Effect in Fraunhofer Lines - Part One
Authors: Pierce, A. K.
1991SoPh..133..215P Altcode:
The absolute limb effect is presented for FeI lines λ 3767 and λ3969;
for five TiI lines of multiplet 42 near λ 4535 and one TiII line at
λ 4534; two lines of MgI, λ 4571 and λ 5172; two lines of BaII at
λ 5854 and λ 6497. The scattered light of the McMath solar telescope
is illustrated by several figures but not applied to the limb-effect
observations. It is suggested that the supergravity shift at the limb
is the result of scattering of the atoms in anisotropic velocity field.

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Title: The Solar Gravitational Red Shift
Authors: Lopresto, J. C.; Pierce, A. K.
1989BAAS...21..752L Altcode:
No abstract at ADS

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Title: A Windscreen around the Heliostat of the Mcmath Solar Telescope
Authors: Pierce, A. Keith
1987SoPh..107..397P Altcode:
No abstract at ADS

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Title: Solar Meridional Flow
Authors: Pierce, A. Keith; Lopresto, James C.
1987BAAS...19..935P Altcode:
No abstract at ADS

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Title: Solar Gravitational Red Shifts of 07772A and K7699A
Authors: Lopresto, James C.; Pierce, A. Keith
1987BAAS...19..942L Altcode:
No abstract at ADS

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Title: The Morphology of Solar Granulations and Dark Networks
Authors: Graves, J. Elon; Pierce, A. Keith
1986SoPh..106..249G Altcode:
Solar granules are classified into four groups according to their
shapes and splitting by sharp rifts crossing them. The appearance and
evolution of `white-light dark networks' is described.

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Title: The center-to-limb wavelength shift of a number of Fraunhofer
lines
Authors: Lopresto, J. C.; Pierce, A. K.
1985SoPh..102...21L Altcode:
The center-to-limb wavelength shifts of the cores of faint, medium and
strong Fraunhofer lines are presented: FeI 3767, CaII 3968, CeII 4222,
CaI 4227, NaI 5896, BaII 6497, and KI 7699.

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Title: Center to Limb Behavior of Some Strong and Medium Strong
Fraunhoffer Lines
Authors: Lopresto, J. C.; Pierce, A. K.
1985BAAS...17R.756L Altcode:
No abstract at ADS

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Title: Investigation of Photospheric Limb-Darkening Variation Between
1980 and 1985
Authors: Petro, L. D.; Foukal, P. V.; Rosen, W. A.; Pierce, A. K.;
Kurucz, R. L.
1985BAAS...17..644P Altcode:
No abstract at ADS

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Title: Center to Limb Behavior of Some Strong Fraunhofer Lines
Authors: Lopresto, J. C.; Pierce, A. K.
1984BAAS...16.1001L Altcode:
No abstract at ADS

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Title: A study of solar photospheric limb-darkening variations
Authors: Petro, L. D.; Foukal, P. V.; Rosen, W. A.; Kurucz, R. L.;
Pierce, A. K.
1984ApJ...283..426P Altcode:
The authors have obtained regular observations of photospheric limb
darkening, using the McMath Solar Telescope, to study possible slow
changes in the global temperature structure, in Teff, and in
the ultraviolet continuum flux from the quiet Sun. This paper reports
on the analysis of data obtained on 15 days between 1980 September and
1982 December in a continuum window at λ4451. There are no variations
of global limb darkening exceeding 0.1% at the 99% confidence level. The
implications of these measurements for slow changes in solar luminosity,
convection zone structure, and ultraviolet flux are discussed.

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Title: Solar Rotation from a Number of Fraunhofer Lines
Authors: Pierce, A. K.; Lopresto, J. C.
1984SoPh...93..155P Altcode:
Solar differential rotation for 1982-83 obtained at the double pass
spectrograph of the McMath telescope at Kitt Peak, are presented
for lines of Fe, Mg, Na, K, Si, and O in the wavelength interval
λλ3820-10827. The results are analyzed by representations in Legendre
polynominals and a power series. The differential rotation is very close
to the result obtained by Howard and Harvey in 1966-68 at Mt. Wilson
but with a slightly greater amplititude. We find a mean equatorial
rate of rotation of 1.977 km s-1. Day to day variations are
observed in the equatorial zone; a stable rate of rotation is observed
outside of the sunspot zone.

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Title: Solar Rotation From a Number of Fraunhofer Lines
Authors: Lopresto, J. C.; Pierce, A. K.
1984BAAS...16..532L Altcode:
No abstract at ADS

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Title: Fraunhofer Line Profiles
Authors: Pierce, A. Keith
1984SoPh...90..195P Altcode:
It is shown that comparing an observed Fraunhofer profile to a fitted
gaussian yields more information on shape and asymmetry of the solar
line than the simple bisector method.

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Title: Variation of Solar Limb Darkening
Authors: Petro, L. D.; Foukal, P. V.; Rosen, W. A.; Kurucz, R. L.;
Pierce, A. K.
1983BAAS...15..951P Altcode:
No abstract at ADS

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Title: Variations in photospheric limb darkening as a diagnostic of
changes in solar luminosity
Authors: Rosen, W. A.; Foukal, P. V.; Kurucz, R. L.; Pierce, A. K.
1982ApJ...253L..89R Altcode:
The paper reports on photospheric limb-darkening measurements
obtained with the McMath Solar Telescope in July, September, and
October 1980 as part of a continuing program to investigate possible
long-term variations in the photospheric emergent flux. A total of
243 usable full-diameter scans were recorded over seven days in the
clean continuum window at 4451-25 A. The limb darkening was found to
decrease significantly between September 25 and 26. It is suggested
that this decrease was caused by a decrease of the temperature gradient
in the upper photosphere in the region above approximately tau(5000) =
0.5. The small increase in effective temperature that might accompany
this limb-darkening variation is estimated using a standard radiative
equilibrium photospheric model.

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Title: Center to limb observations of sodium lines in the solar
spectrum
Authors: Pierce, A. K.; Slaughter, C.
1982ApJS...48...73P Altcode:
Center to limb (cos theta = 1.0 to 0.1) intensities are given for the
profiles of 25 sodium lines distributed at wavelengths from 3302 to
22083 A in the solar spectrum. Central intensities and half-widths
are tabulated for five additional sodium lines.

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Title: Photospheric Limb Darkening as a Ground-based Diagnostic for
Variations in the Solar Effective Temperature
Authors: Rosen, W. A.; Foukal, P. V.; Kurucz, R.; Pierce, A. K.
1981BAAS...13..551R Altcode:
No abstract at ADS

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Title: Solar limb darkening in the interval 7404 - 24018 Å, II.
Authors: Pierce, A. K.; Slaughter, C. D.; Weinberger, D.
1977SoPh...52..179P Altcode:
The coefficients of third degree and fifth degree polynomial
representations of limb darkening are tabulated for 50 wavelengths in
the interval λλ 7404-24 018.

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Title: Solar limb darkening. I: lambda lambda (3033 - 7297).
Authors: Pierce, A. K.; Slaughter, C. D.
1977SoPh...51...25P Altcode:
The coefficients of several polynomial representations of the limb
darkening at 62 wavelengths in the UV and visible portions of the
solar spectrum obtained at the McMath Solar Telescope are presented
in tabular form. Full corrections for scattered light and seeing have
been included in the reductions.

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Title: The Solar Spectrum Between .3 and 10 μm
Authors: Pierce, A. K.; Allen, R. G.
1977soiv.conf..169P Altcode:
No abstract at ADS

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Title: Kitt Peak 60-cm vacuum telescope
Authors: Livingston, W. C.; Harvey, J.; Pierce, A. K.; Schrage, D.;
Gillespie, B.; Simmons, J.; Slaughter, C.
1976ApOpt..15...33L Altcode:
A major new solar-research telescope conceived and built during a
time of budget restraint is described. The observation of magnetic
and velocity (circulation) field structure on a synoptic basis and
with diffraction-limited resolution is the aim. New optical features
include the use of oversize mirrors and windows to avoid thermal
edge effects and the placement of the coelostat feed outside the
vacuum, mainly for economy. The site selected has prevailing winds
that clear thermals from these mirrors. Test data in the form of
the system MTF and optical transmission, together with examples of
full disk magnetograms and photoheliograms, show present performance
capability. Measured MTF indicates a response of 0.2 at 1 sec of arc
(whereas diffraction-limited response would be about 0.8). System
transmission, including the accompanying spectrograph, is only 2-3%
(wavelength 0.44-1.1 microns). Thus, both the optical quality and
efficiency are subject to improvement.

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Title: The Kitt Peak 60-cm Vacuum Telescope
Authors: Pierce, A. K.; Livingston, W. C.; Harvey, J. W.; Schrage,
D.; Gillespie, B.; Simmons, J.; Slaughter, C.
1976ApOpt..15...33P Altcode:
No abstract at ADS

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Title: Thorium Comparison Spectrum
Authors: Breckinridge, James B.; Pierce, A. Keith; Stoll, Clifford P.
1975ApJS...29...97B Altcode:
Wavelengths for approximately 1850 thorium emission lines between
2720 and 8805 A are given. The accuracy of these measures appears to
be better than ::i:: 0.001 A. These measures, made from photographic
plates taken with the 13 .7-m focal length grating spectrograph at
the McMath Solar Telescope at Kitt Peak, are part of work done for
the solar wavelength atlas program (Pierce and Breckirridge, Kitt Peak
Contributions 559, 1973). We suggest they be used for general stellar
and solar comparison wavelengths. Subject headings: line identifications
- spectra, laboratory

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Title: The Kitt Peak table of photographic solar spectrum wavelengths
Authors: Pierce, A. Keith; Breckenridge, James B.
1974kptp.book.....P Altcode:
No abstract at ADS

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Title: Radiation and structure of the solar atmosphere (Radiation
et structure de l'atmosphère solaire).
Authors: Athay, R. G.; Delbouille, L.; Pierce, A. K.; Rigutti, M.
1973IAUTA..15..129A Altcode:
No abstract at ADS

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Title: True Central Intensities of Fraunhofer Lines
Authors: Brault, J. W.; Slaughter, C. D.; Pierce, A. K.; Aikens, R. S.
1971SoPh...18..366B Altcode:
From observations made at Kitt Peak the true central intensities
of 40 Fraunhofer lines distributed between λλ 3083-7699, for the
center of the solar disk, are derived and given in tabular form. The
paper includes a description of the optical system - telescope and
spectrograph. The methods of observation and reduction of the data
are discussed.

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Title: Working Group on Central Line Intensities
Authors: Pierce, A. K.
1971IAUTB..14..116P Altcode:
No abstract at ADS

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Title: Working Group on Sunspot Spectra
Authors: Pierce, A. K.
1971IAUTB..14..115P Altcode:
No abstract at ADS

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Title: Radiation and structure of the solar atmosphere.
Authors: Athay, R. G.; Pierce, A. K.; Rigutti, M.
1970IAUTA..14..111A Altcode:
No abstract at ADS

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Title: The Solar Wavelength Program-Kitt Peak National Observatory
Authors: Brault, J. W.; Breckinridge, J. B.; Pierce, A. K.
1969BAAS....1Q.235B Altcode:
No abstract at ADS

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Title: The Solar Program of the Kitt Peak National Observatory
Authors: Pierce, A. Keith
1969SoPh....6..498P Altcode:
No abstract at ADS

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Title: The Chromospheric Spectrum Outside of Eclipse, lambda lambda
304O to 9266 A
Authors: Pierce, A. Keith
1968ApJS...17....1P Altcode:
Approximately 11500 chromospheric emission lines are listed from plates
taken at the McMath solar telescope with the slit of the spectrograph
placed tangent to the limb of the Sun. The ledger gives (1) solar
wavelengths, (2) rough eye estimates of intensity, (3) identifications
for both atomic and molecular lines, (4) laboratory wavelengths, and
(5) multiplet numbers. A brief discussion of selected elements and
lines is given in the text.

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Title: Energy from the Sun. (Book Reviews: Solar Radiation)
Authors: Pierce, A. Keith
1966Sci...154..639R Altcode:
No abstract at ADS

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Title: Report of the Working Group on Central Line Intensities
Authors: Pierce, A. K.
1966IAUTB..12..169P Altcode:
No abstract at ADS

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Title: Grinding and Figuring Equipment
Authors: Pierce, A. K.
1966IAUS...27...75P Altcode:
No abstract at ADS

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Title: Construction of a Bowen Image Slicer
Authors: Pierce, A. Keith
1965PASP...77..216P Altcode:
No abstract at ADS

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Title: Observations of the Flash Spectrum Outside Eclipse
Authors: Pierce, A. K.
1965PASP...77..137P Altcode:
No abstract at ADS

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Title: The Infrared Spectrum of the Sun
Authors: Pierce, A. Keith
1965ASPL....9..217P Altcode: 1965ASPL..428.....P
No abstract at ADS

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Title: The McMath solar telescope of Kitt Peak National Observatory
Authors: Pierce, A. Keith
1964ApOpt...3.1337P Altcode:
Available from <A
href="http://www.opticsInfoBase.org/abstract.cfm?id=13580;">http://www.opticsInfoBase.org/abstract.cfm?id=13580;</A>

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Title: Excitation-Temperature Equality in the Balmer Lines.
Authors: Pierce, A. Keith; Waddell, J., III
1964ApJ...140.1160P Altcode:
An analysis of observations of the Balmer lines suggest that the
excitation temperatures of these lines are equal, to within present
observational error.

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Title: The Coronal Spectrum of the July 20, 1963 Eclipse
Authors: Pierce, A. Keith; Slaughter, Charles D.
1963PASP...75..459P Altcode:
No abstract at ADS

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Title: Report of scientific sessions
Authors: Pierce, A. K.
1962IAUTB..11..316P Altcode:
No abstract at ADS

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Title: Analysis of Limb Darkening Observations
Authors: Pierce, A. K.; Waddell, J. H.
1961MmRAS..68...89P Altcode: 1961MmRAS..63...89P
No abstract at ADS

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Title: The Large Solar Telescope at Kitt Peak II
Authors: McMath, Robert R.; Pierce, A. Keith
1960S&T....20..132M Altcode:
No abstract at ADS

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Title: The Large Solar Telescope at Kitt Peak, II
Authors: Pierce, A. K.; McMath, R. R.
1960S&T....20..132P Altcode:
No abstract at ADS

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Title: The Large Solar Telescope at Kitt Peak I
Authors: McMath, Robert R.; Pierce, A. Keith
1960S&T....20...64M Altcode:
No abstract at ADS

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Title: The Large Solar Telescope at Kitt Peak, I
Authors: Pierce, A. K.; McMath, R. R.
1960S&T....20...64P Altcode:
No abstract at ADS

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Title: The Photosphere of the Sun.
Authors: Goldberg, Leo; Pierce, A. Keith
1959HDP....52....1G Altcode:
The continuous spectrum Solar constant Observed limb darkening Observed
solar energy distribution Observational models of the photosphere The
Fraunhofer spectrum Observational data The formation of Fraunhofer
lines The analysis of Fraunhofer lines General references

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Title: The Photosphere of the Sun
Authors: Pierce, A. K.; Goldberg, L.
1958HDA....52....1P Altcode:
No abstract at ADS

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Title: Performance of an Eight-Inch Babcock Grating in a Large
Vacuum spectrograph
Authors: Pierce, A. K.
1957JOSA...47....7P Altcode: 1957OSAJ...47....7P
No abstract at ADS

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Title: A High-Resolution Isophotometer.
Authors: Mohler, O. C.; Pierce, A. K.
1957ApJ...125..285M Altcode:
A modification of a microdensitometer that converts the instrument
into an isophotometer is described. There are two advantages of the
modified instrument. First, it is completely automatic in operation;
second, the accuracy of the intensity levels can be made very high

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Title: Preliminary Results with a Vacuum Solar Spectrograph.
Authors: McMath, Robert R.; Mohler, Orren C.; Pierce, A. Keith;
Goldberg, Leo
1956ApJ...124....1M Altcode:
New observations of the solar spectrum with a high-resolution vacuum
spectrograph reveal a wealth of detail in the cores of all Fraunhofer
lines observed both in the normal disk and in areas exhibiting
various kinds of solar activity. The lines show fluctuations in width,
intensity, and position over intervals as small as 2 seconds of arc. A
representative collection of photographs is presented, together
with tentative conclusions derived from inspection and preliminary
measurement. Measurements of Doppler shifts have been carried out in
considerable detail for the two lines Cr X 4626 and Ba+ X 5853. The
random turbulent velocity at the center of the disk is 0 70 km/sec
for the chromium line and O. km/sec for the ionized barium line. For
both lines the random turbulent velocity appears to increase toward
the limb. The velocity shifts observed for the Ha and sodium D lines
are of the same order of magnitude as those of the weaker metallic
lines. The disk observations of the Fraunhofer lines of hydrogen and
ionized calcium seem to he consistent with a qualitative model of the
low chromosphere, consisting of relatively hot clouds of gas and with
cooler regions both above and between the hot regions. Both the K2
emission in ionized calcium and the wide absorption features in Ha
seem to originate in the hot regions; from the appearance of these
line features near the limb it seems that the hot regions contribute
a substantial fraction of the hydrogen and ionized calcium emission
in the very low chromosphere. The profiles of Ha at the extreme limb
and of the K line and other strong metallic lines on the disk favor
the conclusion of Adams and Burwell that central self-reversal is a
general characteristic of most strong chromospheric profiles. The
similarity between the intensity and velocity fluctuations in the
core of the strong magnesium line X 5167 and in those of neighboring
weaker lines implies either a chromospheric origin for the centers of
these weaker lines or the extension of the photospheric granules into
the low chromosphere. The preliminary nature of the foregoing results
is emphasized.

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Title: Doppler Shifts in Solar Granules.
Authors: McMath, Robert R.; Mohler, Orren C.; Pierce, A. Keith
1955ApJ...122..565M Altcode:
No abstract at ADS

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Title: Introductory remarks: Some Observational Techniques and Basic
Data on Stellar Atmospheres
Authors: Pierce, A. Keith
1955stat.conf....1P Altcode: 1954stat.conf....1P
No abstract at ADS

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Title: Solar Limb Darkening in the Region λλ 7793-24388.
Authors: Pierce, A. Keith
1954ApJ...120..221P Altcode:
Observed values of limb darkening determined with a PbS cell and the
Snow telescope of the Mount Wilson Observatory are given for the near
infrared. The method of correcting the observed curves for seeing,
scattered light, and time constant is given in detail. The observed
brightness distribution extends from cos 0 = 1.00 to cos 6 = 0.10;
and covers the interval XX 7793-24388 with values at 26 different
wave lengths.

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Title: Photoelectric Observations of the Profile of HA in the Sun's
Spectrum.
Authors: Pierce, A. Keith
1954ApJ...120..233P Altcode:
The profile of Ha in the sun's spectrum for the center of the disk is
tabulated. The wings of the line show a depression of 1 per cent at 4
40 A from the line center. The central core of the line is asymmetrical
with the minimum intensity at -0.037 A.

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Title: The profile of Hα in the sun's spectrum.
Authors: Pierce, A. Keith
1954AJ.....59..189P Altcode:
The existing infrared equipment of the McMath-Hulbert Observatory
has recently been modified so that direct scanning of the visible
spectrum with a I P2 I photomultiplier can be carried out. Through
the kindness of Dr. I. Bowen we have been able to use a 6 X 8 inch,
15,000 g/inch grating ruled by Babcock. Tracings made in the green of
the fourth order show a resolution in excess of 250,000. But, because
of the low sensitivity of the I P2 I at Ha, wider slits were used so
that R = 150,000 for these observations. The grating has negligible
scattered light while the total ghost intensity is 2.0 per cent
in the fourth order. The position of the continuum and extent of
the wings of Ha were determined from tracings covering 200 to 300A
in length. Observations made at the sun's center show a measurable
depression of one per cent occurring at 40A from the line center. The
Doppler core of the line was observed at cos 6 = 1.00, o.86, 0.64,
0.42 and 0.25. At cos 0 = 1.0, the central parts of the line show a
distinct asymmetry in the direction that the red part is considerably
more rounded on the bottom than the violet. The minimum of intensity
occurs at -0.042A. At this point there often appears a sharp, weak
absorption line. The strongest absorption feature so far observed
has an equivalent width of 0.0036A, which corresponds to 1.5 X 1010
atoms in the second quantum level. The sharpness of the feature, a
half-width about 0. IA, implies the unreasonably low temperature, ~oo0K,
particularly since the hyperfine structure amounting to a separation of
components of 0.12A should appear. Hence its interpretation as hydrogen
absorption is uncertain. The absorption feature and the asymmetry of
the line disappear at the limb. The general asymmetry of the line can
be explained if we assume a complex emission core produced by jets or
small prominences, some having a radial velocity of 5 km/sec toward the
sun and others with a velocity of 8 km/sec outward from the sun. In
a general way this agrees with the H2, K2 emission in Ca. T. Royds
observed on Ha spectroheliograms that dark markings and the bright
emission markings accompanying spot disturbances showed best when the
second slit of the spectroheliograph was set 0.2A to the violet.' When
the slit was set to the red it was observed that the markings disappear
and the image is much less contrasty. Further observations will be
made on the relationship of the line profile to spectroheliograms.

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Title: Relative Solar Energy Distribution in the Spectral Region
10,000-25,000 a.
Authors: Pierce, A. Keith
1954ApJ...119..312P Altcode:
Tables are given of the observed relative solar energy distribution
for zero air mass in the wavelength interval 10,()()( 25,000 A. The
observations are based on measures made at Mount Wilson at the Snow
telescope with resolution-band pass 0.30 A. The calibration of the
spectral response of the equlpment was evaluated by observations of
a black-body source and a pyrometric arc. A detailed description of
the comparison sources and their use is given.

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Title: The 50-foot focal length vacuum spectrograph for solar
research.
Authors: McMath, R. R.; Mohler, O. C.; Pierce, A. K.
1954AJ.....59R.328M Altcode:
It is plain that an adequate study of the profiles of a large number
of Fraunhofer lines demands a spectrograph of high resolving power
and great linear dispersion. Through the kindness of Drs. I. S. Bowen
and H. W. Babcock we have been able to use one of their fine gratings,
6X8 inches, in our Pfund system.' With this arrangement we immediately
found an asymmetry and variable features in the center of Ha.2 However,
further work on faint solar lines and on the absorption spectrum of
iodine indicated a resolving power lower than anticipated with this
particular grating. Photoelectric traces made by placing the steep
portion of an absorption line or the very steep intensity change at
the zero order on the exit slit of the spectrometer indicated from the
strong random fluctuations of the signal that spectrographic seeing
was the undoubted cause of lowered resolution. For photographic work
the criteria for the design of large stellar spectrographs, as given
by I. S. Bowen,3 require that the resolving power of the photographic
plate be matched to the linear resolving power of the grating at the
focal plane. A photograph taken with a spectrograph approximating this
condition will show considerable graininess if a narrow slit of width
equal to the resolving power is used in the photometer. Where there is
ample light the use of a longer focal length and a larger scale permits
the use of wider microphotometer slits with a gain in smoothness of the
recording with no loss in resolving power. In addition, with the larger
scale spectrograph the slits are mechanically easier to construct and
the effects of dust, defects and non- parallelism of the slit jaws are
percentagewise less. The latter points are of considerable importance in
problems which involve photometry of details of the solar surface that
the slit intersects along its length. However, a longer focal length
aggravates the seeing problem. Following the high resolution work on
Ha and an experimental investigation of our spectrographic seeing,
both at Lake Angelus and at the Snow telescope at Mount Wilson,
Dr. McMath started in January 1954 the design and construction of
a large vacuum spectrograph which would completely eliminate the
spectrograph seeing problem, and which would give adequate scale and
vacuum wave lengths. The design utilizes the 50-foot focal length
off-axis mirror system of the existing McGregor Tower to form an image
of the sun at the first slit of a predisperser before the grating
spectrograph. The optical arrangement of the spectrograph follows
the design described by M. Czerny and A. F. Turner,4 but the mirrors
and grating are now placed in a vacuum tube 52 feet long and 4 feet
internal diameter. Other tube specifications are: Rolled and welded
plate, thickness ~` inch, reinforced with rings every four feet. The
end plates are 14' inches thick and are heavily reinforced with 6-inch
deep ribs of i-inch plate welded to the inside faces. Light from the
entrance slit located behind a quartz field lens which also acts as a
window to the vacuum tank is collimated by a i~-inch spherical mirror
and returned to the grating located several feet inside the head of
the tube. The dispersed beam is focused on the second slit by a second
i~-inch spherical mirror and after passing through a quartz window is
received by a photomultiplier. A third concave i~-inch mirror at the
far end of the tube is arranged so that a short region of the spectrum
can be returned to a photographic plate. All mirrors, and the grating
table, are provided with complete motions in all degrees of freedom
through the use of electrical motors. The final adjustments can be
made by push buttons after the tank has been pumped down and assumed
its slightly altered shape under the atmosphere pressure load of 700
tons. The head of the spectrograph is to be provided with air locks
at every point. The adjustment and repair of the slits,: or of the
photocell, are thus facilitated without destroying the vacuum of the
main tank. A special cassette and air lock will permit a quick plate
change to be made. The tank, constructed by Whitehead and Kales of
Detroit, proved to be vacuum-tight on erection. The first pump-down with
a Kinney vacuum pump, Model VSD-88i I, of 45 cubic feet displacement per
minute, required one hour to reach I cm pressure I mm after two hours. A
pressure of 70 microns has been obtained and it is expected that still
lower values will be achieved after the inside surfaces, painted with
red lead, have occluded their more volatile constituents. Tests have
shown that the rate of pressure rise on the tank is so small, 0.1 mm
rise per 24 hours, that it will be possible to pump out the tank at
night and then to shut off the pump during the operating day. This is
a necessary requirement as the pump, though on an isolated pier with
flexible connection to the tank, carries a perceptible vibration to the
optics. This spectrograph will allow the use of one of Babcock's superb
gratings in the fifth order, and should allow the grating to develop
its full resolving power of about 600,000. The linear dispersion in
the fifth order will be 6.92 mm per angstrom at 5000 A. This dispersion
should make3]possible faint line profile work containing a relatively
small instrumental contribution. The scattered light is to be evaluated
by interferometric and other methods. Precision measurements of profiles
of the stronger lines by photoelectric methods requires an exceptional
sky. Our experience has been that sky transparency over long intervals
of time is so rarely obtained that means of monitoring the background
intensity is very desirable. For this purpose we are planning to use a
modification of the system employed by Hiltner and Code.5 One photocell
will monitor a 200 A interval as passed by the predisperser through
the first slit, and the other will record the spectrum through the
second slit. Reflecting slits of stellite will allow one to guide
accurately on details seen through a Lyot filter which will present
a field bisected by the slit. 5.R. R. McMath and 0. C. Mohler,
J. Opt. Soc. Amer. 39, 903, `949. 2.Ap. J. in press. 3.Ap. J. is6,
5, 5952. 4.Zs. Phys. 6i, 792, 5930. 5.J. Opt. Soc. Amer. 40, `49,
5950. McMath-Hulbert Observatory, University of Michigan, Pontiac, Mich.

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Title: Table of Infrared Solar Lines, 1.4-2.5 μ.
Authors: Mohler, Orren C.; Pierce, A. Keith; McMath, Robert R.;
Goldberg, Leo
1953ApJ...117...41M Altcode:
Accurate wave lengths and measurements of equivalent width are given
for 888 solar lines in the spectral region 1. 2.5 . The number of
solar lines has been more than doubled, as compared with previous
preliminary studies in this spectral region. The wave lengths of
the solar lines are referred to those of the Fraunhofer lines in the
visible and very near infrared spectrum by the method of overlapping
orders. The root-mean-square errors of the infrared standard wave
lengths, as derived from repeated measurements of individual lines,
are +0.13 A for the l.6 region and +0.17 A for the 2.3 region. The
equivalent widths are preliminary. The estimated errors are between
10 and 100 per cent, depending upon the degree of blending. About 470
infrared solar lines have been tentatively identified with atoms of H,
K, C, At, Na, Si, Mg, Ca, Ni, and Fe and with first overtone lines
of CO. Comparisons between solar wave lengths and those measured in
the laboratory or predicted from term values reveal somewhat closer
agreement, on the average, between the solar and the predicted values
than between the solar and the laboratory values.

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Title: Model Solar Atmospheres.
Authors: Aller, Lawrence H.; Pierce, A. Keith
1952ApJ...116..176A Altcode:
An iteration method is described for obtaining model stellar
atmospheres when the temperature as a function of optical depth
is known. This process is applied to the solar atmosphere, using
an empirical temperature distribution based on observations of
limb darkening. The total pressure, the electron pressure, and the
absorption coefficient are tabulated as functions of the optical depth
for different hydrogento-metal ratios. In addition, two solar models
with He/H ratios of and are tabulated and compared with other models.

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Title: The Abundance of CO in the Sun and in the Earth's Atmosphere
Authors: Goldberg, Leo; McMath, Robert R.; Mohler, Orren C.; Pierce,
A. Keith
1952PhRv...85..481G Altcode:
No abstract at ADS

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Title: Identification of CO in the Solar Atmosphere
Authors: Pierce, A. K.; Goldberg, L.; McMath, R. R.; Mohler, O. C.
1952PhRv...85..140P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Abundance of CO in the Sun and in the Earth's Atmosphere
Authors: Pierce, A. K.; Goldberg, L.; McMath, R. R.; Mohler, O. C.
1952PhRv...85..418P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Structure of the Solar Atmosphere as Deduced from
Limb-Darkening Measures.
Authors: Pierce, A. Keith; Aller, Lawrence H.
1951ApJ...114..145P Altcode:
From solar limb-darkening measurements made at the McMath-Hulbert
Observatory and from the intensity distribution at the center of the
disk the temperature at optical depth, rX, is derived for a number of
wave lengths. The theoretical kx, based on the negative hydrogen ion as
the main source of opacity, appears to give an adequate interpretation
of the solar limb-darkening measurements in the visual and infrared
region of the solar spectrum. The boundary temperature of the sun is
about 45000.

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Title: Solar spectroscopy with echelles.
Authors: Pierce, A. Keith; McMath, Robert R.; Mohler, Orren
1951AJ.....56R.137P Altcode:
The echelle grating has the advantage of compressing a large spectral
range into a small angle about the blaze direction. A 150 X 75
mm echelle has been installed at the McMath-Hulbert Observatory
in an optical system using 14-foot focal length concave mirrors
for collimator and camera. The observed resolving power at N5000 is
about 250,000 with plate dispersion 2.9 mm/A. The instrumental profile
shows a narrow central peak with a strong satellite line at about .o5A
from the central peak. Photographs of the solar spectrum, prominence
spectra, and of a Zeeman triplet in a sunspot magnetic field have been
made. McMath-Hulbert Observatory, University of Michigan, Pontiac, Mich.

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Title: Structure of the solar atmosphere from limb darkening measures.
Authors: Pierce, A. Keith; Aller, Lawrence H.
1950AJ.....55..181P Altcode:
The darkening to the limb of the sun depends not only on the temperature
gradient but also on the absorptivity of the solar gases. From measures
of the intensity distribution, A (o), at the center of the solar disk
and from limb darkening measures it is possible to derive both the
temperature gradient and the wave-length dependence of the absorption
coefficient of the solar atmosphere. For this purpose we have utilized
Mulders's determination of A (o), together with limb darkening measures
made with the lead sulfide cell at the McMath-Hulbert Observatory. The
limb darkening curves were made at 10 different wave lengths in the
region 0.5 ~ to 2.3 ~ and cover 98.5 per cent of the solar radius. The
results confirm previous studies which show that the negative
hydrogen ion is the princi pal source of continuous absorption. The
extrapolation of the limb darkening curves to the boundary is small and
thus a reliable boundary temperature can be found. The observed parts
fit a Planck distribution corresponding to a boundary temperature of
45000K with an uncertainty of less than 1000K. From these studies we
hope to obtain Improved knowledge of the variation of temperature,
gas pressure, electron pressure, etc. with depth and thus finally an
improved model of the solar atmosphere. McMath-Hulbert Observatory,
University of Michigan, Lake Angelus, Pontiac, Mich.

---------------------------------------------------------
Title: Observations of Solar Limb Darkening Between 0.5 and
10.2&amp;mu
Authors: Pierce, A. K.; McMath, R. R.; Goldberg, Leo; Mohler, O. C.
1950ApJ...112..289P Altcode:
Measurements of solar limb darkening are tabulated for thirteen
wave lengths between 0.5 and 10.2 . Observations in the wave-length
region 0.5-2.2 were carried out with the McGregor Tower telescope and
spectrometer for the interval cos 0 = 1.0 to cos 0 = 0.16. Measurements
at three longer wave lengths were made with a Perkin-Elmer spectrometer
attached to the 24inch reflector and covered the interval cos 0 = 1.0
to cos 0 = 0.2. At certain wave lengths the near infrared measurements
agree with those of Abbot's to within 0.1 per cent; at other wave
lengths the systematic differences are as large as 1 per cent. It is
found that the degree of limb darkening decreases in the infrared
from 3.5 to 10.2 . This result is qualitatively consistent with a
systematic increase of the solar continuous opacity toward longer wave
lengths in the infrared, as predicted by theoretical calculations of
the absorption coefficient of the negative hydrogen ion.

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Title: New Solar Lines in the Spectral Region 1.97-2.49 μ.
Authors: Goldberg, Leo; Mohler, Orren C.; Pierce, A. Keith; McMath,
Robert R.
1950ApJ...111..565G Altcode:
Measurements of wave length and of percentage central absorption are
given for 109 solar lines in the region 1.97-2.49 of the infrared
solar spectrum. The lines were found on tracings obtained with
the high-dispersion spectrometers and Cashman PbS cells of the
McMath-Hulbert Observatory at Lake Angelus and at the Mount Wilson
Observatory. Forty-seven lines have been identified as arising from
neutral atoms of H, Na, Si, Mg, Al, Ca, and Fe. The relative scarcity
of solar lines in the 2.2 IL region is discussed, and a qualitative
explanation is given in terms of the variation with wave length of
the continuous absorption coefficient of H- combined with the solar
temperature gradient.

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Title: The 3n3 Band of Telluric CO2 in the Solar Spectrum
Authors: Pierce, A. K.; Goldberg, L.; Mohler, O. C.; McMath, R. R.
1950PhRv...78...74P Altcode:
No abstract at ADS

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Title: N2O Bands in the Solar Spectrum
Authors: Pierce, A. K.; McMath, R. R.; Mohler, O. C.; Goldberg, L.;
Donovan, R. A.
1950PhRv...78...65P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: An Improved Tracing of the Solar Spectrum Between 2. 9 and
3. 6 Microns
Authors: Mohler, Orren; Pierce, A. Keith
1949PASP...61..221M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar Observations with a Perkin-Elmer Infrared Spectrometer
Authors: Pierce, A. Keith
1949PASP...61..217P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Note on Methane in the Infra-Red Solar Spectrum
Authors: Pierce, A. K.; McMath, R. R.; Mohler, O. C.; Goldberg, L.
1949PhRv...76.1533P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Carbon Dioxide in the Infra-Red Solar Spectrum
Authors: Pierce, A. K.; Goldberg, L.; Mohler, O. C.; McMath, R. R.
1949PhRv...76.1848P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The solar curve of growth and the kinetic temperature of the
solar reversing layer.
Authors: Pierce, A. Keith; Goldberg, Leo
1948AJ.....53..202P Altcode:
An observational solar curve of growth for iron, titanium, and
vanadium was constructed from the gf values of the Kings and the
equivalent widths of Allen. Corrections for the variable continuous
opacity and limb darkening coefficient were applied to each line
before grouping according to excitation potential. For iron and
titanium the displacement of the groups gave a temperature of 46800
K, while for vanadium no proper temperature could be found because
of the non-linear relation between excitation potential and the
displacements. The observed curve of growth was fitted to a theoretical
curve based on the Milne-Eddington model. The "best" fit corresponds to
a most probable Doppler velocity of 2.5 km/sec and values AND/AXN = a
(as defined by Mitchell and Zemansky, Resonance Radiation and Excited
Atoms, Cambridge, 1934) equalling 0.01 for the weaker iron lines
and 0.05 for the stronger. The velocity parameter may be interpreted
in terms of either a kinetic temperature of 57000 plus a turbulent
velocity of 2.0 km/sec or a straight kinetic temperature of 19,5000
K. In an attempt to distinguish between the alternatives of thermal
or turbulent broadening, the half-widths of faint lines of several
elements of different atomic weight, ranging from carbon to nickel,
were determined from the Utrecht Atlas. The widths of these lines,
after correction for instrumental broadening, show a dependence on
atomic weight that accords well with the assumption of thermal widening
at a temperature of 16,0000 K. Observatory, University of Michigan,
Ann Arbor, Mich.

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Title: Mass Spectrographic Confirmation of the Isotopic Assignment
for the Long-Lived Radioactivity in Beryllium
Authors: Pierce, A. K.; Brown, F. W.
1946PhRv...70..779P Altcode:
No abstract at ADS