Author name code: mcmath
ADS astronomy entries on 2022-09-14
author:"McMath, Robert R."
------------------------------------------------------------------------
Title: Solar Instruments.
Authors: McMath, R. R.; Mohler, O. C.
Bibcode: 1962HDP....54....1M
Altcode:
Instruments for the measurement of the total solar radiation
Radio telescopes The image-forming instruments of solar astronomy
Construction and housing of solar telescopes Auxiliary instruments
for solar telescopes Instruments for the observation of solar eclipses
Some instrumental problems of solar observation Bibliography
Title: Telescope Driving Mechanisms
Authors: McMath, R. R.; Mohler, O. C.
Bibcode: 1961tele.book...62M
Altcode: 1961S&SS....1...62M
No abstract at ADS
Title: The Large Solar Telescope at Kitt Peak II
Authors: McMath, Robert R.; Pierce, A. Keith
Bibcode: 1960S&T....20..132M
Altcode:
No abstract at ADS
Title: The Large Solar Telescope at Kitt Peak, II
Authors: Pierce, A. K.; McMath, R. R.
Bibcode: 1960S&T....20..132P
Altcode:
No abstract at ADS
Title: The Large Solar Telescope at Kitt Peak I
Authors: McMath, Robert R.; Pierce, A. Keith
Bibcode: 1960S&T....20...64M
Altcode:
No abstract at ADS
Title: The Large Solar Telescope at Kitt Peak, I
Authors: Pierce, A. K.; McMath, R. R.
Bibcode: 1960S&T....20...64P
Altcode:
No abstract at ADS
Title: Solar Features Associated with Ellerman's "Solar Hydrogen
Bombs"
Authors: McMath, Robert R.; Mohler, Orren C.; Dodson, Helen W.
Bibcode: 1960PNAS...46..165M
Altcode:
No abstract at ADS
Title: Preliminary Results with a Vacuum Solar Spectrograph.
Authors: McMath, Robert R.; Mohler, Orren C.; Pierce, A. Keith;
Goldberg, Leo
Bibcode: 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.
Title: Photometry of Solar Flares.
Authors: Dodson, Helen W.; Hedeman, E. Ruth; McMath, Robert R.
Bibcode: 1956ApJS....2..241D
Altcode:
On the basis of photometric light-curves for 194 flares and subflares,
the following data have been derived. 1.Ha intensity often varies
differently in different parts of the same flare. 2.The change of Ha
intensity with time in a flare can be well represented by the series
of curves given by the equation iog =(iog Ii ax) t a(t-trnax), where
t is measured in minutes and a is positive for the ascending branch,
negative for the descending branch, and takes values between 0.40 and
0.00313. For the descending branch of the light-curve, a is always
smaller than for the ascending branch. The most usual value of a for
the ascending branch is 0.10; for the descending branch a is -<0.025
for 87 per cent of the cases. 3.Ha flare intensities have been measured
in units of both the local and the centra] continuum at x 6590. In the
former, average Ha intensity at flare maximum ranged from 0.66 for
subflares and 0.88 for flares of importance 1 to intensity 1.17 and
1.28 for flares of importance 2 and 3, respectively. In units of the
central continuum the average values are about 0.1 lower. The brightest
measured maximum was 1.9 times the local continuum for a flare at CMD 72
. 4.No convincing relationship has been found between rate of increase
of intensity and maximum intensity attained by the flare. However,
the slowest rate of increase apparently diminishes the chances of
attaining a maximum as bright as the contmuous spectrum. 5.There is
evidence for center-to4imb variation in numerous characteristics of
the Ha flares in this study. The slowest rates of rise and decline
were observed only for flares ithin 55 of the central meridian, and
the fastest rates of decline only for flares within 40 of the solar
limb. Average intensity in units of the local continuum increased
with increasing central meridian distance of the flares. In units of
the central continuum, the average intensity diminished from center
to limb. "Limb-darkening" equations for the flares and subflares are
as follows: Flares: lc=O.63+O.34COS 0, Subilares: lc=O.36+O.26CC)S
0. For flares of the same importance, average duration diminished with
increasing distance from the center of the disk. Near the center of
the disk, the Ha flare usua]ly lasted as long as, or longer than,
the associated ionospheric disturbance, but for flares near the
limb the reverse was true. 6.For the flares in this study, area and
intensity increase together, but the correlation coefficient of these
two measures is only 0.58 + 0.03 p.e. 7.Flare duration was associated
more closely with flare area than with maximum intensity. The duration
of flares as measured by photometric light-curves is much longer than
the average duration of flares reported in the Quarterly Bulletin of
Solar Activity. 8.The reported starting times of SID's usually fall
during the period of increasing intensity in the flare. Except in
unusual cases, SID's were not reported unless the flare intensity was
at least 0.8 of the local continuum and the area was of the order of
200 millionths of the solar disk. Near the limb the SID often lasts
longer than the Ha flare. 9.There is apparently less diminution from
center to limb in the ionizing radiation from flares than in Ha. 10. The
ionospheric disturbances were unusually small for certain large and
relatively bright flares associated with the onsets of 200-Mc/s noise
storms. 11. Examination of ionospheric records for the times of the
flares and subflares in this study has provided evidence for a new
type of flare-associated ionospheric effect, a gradual ionospheric
disturbance, in contradistinction to the sudden SID or Dellinger
effect. The 45 reported SID's have been augmented by 19 additional,
well-confirmed ionospheric disturbances and by 23 less certain
events. 12. There is no evidence to indicate that subflares are not
just smaller, fainter examples of the flare phenomenon. Flares and
subflares in this study have similar disk distributions and rates of
increase and decrease of intensity. Ionospheric disturbances accompanied
at least four of the brightenings here classified as subflares.
Title: Solar Spectroscopy with a Vacuum Spectrograph.
Authors: McMath, Robert R.
Bibcode: 1956ApJ...123....1M
Altcode:
No abstract at ADS
Title: Doppler Shifts in Solar Granules.
Authors: McMath, Robert R.; Mohler, Orren C.; Pierce, A. Keith
Bibcode: 1955ApJ...122..565M
Altcode:
No abstract at ADS
Title: The 50-foot focal length vacuum spectrograph for solar
research.
Authors: McMath, R. R.; Mohler, O. C.; Pierce, A. K.
Bibcode: 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.
Title: Table of Infrared Solar Lines, 1.4-2.5 μ.
Authors: Mohler, Orren C.; Pierce, A. Keith; McMath, Robert R.;
Goldberg, Leo
Bibcode: 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.
Title: Tower Telescopes and Accessories
Authors: McMath, R. R.
Bibcode: 1953sun..book..605M
Altcode:
No abstract at ADS
Title: Solar Research at the McMath-Hulbert Observatory
Authors: McMath, Robert R.
Bibcode: 1952PASP...64..151M
Altcode:
No abstract at ADS
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
Bibcode: 1952PhRv...85..481G
Altcode:
No abstract at ADS
Title: Identification of CO in the Solar Atmosphere
Authors: Pierce, A. K.; Goldberg, L.; McMath, R. R.; Mohler, O. C.
Bibcode: 1952PhRv...85..140P
Altcode:
No abstract at ADS
Title: The Limb Flare of may 8, 1951.
Authors: Dodson, Helen W.; McMath, Robert R.
Bibcode: 1952ApJ...115...78D
Altcode:
Published data indicate that flares have been observed at the limb
of the sun with elevations above the chromosphere of 8000-80,000
km. Continuous records of the solar limb and disk secured on Ha
spectroheliograms at the McMath-Hulbert Observatory show the outbreak
and development of a number of these flarelike prominences. They
range in form from relatively small cap-type prominences to the
great flare prominence of May 8, 1951. This latter object rose to a
height of 50,000 km in less than 90 seconds. During this interval the
Ha lines of the spectrum were 8-10 A wide and showed large Doppler
displacements. Throughout the remainder of the flare the change in
height was negligible, and the Ha spectrum lines were 5-6 A wide and
symmetrical. This flare prominence was four times as bright as the
undisturbed Ha disk, was accompanied by an increase in 200-Mc/sec
radiation from the sun, and was associated with a sudden disturbance
of the earth's ionosphere.
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.
Bibcode: 1952PhRv...85..418P
Altcode:
No abstract at ADS
Title: Photometric studies of solar flares.
Authors: Dodson, Helen W.; McMath, Robert R.; Hedeman, E. Ruth
Bibcode: 1951AJ.....56...37D
Altcode:
The development, at the McMath-Hulbert Observatory during 1950, of
a new and improved densitometer for the measurement of intensities
of features photographed on 35 mm motion picture film has permitted
an extension of the study of the "light curves" of solar flares. The
intensity of the flare is expressed in terms of the intensity of the
adjacent undisturbed disk as recorded on Ha spectroheliograms taken
with slits 0.4A wide. The study to date has included twenty-one flares
photographed in 1949, eight of importance I, nine of importance 2,
and four of importance 3. The intensities at maximum range from 1.6 to
5 times the intensity of the undisturbed Hot background. All flares
in this study for which the intensity of the flare was greater than
3 times that of the background were accompanied by sudden ionospheric
disturbances regardless of the location of the flare on the solar disk
or the area of the disturbance. Sudden ionospheric disturbances were
not restricted to association with only the largest and most intense
flares. On August 22, 1949 a flare of importance I, ~~O from the center
of the sun, was accompanied by a sudden ionospheric disturbance even
though it covered only 51 millionths of the solar hemisphere and reached
an intensity of only 2.4 at maximum. This flare occurred directly over
two spots. Two flares that took place on November I, 1949 in the same
plage area, about 400 from the center of the sun, present an interesting
anomaly. The first flare began at 1637 U.T., reached intensity 2.4 at
maximum and extended over 130 millionths of the solar hemisphere. It
was accompanied by a sudden ionospheric disturbance. The second flare
broke out in the same plage area at 1954 U.T. This flare was more
intense (2.75), larger (376 millionths) and lasted for a longer time
(66 minutes) but there is no report of a sudden ionospheric disturbance
for the period of its occurrence. Although both flares took place in
the same plage area and between the same two large spots, the detailed
regions involved in the two flares did not coincide or overlap in any
way. The light curves of the flares make possible not only a study
of the role of the maximum intensity in flare effects, but they also
permit an investigation of the time relationships between the first
indications of flare activity on the sun, the attainment of maximum
intensity, the onset of the sudden ionospheric disturbance, and the
relative durations of the solar and ionospheric phenomena. Although the
work to date includes only a portion of the flares recorded in 1949, it
is hoped that the photometric measures can be extended to include much
of the large body of observational material secured during the recent
solar maximum. MeMath-Hulbert Observatory, Lake A ngelus. Pontiac. Mich
Title: Solar spectroscopy with echelles.
Authors: Pierce, A. Keith; McMath, Robert R.; Mohler, Orren
Bibcode: 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.
Title: Reports: McMath-Hulbert Observatory. Lake Angelus, Pontiac,
Michigan
Authors: McMath, Robert R.
Bibcode: 1950AJ.....55..195M
Altcode:
No abstract at ADS
Title: Observations of Solar Limb Darkening Between 0.5 and
10.2&mu
Authors: Pierce, A. K.; McMath, R. R.; Goldberg, Leo; Mohler, O. C.
Bibcode: 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.
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.
Bibcode: 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.
Title: The 3n3 Band of Telluric CO2 in the Solar Spectrum
Authors: Pierce, A. K.; Goldberg, L.; Mohler, O. C.; McMath, R. R.
Bibcode: 1950PhRv...78...74P
Altcode:
No abstract at ADS
Title: N2O Bands in the Solar Spectrum
Authors: Pierce, A. K.; McMath, R. R.; Mohler, O. C.; Goldberg, L.;
Donovan, R. A.
Bibcode: 1950PhRv...78...65P
Altcode:
No abstract at ADS
Title: Telluric Bands of CH_{4} in the Solar Spectrum.
Authors: McMath, Robert R.; Mohler, Orren C.; Goldberg, Leo
Bibcode: 1949ApJ...109...17M
Altcode:
An all-reflecting telescope and spectrometer have been employed in
conjunction with a Cashman PbS cell to secure a direct-intensity map
of the solar spectrum in the region of 0.8-2.5 ~i with a resolution
of about 50,000. Four molecular-band systems at 1.66, 2.20, 2.32,
and 2.37 ~ have been identified as the P1 + V4~ V3 + P4 and ~2 + P3
transitions of CH4 in the earth's atmosphere. A preliminary analysis
of the wave numbers of the 2P3 rotational components indicates
second-order deviations from theory. The average half-spacing B0 is
found to be 5.163, as compared with the value B0 = 5.252 obtained by
Childs. A comparison of the 2P3 telluric line intensities with those
produced by a measured quantity of methane at room temperature leads
to a calculated methane abundance in the earth's atmosphere of 1.2
parts in a million by mass, and a temperature of -37° C
Title: New Solar Lines in the Spectral Region 1.52-1.75 μ.
Authors: Goldberg, Leo; Mohler, Orren C.; McMath, Robert R.
Bibcode: 1949ApJ...109...28G
Altcode:
Accurate wave lengths and measurements of percentage central absorption
are given for nearly three hundred new solar lines discovered in the
region 1.52-1.75 ~ of the infrared solar spectrum. The lines were found
on high-resolution, direct-intensity tracings of the spectrum obtained
at the McMath- Hulbert Observatory with the McGregor spectrometer
and a Cashman cell. Ninety-three of the lines have been identified as
belonging to neutral atoms of C, Mg, Al, Si, Fe, Mn, and Ni, mainly
on the basis of wave lengths computed from term values. In addition,
the third, seventh, and eighth members of the Brackett series of
hydrogen have been identified, together with the Na I 4s-4p doublet
at XX 22,054 and 22,081. INTRODUCTIO
Title: Note on Methane in the Infra-Red Solar Spectrum
Authors: Pierce, A. K.; McMath, R. R.; Mohler, O. C.; Goldberg, L.
Bibcode: 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.
Bibcode: 1949PhRv...76.1848P
Altcode:
No abstract at ADS
Title: Solar Filament of September 7, 1948
Authors: Dodson, Helen W.; McMath, Robert R.
Bibcode: 1948PASP...60..366D
Altcode:
No abstract at ADS
Title: Simultaneous observations of solar flares, surges, and
high-speed dark flocculi
Authors: McMath, R. R.; Mohler, O.
Bibcode: 1948Obs....68..110M
Altcode:
No abstract at ADS
Title: A Solar Infrared Reflecting Spectrometer
Authors: McMath, Robert R.; Mohler, Orren C.
Bibcode: 1948S&T.....7..143M
Altcode:
No abstract at ADS
Title: New Bands in the Telluric Spectrum
Authors: McMath, Robert R.; Mohler, Orren
Bibcode: 1948PASP...60..119M
Altcode:
No abstract at ADS
Title: Recent developments in infra-red solar spectroscopy.
Authors: McMath, R. R.; Mohler, O. C.; Goldberg, L.
Bibcode: 1948AJ.....54Q..44M
Altcode:
Since the late fall of 1947, the ~cGregor tower of the McMath-Hulbert
Observatory has been used for study of the infra-red solar spectrum
beyond the photographic limit. A specially designed, all-mirror optical
system and Pfund-type grating spectrometer, with monochromator,
have been used in conjunction with a Cashman leadsulphide cell to
obtain direct-intensity tracings of the solar spectrum over the
entire region between 8ooo and 25000 A. The spectrum is re corded on
a scale of about five millimeters per angstrom. In the 15000 X region,
lines with separation of 0.3 angstroms are just resolved. Water vapor
absorption almost completely obliterates the spectrum in the regions I
.3-1.5 microns and 1.75-1.95 microns. The intervening portions of the
spectrum, however, are relatively clear and contain a wealth of solar
atomic lines, as well as telluric molecular lines and bands. Progress in
identification has been slow, largely because of the complete absence
of high-resolution laboratory studies in this region of the infra-red
spectrum. Approximately 200 solar atomic lines have been identified
in the infra-red spectrum on the basis of wave lengths computed from
known atomic energy levels. The elements for which lines have been
found include Fe, Si, Na, AIg, Al, C, Ca, as well as the third and
seventh members of the Brackett series of hydrogen. The vast majority
of these lines have excitation potentials higher than five volts. Band
systems of molecules originating in the earth's atmosphere constitute
some of the most interesting features of the infra-red spectrum. Among
these are four CO1 bands in the 1.6 micron region, which have been
resolved for the first time, and three strong bands of CO1 at 2.1
microns. Among the identified molecular bands, those of ammonia and
methane are particularly noteworthy. The evidence for ammonia as
a constituent of the earth's atmosphere is very strong, while the
evidence for methane is conclusive. Mc Math- Hulbert Observatory,
Pontiac, Mich. and University of Michigan Observatory, Ann Arbor, Mich.
Title: The use of a high dispersion spectrograph in the wave-length
region 1.0 to 2.0 microns.
Authors: McMath, Robert R.; Mohler, Orren
Bibcode: 1948AJ.....53R.114M
Altcode:
The recent development of photoconductive cells, sensitive in the near
infra-red, has made possible the observation of the solar spectrum with
a dispersion not previously possible. The McGregor tower telescope of
the McMathHulbert Observatory and the McGregor Littrowtype spectrograph
have been provided with a lead-sulfide, photoconductive cell, and means
for recording the cell output. With this equipment we have produced a
complete map of the infra-red solar spectrum on a scale of 1.6 mm/A,
ending at 2o,6ooA. The wave-length limit of the map is set by the
strong absorption of the telescope objective and the spectrograph
collimator-camera lens. The measured resolving power on tracings
obtained with this equipment is 32,000 at i6,oooA. Observations at
large and small zenith distances from the sun have been made to aid
in separating solar lines from the general background of terrestrial
lines in this region of the solar spectrum. Many atomic lines have been
identified on the first tracings obtained. Mc Math-Hulbert Observatory,
University of Michigan, Lake Angelus, Pontiac, Mich.
Title: A reflecting spectrometer for the solar infra-red.
Authors: McMath, Robert R.; Mohler, Orren C.
Bibcode: 1948AJ.....53R.200M
Altcode:
In order fully to utilize the possibilities of the new photoconductive
infra-red detectors, such as the lead-sulfide cells now constructed
by R. J. Cash man at the Northwestern Technological Institute, a
reflecting optical system must be employed. Experiments during the
past year (1947) at the McMath-Hulbert Observatory have revealed so
many new and important features of the solar infra-red spectrum under
high dispersion, that we have designed and constructed a reflecting
spectrometer for use wi th the McGregor tower telescope. One of the
original telescopes of the McMath-Hulbert Observatory, a ~o-21-inch
Cassegrainian telescope of equivalent focal length 45 feet, and a
calcium fluoride prism monochromator constitute the image-forming and
predispersing system that precede the main spectrograph. Since our
interest is primarily in highly dispersed solar spectra, we have used
an aluminized speculum metal diffraction grating as the dispersing
element. The grating we are now using has been very kindly loaned to
us by the Mount Wilson Observatory. It is ruled with 600 lines per
millimeter and is very bright in the first order infra-red at about
20,OOOA wave length. The chief problem encountered in the design of
any spectrometer is the provision of an absolutely smooth rotation
of the grating about an axis parallel to its rulings. This problem
is comparable to that of producing an errorless drive for a large
telescope, and the long experience of Dr. McMath in the construction
of telescope drives led to the following solution. The grating table
is mounted on a specially selected precision grinder spindle, which
acts as the axis of rotation for the grating. The grating table is
rotated by steel belts attached under tension to a lapped nut that is
driven by a precision ground lead screw. Both the lead screw and the
spindle were obtained through the courtesy of the Ex-Cell-O Corporation
of Detroit, Michigan. They have proved to be entirely satisfactory
under all tests that we have applied. Especial care was necessary to
eliminate vibration set up by the grating drive motor, and to prevent
transmission of minute stresses to the grating table as it rotated. The
drive motor is mounted on a lead pad on the concrete floor of the
McGregor spectrograph, while the grating table is carried on the
isolated pier that supports the grating and collimating lens of the
McGregor Littrow spectrograph. As further precautions, the drive motor
is connected to the first reduction gears by a soft rubber belt, and
the drive shafts connecting the several reducing units are constrained
to transmit only rotation, while remaining free to move over short
distances in a longitudinal direction. No errors are detectable in
the drive when the spectrum is examined visually with a twenty power
microscope. As already mentioned, the grating drive is carried on the
collimator pier of the McGregor Littrow spectrograph. Also on this
pier are the 6-inch aperture, ~77-inch focal length, collimating and
image-forming mirrors. The mirrors and grating drive are attached to
the pier in such a way that only a few minutes are required to place
either the reflecting spectrometer or the refracting McGregor Littrow
system into use. The same entrance slit serves for both instruments. We
have adopted the Pfund optical system because it keeps aberrations at a
minimum, and visual examination of the higher order spectra shows that
the definition of the spectrum lines is very good indeed. The spectrum
is finally focused on a second, exit, slit which selects the narrow
region of the spectrum that falls on the lead- sulfide cell to produce
the photoelectric signal. As the grating is rotated by the drive motor,
the spectrum sweeps slowly across the second slit, and in this way,
scanning of any wave length region can be effected. Variations in
intensity occurring in the spectrum are recorded, after appropriate
amplification of the photoconductive signal, on a Leeds and Northrup
Speedomax Recorder. Two scanning speeds are provided, 0.10 and 0.05
mm/sec. At IO,500A, these linear speeds correspond to o.2~A/sec
and 0.1 2A/sec, since the linear dispersion at this wave length is
2.~~A/mm; but in the region of 22,OOOA the dispersion has increased to
I .87A/n~m with correspondingly slower rate of scan in wave length. The
recording paper is driven at 0.644 mm/sec, or 6.44 times the fastest
(o. 10 mm/sec) scanning speed, hence the resulting dispersions on the
recording paper are 2.65 mm/A at 10,500A and ~3.43 mm/A at 22,OOOA. The
measured resolving power on the recording paper is 22,000 at IO,500A and
44,000 at 22 ,000A. This resolving power is determined entirely by the
slit width, which is 0.20 mm for both entrance and exit slits. There
are almost no laboratory standards for aiding the identification of
atomic lines with wave length longer than 20,OOOA but we have observed
the third member of the Brackett series of hydrogen at 21 ,655.7A,
and the two sodium lines 4S 15 - 4p 2P~~, 22,052.7A (predicted); and
45 25 - 4p 2P~, 22,079.4A (predicted). This pair of lines has been
observed in emission in the laboratory. Measurements of wave lengths
and identifications of solar atomic lines are being made, and we hope
to complete a list of solar lines extending to 25,OOOA. McMath-Hulbert
Observatory, Lake Angelus, Pontiac, Mich.
Title: High-Dispersion Solar Spectrum in the 10,000 A to 20,000
A Region
Authors: McMath, Robert R.; Mohler, Orren C.
Bibcode: 1947PASP...59..267M
Altcode:
No abstract at ADS
Title: Evidence for coronal absorption on the solar disk.
Authors: McMath, Robert R.; Goldberg, Leo; Mohler, Orren C.
Bibcode: 1947AJ.....52R.156M
Altcode:
A broad, diffuse absorption line at 637A.45 I.A. + 0.01 has been found
in the spectrum of the solar disk on plates obtained with the McGregor
sbectrograph and the 70-ft. tower telescope of the McMath-Hulbert
Observatory. Its width has been estimated at 0.3 to 0.4 A. The line
is seen very faintly at the center of the disk, becoming strongly
accentuated at the limb. It appears equally intense all around the
limb and no significant variations in intensity or in wave length
have been found. The appearance of the line and the closeness of its
position to that of the red coronal line (given by Lyot as X6374.5I +
0.03) suggest the possibility that the absorption line arises from
atoms of Fe x. The evidence for or against the identification as Fe
x is discussed, the results at present being inconclusive. If the
line is due to Fe x, its intensity and distribution around the limb
are such that a considerable abundance of Fe x must be present in the
chromosphere. In this connection attention is called to the observation
by H. D. and H. W. Babcock' of a similar diffuse absorption line
at X6374.40 in the flash spectrum outside of eclipse. The Babcocks
reported that the line was flanked by emission components on either
side. A predicted line of Fe I (ziC2o - e702) occurs at X6374.43. No
other members of this multiplet have been observed with certainty in
the solar spectrum, however, and the width of the observed absorption
line makes its identification as predicted Fe I unlikely, unless it
is closely blended with another faint line. A search has been made
for a similar absorption line at the position of the green coronal
line 5302.86, identified by Edlen as arising from Fe xiv. No such
absorption line has been found. It is pointed out that excitation
conditions in the chromosphere favorable for the presence of Fe
x would not necessarily produce Fe xiv. I.Pub. A. S. P. 46, 132,
1934. McMath-Hulbert Observatory, Lake Angelus, Pontiac, Mich.
Title: A description of the Francis C. McMath Memorial 24-inch
reflecting telescope
Authors: McMath, Robert R.
Bibcode: 1946PAAS...10..138M
Altcode:
No abstract at ADS
Title: A report on the solar prominence radial velocity program of
the McMath-Hulbert Observatory
Authors: McMath, R. R.; Sawyer, H. E.; Brodie, John; Mohler, Orren
Bibcode: 1946PAAS...10...59M
Altcode:
No abstract at ADS
Title: Heber Doust Curtis, 1872-1942.
Authors: McMath, Robert R.
Bibcode: 1944ApJ....99..245M
Altcode:
No abstract at ADS
Title: The Francis C. McMath memorial 24-inch reflecting telescope
of the McMath-Hulbert Observatory
Authors: McMath, Robert Raynolds
Bibcode: 1943POMic...8...95M
Altcode:
No abstract at ADS
Title: The Julius F. Stone spectroheliograph for the determination
of solar atmospheric radial velocities
Authors: McMath, Robert Raynolds
Bibcode: 1943POMic...8..141M
Altcode:
No abstract at ADS
Title: The measurement of space motions of solar prominences
Authors: McMath, Robert Raynolds; Sawyer, Harold E.; Mohler, Orren C.
Bibcode: 1943POMic...8..123M
Altcode:
No abstract at ADS
Title: A method of measuring radial velocities in solar prominences
Authors: McMath, Robert Raynolds; Sawyer, Harold E.; Mohler, Orren C.;
Brodie, John
Bibcode: 1943POMic...8...57M
Altcode:
No abstract at ADS
Title: Heber Doust Curtis, 1872-1942
Authors: McMath, Robert R.
Bibcode: 1942PASP...54...69M
Altcode:
No abstract at ADS
Title: The McGregor Building and Tower Telescope of the McMath-Hulbert
Observatory
Authors: McMath, Robert R.
Bibcode: 1940Natur.146..287M
Altcode:
No abstract at ADS
Title: The Doppler Effect in an Eruptive Prominence
Authors: McMath, Robert R.; Pettit, Edison
Bibcode: 1939PASP...51..154M
Altcode:
No abstract at ADS
Title: Location of Velocity Changes in a Class IIIb Prominence
Authors: McMath, Robert R.; Sawyer, Harold E.
Bibcode: 1939PASP...51..165M
Altcode:
No abstract at ADS
Title: Motion pictures of small chromospheric flocculi
Authors: McMath, R. R.
Bibcode: 1939MNRAS..99..559M
Altcode:
No abstract at ADS
Title: The tower telescope of the McMath-Hulbert Observatory
Authors: McMath, Robert Raynolds
Bibcode: 1939POMic...7....1M
Altcode: 1939POMic...7.....M
No abstract at ADS
Title: A review of Lake Angelus prominence observations
Authors: McMath, Robert Raynolds; Sawyer, Harold E.
Bibcode: 1939POMic...7..191M
Altcode:
No abstract at ADS
Title: The development of eruptive prominences
Authors: McMath, Robert R.; Pettit, Edison
Bibcode: 1939PAAS....9..159M
Altcode:
No abstract at ADS
Title: Prominence Studies.
Authors: McMath, Robert R.; Pettit, Edison
Bibcode: 1938ApJ....88..244M
Altcode:
Eruptive prominences.-Data for seven new eruptive prominences conftrm
the laws of motion previously stated. The end velocity is now shown
to revert occasionally to a whole multiple of the second preceding
velocity, which explains some apparent excep- tions to the second
law. One prominence reached the unparalleled height of 1,550,000 km
and another the record velocity of 728 km/sec. The former was near the
north pole of the sun. The dilemma of light-pressure-A calculation of
the Milne effect shows that we can- not assume that light-pressure
balances gravity at the sun's surface. Velocities of more than
100 km/sec are developed in a few minutes from an initial 10 km/sec
velocity. Calcium tends to separate widely from hydrogen. Prominences
of class 111.-The motions in the fountain-like loops of class IIIb
prominences are down both branches from the ends of the bright tops
of the arches. Practically all obey the first law, and about 20 per
cent the second law of prominence motion; 7 cases show no change in
velocity. Ejections-Small faint lumps of chromospheric matter are
sometimes ejected from a spot area, often at considerable angles
to the vertical. These ejections seem to move in nearly straight
trajectories and do not return. Centers of attraction-Examination of
the dissolution of an active prominence pro- jected on the disk shows
that centers of attraction are not visible as surface markings. With
one exception, prominence streamers have always been seen to enter
centers of attraction from one side only. Fifty per cent of all the
streamers from class I promi- nences measured followed both laws of
prominence motion. Coronal prominences -When a center of attraction
becomes very active, long stream- ers not connected with the active
prominence enter the center of attraction from great heights. These
seem to come from space in the middle or outer corona. They obey both
laws of motion of eruptive prominences
Title: A Quasi-Eruptive Prominence Observed in Hydrogen
Authors: McMath, R. R.; Pettit, Edison
Bibcode: 1938PASP...50..240M
Altcode:
No abstract at ADS
Title: Motions in the Loops of Prominences of the Sunspot Type,
Class III b
Authors: McMath, R. R.; Pettit, E.
Bibcode: 1938PASP...50...56M
Altcode:
No abstract at ADS
Title: No. 597. Prominence studies.
Authors: McMath, Robert R.; Petitt, Edison.
Bibcode: 1938CMWCI.597....1M
Altcode: 1938QB4.M93n597....
No abstract at ADS
Title: An Eruptive Prominence of Record Height and Velocity
Authors: McMath, R. R.; Pettit, E.; Sawyer, H. E.; Brodie, J. T.
Bibcode: 1937PASP...49..305M
Altcode:
No abstract at ADS
Title: Some New Prominence Phenomena
Authors: McMath, R. R.; Pettit, E.
Bibcode: 1937PASP...49..240M
Altcode:
No abstract at ADS
Title: Prominences of the Active and Sun-Spot Types Compared
Authors: McMath, Robert R.; Pettit, Edison
Bibcode: 1937ApJ....85..279M
Altcode:
Tue tower ielescope.-The 50-foot tower telescope at Lake Angelus,
Pontiac, Michi- gan, records solar phenomena by means of the
motion-picture camera. All instru- mental motions are electrically
driven; the coelostat flat and camera are operated by the McMath-Hulbert
controlled frequency drive and declination control. The scout camera
and spectral-line control .-B oth H and K are used, K for the motion-
picture camera; the H line, thrown to one side, enters a plate camera
so that a promi- nence under observation can be photographed and
developed for inspection at any time. To set the H and K lines on
the slits of the spectroheliograph and to check their posi- tions
an auxiliary fixed slit fed by a mercury arc is used. Observing and
measuring-For the bulk of the work a focal length of 40 feet was used
for the solar image. Exposure is determined by a photronic photometer
and is usually of the order of 20-25 seconds on prominences with 2~
seconds between expo- sures. The films are measured by projecting the
frames upon a milk-glass screen; the position of a knot or streamer
along its trajectory is determined with a flexible celluloid scale or,
in some cases where the motion is small, by a cathetometer. Activity
within a sun-spot group.-The ejection of bright flocculi has been
observed. The velocity is about 100 km/sec, and the phenomenon
occurs at intervals of about an hour. Prominences of the sun-spot
type-Detailed measurements of the motions of knots and loop ends along
their trajectories show that class III prominences obey the first law
of motion of eruptive prominences and, when the projection factor is
small, the sec- ond law as well. Many streamers have their origin high
above the chromosphere, and the appearance cannot be accounted for
by Doppler effect. The simplest explanation requires the presence of
a chromospheric atmosphere in the corona. Surges-These rise from and
sink back into the chromosphere in the vicinity of sun-spots, forming
class hId. They are mostly small, but one was observed which reached
a height of 8o,ooo km with a velocity of 240 km/sec. The ftrst law
of motion seems to prevail in this type also. Quasi-eruptions-A case
where an active prominence rose to a great height, nearly reaching the
eruptive stage, before being drawn back to the center of attraction
is cited. This forms a connecting link between active and eruptive
prominences and sub- stantiates the idea that eruptions are extreme
cases of the active or class Ilic stages. Active prominences.-Detailed
measurements on these prominences show that the streamers and knots
move along their trajectories, obeying both laws of motion of eruptive
prominences
Title: A short-lived solar disturbance
Authors: Petrie, Robert Methven; McMath, Robert Raynolds
Bibcode: 1937POMic...6...43P
Altcode:
No abstract at ADS
Title: No. 568. Prominences of the active and sun-spot types compared.
Authors: McMath, Robert R.; Petitt, Edison.
Bibcode: 1937CMWCI.568....1M
Altcode: 1937QB4.M93n568....
No abstract at ADS
Title: A short-lived solar disturbance -- Motion picture film
Authors: Petrie, R. M.; McMath, R. R.
Bibcode: 1936PAAS....8Q..49P
Altcode:
No abstract at ADS
Title: The new solar tower of the McMath-Hulbert Observatory
Authors: McMath, R. R.
Bibcode: 1936PAAS....8R.215M
Altcode:
No abstract at ADS
Title: New method of driving equatorial telescopes
Authors: McMath, R. R.; Greig, W. A.
Bibcode: 1936PAAS....8Q..16M
Altcode:
No abstract at ADS
Title: The spectroheliokinematograph
Authors: McMath, Robert Raynolds; Petrie, Robert Methven
Bibcode: 1934POMic...5..103M
Altcode:
No abstract at ADS
Title: A new method of driving equatorial telescopes
Authors: McMath, Robert Raynolds; Greig, Walter A.
Bibcode: 1934POMic...5..123M
Altcode:
No abstract at ADS
Title: Some new methods in astronomical photography, with application
to moving pictures of celestial objects
Authors: McMath, Francis C.; McMath, Robert Raynolds; Hulbert,
Henry Schoolcraft
Bibcode: 1932POMic...4...53M
Altcode:
No abstract at ADS
Title: The McMath-Hulbert telechron driving-clock
Authors: McMath, Robert R.
Bibcode: 1930PA.....38..460M
Altcode:
No abstract at ADS