explanation blue bibcodes open ADS page with paths to full text
Author name code: vrabec
ADS astronomy entries on 2022-09-14
author:"Vrabec, Dale"
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Title: Relationships Between MMF Trajectories and Sunspot Penumbral
Filament Structure
Authors: Vrabec, D.; Chapman, Gary A.
1974BAAS....6T.296V Altcode:
No abstract at ADS
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Title: Streaming Magnetic Features Near Sunspots
Authors: Vrabec, D.
1974IAUS...56..201V Altcode:
No abstract at ADS
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Title: Magnetic Fields Spectroheliograms from the San Fernando
Observatory
Authors: Vrabec, D.
1971IAUS...43..329V Altcode:
No abstract at ADS
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Title: Preliminary Magnetic-Field Spectroheliogram Data from San
Fernando Observatory.
Authors: Vrabec, Dale
1970BAAS....2..352V Altcode:
No abstract at ADS
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Title: A New Solar Observatory in California
Authors: Mayfield, E. B.; Vrabec, D.; Rogers, E.; Janssens, T.;
Becker, R. A.
1969S&T....37..208M Altcode:
No abstract at ADS
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Title: A 61-cm Aperture Evacuated Solar Telescope and
Spectroheliograph.
Authors: Vrabec, Dale; Rogers, Ernest H.
1968AJS....73R..81V Altcode:
A 61-cm aperture, f/20 reflecting solar telescope and associated
spectroheliograph are currently under construction for the Aerospace
Solar Observatory. The telescope configuration is Cassegrain, with
3X relay to a coude' focus by an elliptical tertiary mirror, four
flats and a field lens. The mounting is asymmetrical equatorial,
and the telescope tube also functions as a spar for mounting
auxiliary instrumentation. All mirrors are Cer-Vit. An entrance
window and the field lens seal off the internal optical path which is
evacuated. The primary solar image scale is 60 microns/sec of arc. The
spectroheliograph is an f/20, single pass, Littrow type of 300 cm focal
length. Dispersion is produced by any one of three turret-mounted 250X
150 mm plane reflectance gratings, providing three different blazes. A
slightly telephoto triplet lens functions as collimator and camera. The
spectroheliograph has two identical exit slits, permitting two 70 mm
cine film frames to be exposed simultaneously. Subsequent photographic
subtraction of each image pair produces a time-lapse film record of
either Zeeman or Doppler fields. The necessary compensation of spectrum
line curvature is accomplished by curving the entrance and two exit
slits an identical and fixed amount, and incorporating an adjustable
two-lens spectrum line curvature compensating system. Scanning is
accomplished by pivoting the optical portion of the spectroheliograph
as a unit about a horizontal axis located beneath the grating, parallel
to the slits and equidistant from them. The field lens placed 20 cm
above the entrance slit images the telescope exit pupil on the pivoting
axis. During scanning, the solar image and camera are fixed. Normally,
a servo driven, water-cooled field stop at the Cassegrain focus is
activated, which limits the instantaneous telescope field to a narrow
strip centered on the entrance slit.
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Title: Sixty-Two Hour (Continuous) Solar Movie for the Study of
Supergranules.
Authors: Janssens, Thomas J.; Rogers, Ernest H.; Vrabec, Dale
1967AJ.....72Q.806J Altcode:
In order to study the time changes of slowly varying supergranules an
Ha telescope was set up above the arctic circle at Thule, Greenland,
where continuous movies were made of the Ha network taking advantage
of the "midnight sun. "Installation of the telescope and the observing
conditions experienced are described. Surprisingly, these included
extended periods of excellent seeing. The photographs were taken
at intervals of 3 sec at Hat 0.6 A of a quiet region on the sun's
equator. Due to solar rotation, the guiding had to be adjusted every
12 h. The data record of the 62 h period of observing consists of
about 70 000 frames, from which certain frames are selected to obtain
movies of various lengths. Three interesting phenomena which are
presented are very fast periodic spiculelike absorption features in
the absorption network, coherent waves of velocity patterns seen in
areas between the network, and the very slow changes in the pattern of
the network and the cells. At the time of this writing a quantitative
study is not complete, but well under way. A detailed study of many
interesting phenomena will have to await construction of a high-speed
computeroriented microdensitometer. This work was conducted under
U. S. Air Force Space Systems Division Contract AF04 (695) - 1001.
