VIII/28 Bell Laboratories H I Survey (Stark+ 1992)
The Bell Laboratories H I Survey
Stark A.A., Gammie C.F., Wilson R.W., Bally J., Linke R.A.
<Astrophys. J. Suppl., 79, 77 (1992)>
=1992ApJS...79...77S 1992ApJS...79...77S
ADC_Keywords: H I data; Interstellar medium; Surveys; Radio lines
Description:
The sky north of declination -40° was observed in the 21cm line
of atomic hydrogen with the FWHM=2° beam of the 20 foot horn
reflector at AT&T Bell Laboratories, Crawford Hill. The survey covers
a velocity range of 654km/s centered on the Galactic standard of
rest, with 5.3km/s wide filters. This survey is distinguished by its
sensitivity to low surface brightness features (antenna temperature
about 50mK) and relative freedom from sidelobe contamination.
High-velocity clouds are extracted and catalogued automatically. The
data are presented in declination zones in equatorial and polar
coordinates, and as R.A. - velocity images.
Introduction:
Observations were made as drift scans along even declinations between
-40° and +90° at the epoch (1981) of the observations. The
horn antenna has a FWHM beam size of 2° at 21cm. This large beam
made it possible to cover the whole visible sky in 66 constant
declination scans. The survey is undersampled in declination (one beam
width sampling) and oversampled in right ascension (roughly quarter
beamwidth sampling). The average rms noise of spectra taken at all
declinations is 0.017K in 5.2km/s wide channels, although in some
cases baseline problems make the survey unreliable at this level. The
survey contains 19,248 spectra.
The data are in FITS format.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This File
sky.dat 43 145 List of FITS files with images of the integrated
21cm flux in each velocity channel
ravel.dat 17 66 List of FITS files with images of the antenna
temperature in declination ranges
fits/* . 501 All FITS files described in sky.dat and ravel.dat
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Byte-by-byte Description of file: sky.dat
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Bytes Format Units Label Explanations
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1- 4 I4 km/s cVel Central velocity of the channel
(limits are cVel±5km/s)
6- 17 A12 --- FITS-Nfile North polar cap image in this channel,
in "fits" subdirectory;
19- 30 A12 --- FITS-Wfile Whole sky (outside polar caps) in this channel
in "fits" subdirectory;
32- 43 A12 --- FITS-Sfile South polar cap image in this channel,
in "fits" subdirectory;
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Byte-by-byte Description of file: ravel.dat
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Bytes Format Units Label Explanations
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2- 4 I3 deg cDec Central declination
6- 17 A12 --- FITSfile File in "fits" subdirectory fits
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Modifications:
The file names from the tape were renamed to distinguish the different
coordinate systems and projections easily. In the notes some
information from the HISTORY records in the FITS headers was appended.
The data were read with the FITS routines from the IDL ASTRONOMY
USER'S LIBRARY maintained by Wayne Landsman
().
* 21-Dec-2002: files sky.dat and ravel.dat containing the list of FITS
files were added.
(End) N. G. Roman and N.P.M. Kuin [NASA/SSDOO/ADC] 11-Apr-1995