VIII/7A Hat Creek High-Latitude H I Survey (Heiles+ 1974-1976)
The Hat Creek High-Latitude H I Survey
Heiles C. and Habing H.J.
<Astron. & Astrophys. Suppl., 14, 1 (1974)>
=1974A&AS...14....1H 1974A&AS...14....1H
ADC_Keywords: Radio sources ; Surveys ; H I data
Description:
This survey consists of H I 21-cm spectra covering the entire northern
sky with absolute Galactic latitude |b|>10 degrees and declination
dec>-30degrees. The observations were made with the Hat Creek 85-foot
telescope between 1968 and 1970. The individual spectra were obtained
with a bank of 100 filters covering the velocity range from -92km/s to
+75km/s. The velocity resolution was 2 km/sec (except at the ends of
the spectra) and the beamwidth was 36arcmin. The spacing between
points observed on the sky is (0.3deg/cosb) in Galactic longitude and
(0.6deg) in Galactic latitude.
A FITS version of the survey was derived at the Astrophysics Data
Facility (NASA/GSFC) from the original catalog of spectra. The
approximately 130,000 good spectra in the catalog (i.e., those with
status code 1 and which have flat baselines) were interpolated to a
uniform channel width in frequency, shifted as appropriate to take
into account the proper central velocities, then interpolated onto a
regular grid in Galactic coordinates. For the latter interpolation,
the cos(b) corrections for longitude offsets were taken into account;
no interpolation was done across gaps in coverage greater than 2 deg.
Latitude-velocity slices were written in FITS format for each 30
arcmin of longitude. Separate files were written for the negative
latitude (b < -10 deg ) and positive latitude (b > 10 deg) ranges.
Slices containing no spectra, primarily negative latitude spectra in
the fourth Galactic quadrant, were not written. A longitude-latitude
map, integrated over all velocities, was also written in FITS format
to illustrate the coverage of the individual latitude-velocity slices.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 643 134932 Northern sky survey data
software.for 80 459 Two Fortran main codes and several subroutines
lbmap.fit 2880 183 Velocity-integrated map of the whole plane
fits.dat 20 1177 Summary of velocity/latitude maps
fits/* . 1177 FITS maps of velocity/latitude
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Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 6 I6 0.001deg mGLON Galactic longitude in units of milli-degrees
7- 12 I6 0.001deg mGLAT Galactic latitude in units of milli-degrees
13- 14 I2 h RAh Right ascension (B1950)
15- 16 I2 min RAm RA in minutes
17- 18 I2 s RAs [0,60] RA in seconds
19 A1 --- DE- Sign of Declination
20- 21 I2 deg DEd Declination in degrees (B1950)
22- 23 I2 arcmin DEm DEC in arcminutes
24- 25 I2 arcsec DEs DEC in arcseconds
26- 27 I2 yr Obs.Y *Date in year
28- 29 I2 --- Obs.M *Date in month
30- 31 I2 d Obs.D *Date in day
32- 36 I5 s LST Local Standard Time
37- 41 I5 m/s cVel Central velocity (Local Standard of Rest)
42 I1 --- Status *Status Code
44-643 100I6 0.01K TA *100 antenna temperature of 6 bytes each
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Note on Obs.Y, Obs.M, Obs.D:
date = real(Obs.Y) + real(Obs.M-1)/12. + real(Obs.D-1)/(30.6*12.)
Note on Status:
The status code included in each spectrum reports the quality of the
baseline and the position transcribed to the original tape. If the
status word is 1 or 7, the profile should be perfectly good. If the
status code is 5 or 8, the profile may be good for some purposes.
Status Number of
code Spectra meaning
------- --------- -------------------------------------------
1 133095 good spectrum
4 322 bad spectrum
5 887 galactic longitude may not be as intended
6 277 position may not be as intended
7 103 calibration missing for this profile
8 176 baseline is not good
9 72 both 5 and 6 apply
------- --------- -------------------------------------------
Note on TA:
Most of the filters have a width of 10kHz, corresponding to a velocity
width of 2.11km/s; they were overlapped by half of their width. The
first 8 and last 5 filters are 30kHz wide, corresponding to 6.33km/s.
The central velocities of each channel are:
----------------------------------------
Chan. Vel. Width Chan. Vel. Width
----------------------------------------
1 -90.76 6.33 52 0.00 2.11
2 -84.43 6.33 53 1.06 2.11
3 -78.10 6.33 54 2.11 2.11
4 -71.76 6.33 55 3.17 2.11
5 -65.43 6.33 56 4.22 2.11
6 -59.10 6.33 57 5.28 2.11
7 -52.77 6.33 58 6.33 2.11
8 -46.44 6.33 59 7.39 2.11
9 -45.38 2.11 60 8.44 2.11
10 -44.32 2.11 61 9.50 2.11
11 -43.27 2.11 62 10.55 2.11
12 -42.21 2.11 63 11.61 2.11
13 -41.16 2.11 64 12.66 2.11
14 -40.10 2.11 65 13.72 2.11
15 -39.05 2.11 66 14.77 2.11
16 -37.99 2.11 67 15.83 2.11
17 -36.94 2.11 68 16.89 2.11
18 -35.88 2.11 69 17.94 2.11
19 -34.83 2.11 70 19.00 2.11
20 -33.77 2.11 71 20.05 2.11
21 -32.72 2.11 72 21.11 2.11
22 -31.66 2.11 73 22.16 2.11
23 -30.60 2.11 74 23.22 2.11
24 -29.55 2.11 75 24.27 2.11
25 -28.49 2.11 76 25.33 2.11
26 -27.44 2.11 77 26.38 2.11
27 -26.38 2.11 78 27.44 2.11
28 -25.33 2.11 79 28.49 2.11
29 -24.27 2.11 80 29.55 2.11
30 -23.22 2.11 81 30.60 2.11
31 -22.16 2.11 82 31.66 2.11
32 -21.11 2.11 83 32.72 2.11
33 -20.05 2.11 84 33.77 2.11
34 -19.00 2.11 85 34.83 2.11
35 -17.94 2.11 86 35.88 2.11
36 -16.89 2.11 87 36.94 2.11
37 -15.83 2.11 88 37.99 2.11
38 -14.77 2.11 89 39.05 2.11
39 -13.72 2.11 90 40.10 2.11
40 -12.66 2.11 91 41.16 2.11
41 -11.61 2.11 92 42.21 2.11
42 -10.55 2.11 93 43.27 2.11
43 -9.50 2.11 94 44.32 2.11
44 -8.44 2.11 95 45.38 2.11
45 -7.39 2.11 96 46.43 6.33
46 -6.33 2.11 97 52.76 6.33
47 -5.28 2.11 98 59.09 6.33
48 -4.22 2.11 99 65.43 6.33
49 -3.17 2.11 100 71.76 6.33
50 -2.11 2.11
51 -1.06 2.11
----------------------------------------
Note that these values pertain to spectra with zero central velocity.
Some spectra have a central velocity of -8440 m/s, corresponding to a
4-channel shift in the table; thus channel 56 will contain the VLSR=0
filter in these cases.
The VLSRs of each channel can also be computed by the following
FORTRAN statements:
cvelk = cVel * 0.001 ! in units of km/s
vwide = (30.e3/1420.4058e6)*2.998e5
vnarr = (10.e3/1420.4058e6)*2.998e5
do i = 1,8
VLSR(i) = real(i-1)*vwide - 90.76 + cvelk
enddo
do i = 9,95
VLSR(i) = real(i-9)*vnarr/2. - 45.38 + cvelk
enddo
do i = 96,100
VLSR(i) = real(i-96)*vwide + 46.43 + cvelk
enddo
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Byte-by-byte Description of file: fits.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- FITSfile Name of FITS file, in "fits" subdirectory
14 A1 --- NS [NS] Galactic hemisphere (N=10..90, S=-90..-10)
16- 20 F5.1 deg GaLon Galactic longitude of map
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Brief description of software.for:
FORTRAN codes for use in extracting spectra from the H I surveys of
Heiles and Habing (this catalog), Parkes (VIII/8), Argentina (VIII/9),
Bell Labs (VIII/10), and Weaver and Williams (VIII/11)
Acknowledgements:
The General Information on High-latitude 21-cm Line Surveys by
Carl Heiles (1988), University of California, Berkeley was used
in creating this ReadMe file.
History:
* The catalog was received at ADC in 1992; a brief introduction
was added at CDS (Francois Ochsenbein).
* The FITS files were created by Seth Digel in March 1997 (ADC)
* The FITS files were moved to a subdirectory, the file fits.dat
was added, and the ReadMe file was revised in November 2003 at CDS.
References:
Heiles, C. 1974, Astron. & Astrophys. Suppl. 14, 557
(End) Seth Digel & C.-H. Joseph Lyu [Hughes STX/NASA] 18-Mar-1997