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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
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:

       FileName      Lrecl  Records   Explanations

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/*             0     1177   FITS maps of velocity/latitude


Byte-by-byte Description of file: catalog.dat

   Bytes Format  Units     Label   Explanations

   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

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


Byte-by-byte Description of file: fits.dat

   Bytes Format Units  Label     Explanations

   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


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