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1991ApJS...75.1011Gregory & Condon

For Users of the 87GB catalog

87GB catalog on 3.5 inch disks and FORTRAN programs to read it
The 87GB catalog (Gregory, P. C., and Condon, J. J. 1991, Ap. J. Suppl., 75, 1011) contains 54,579 sources from the Green Bank 4.85 GHz sky maps (Condon, J. J., Broderick, J. J., and Seielstad, G. A. 1989, A. J. 97, 1064) covering 6.0 sr in the declination band 0 deg to +75 deg. Two versions of this catalog are available on 3.5 inch double-sided high density (1.44 Mbyte) floppy disks --- one with equinox B1950 coordinates and sorted by increasing B1950 right ascension, the other with J2000 coordinates and sorted by increasing J2000 right ascension. Each version requires four disks. Each disk contains a directory called \87GB with six files covering 1 hr of right ascension apiece. The file names specify the equinox and hour of right ascension; e.g., the file B1950.00H covers the B1950 right ascension range from 0.0 hr up to (but not including) 1.0 hr.

Within each catalog file, there is one source per line whose format is illustrated by the first source in B1950.00H, the source 87GB 0000+1833:


 0 0 3.8 0.9 +183321 14 -42.5 106.9    70   11      1.09 0.79   9   1  939  388

The columns contain:

(01-02) Hours of right ascension, format (I2)
(03-04) Minutes of right ascension, format (I2)
(05-08) Seconds of right ascension, format (F4.1)
(10-12) RMS uncertainty in right ascension (s), format (F3.1)
(14)    Sign of declination, format (A1)
(15-16) Degrees of declination, format (I2)
(17-18) Arcminutes of declination, format (I2)
(19-20) Arcseconds of declination, format (I2)
(22-23) RMS uncertainty in declination (arcsec), format (I2)
(25-29) Galactic latitude (deg), format (F5.1)
(31-35) Galactic longitude (deg), format (F5.1)
(37-41) 4.85 GHz peak flux density (mJy), format (I5)
(43-46) RMS uncertainty in peak flux density (mJy), format (I4)
(49)    Flag "E" for significant extension, format (A1)
(50)    Flag "W" for warning, format (A1)
(51)    Flag "C" for confusion, format (A1)
(53-56) Normalized FWHM major axis, format (F4.2)
(58-61) Normalized FWHM minor axis, format (F4.2)
(63-65) Fitted major-axis position angle (deg E of N), format (I3)
(67-69) Local sky level (mJy), format (I3)
(71-74) Map pixel column number counted from left, format (I4)
(76-79) Map pixel row number counted from bottom, format (I4)
The first disk in each set of four also contains a directory called \PROGS with FORTRAN programs that can be used to read and analyze 87GB catalog data. The two programs currently in \PROGS are SELECT.FOR and MATCH.FOR. Both programs can operate on any catalog files in the same directory as their executable files, SELECT.EXE and MATCH.EXE. To run them, just type SELECT or MATCH and reply to questions appearing on your terminal.

SELECT can be used to select subsets of the 87GB catalog by right-ascension range, declination range, absolute galactic latitude range, and flux-density range. This program writes the selected sources to an output disk file with the same format as the original catalog file.

MATCH can be used to match 87GB sources with other objects by position coincidence. The object positions and position uncertainties can be entered from the terminal or from a disk file named during execution. The program assumes that this disk file gives the object positions and position uncertainties in same format as the 87GB catalog files, but it is easily modified to accept other formats (see the MATCH.FOR file). The position-coincidence criterion for a match is specified during execution by the maximum value of the parameter M, the angular separation between the object and 87GB source normalized by the quadratic sums of their rms position uncertainties (cf. Mitchell, K. J. et al. 1981, Pub. A. S. P. 93, 647). When in doubt, try setting the maximum M to about 4.0 in MATCH. Much smaller values may reject some genuine matches, and much larger values may accept too many false identifications.

J. J. Condon
Edgemont Road
Charlottesville, VA 22903
Tel: (804) 296-0322
FAX: (804) 296-0278
E-mail: jcondon@nrao