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diff --git a/noao/astcat/doc/afiles.hlp b/noao/astcat/doc/afiles.hlp new file mode 100644 index 00000000..83f08791 --- /dev/null +++ b/noao/astcat/doc/afiles.hlp @@ -0,0 +1,106 @@ +.help afiles Mar00 astcat +.ih +NAME +afiles -- describe the standard astrometry files +.ih +USAGE +help files + +.ih +ASTROMETRY FILES + +An astrometry file is any text file containing celestial coordinate information +for a small region of the sky. A minimal astrometry file consists of a list +of celestial coordinate pairs one pair per line. Most astrometry files also +contain additional non- positional information, e.g. proper motions, +magnitudes, colors, etc. + +A standard astrometry file as an astrometry file containing a standard header +describing the contents and format of the file. The astcat tasks use the +header to decode the file. Normally the astrometry file header is derived +from the parent astrometric catalog description in the catalog configuration +file. If the astrometry file header is missing one may be constructed +after the fact by setting the standard field description parameter +in the \fIacatpars\fR parameter set and running the \fIafiltcat\fR task. + +A set of standard field names is reserved for describing the format of +astrometry files. The current list of standard field names is: +id, ra, dec, era, edec, pmra, pmdec, epmra, epmdec, catsystem, equinox, +epoch, px, rv, epx, erv, mag, color, emag, ecolor, xp, yp, xc, yc, exc, +eyc, imag, and eimag. For more information about these fields type +"help acatpars". + +.ih +SAMPLE STANDARD ASTROMETRY FILE + +A sample astrometry file in standard format is shown below. + +.nf +# BEGIN CATALOG HEADER +# type stext +# nheader 1 +# csystem J2000 +# nfields 4 +# ra 1 0 d hours %12.3h +# dec 2 0 d degrees %12.2h +# mag1 3 0 r INDEF %4.1f +# mag2 4 0 r INDEF %4.1f +# END CATALOG HEADER + + 00:00:01.443 -0:06:57.52 13.5 15.2 + 00:00:01.574 -0:05:33.26 16.1 18.0 + 00:00:01.904 -0:09:48.51 18.2 19.6 + 00:00:02.529 -0:04:21.53 13.4 14.4 + 00:00:04.154 -0:01:56.32 17.1 18.3 + 00:00:04.438 -0:05:00.03 11.4 13.5 + 00:00:04.697 -0:03:24.59 16.9 17.7 + 00:00:05.989 -0:02:46.36 15.1 17.6 + 00:00:07.118 -0:09:03.53 19.1 19.8 + 00:00:07.260 -0:06:47.95 17.0 17.7 + 00:00:07.314 -0:00:22.35 15.3 16.8 + 00:00:07.818 -0:02:25.90 12.2 12.4 +.fi + +.ih +SAMPLE ASTROMETRY FILE + +A sample headerless astrometry file is shown below where ra, dec, mag1 +and mag2 are stored in columns 1 through 4 respectively. + +.nf + 00:00:01.443 -0:06:57.52 13.5 15.2 + 00:00:01.574 -0:05:33.26 16.1 18.0 + 00:00:01.904 -0:09:48.51 18.2 19.6 + 00:00:02.529 -0:04:21.53 13.4 14.4 + 00:00:04.154 -0:01:56.32 17.1 18.3 + 00:00:04.438 -0:05:00.03 11.4 13.5 + 00:00:04.697 -0:03:24.59 16.9 17.7 + 00:00:05.989 -0:02:46.36 15.1 17.6 + 00:00:07.118 -0:09:03.53 19.1 19.8 + 00:00:07.260 -0:06:47.95 17.0 17.7 + 00:00:07.314 -0:00:22.35 15.3 16.8 + 00:00:07.818 -0:02:25.90 12.2 12.4 +.fi + +This file can be converted to standard form with the afiltcat task as follows + +.nf +cl> agetcat input output filter- ra="1 hours %12.3h" dec="2 degrees %12.2h" \ +mag="1-2 INDEF %4.1f" +.fi + +or by editing in a header of the form shown in the previous section. The +lines + +.nf +# BEGIN CATALOG HEADER +# END CATALOG HEADER +.fi + +delimit the header. The header must contain the type, nheader, and +nfields keyword value pairs and accurate descriptions of file the format. + +.ih +SEE ALSO +help catalogs, agetcat, afiltcat, acatpars +.endhelp |