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extgst stsdas.gasp



extgst -- Extract rows from one or more guide star tables.


extgst intablist outable ra dec width


Select guide stars from one or more guide star tables and write them to a new STSDAS table. The user specifies a list of input table names as a file name template. The input table(s) are assumed to be output from the sgscind task, i.e., one or more STSDAS tables containing guide star regions from the CD-ROM Guide Star Catalog. The extgst task uses the specified region center and width to define a field from which to select stars from the input tables. One may also specify a pair of magnitudes; only stars within these limits are selected from the catalog. Coordinates and magnitudes of the selected stars are written to a new STSDAS table.

By default, only the coordinates and magnitudes from the GSC catalog tables are saved in the output table. The allcols paramater may be toggled to permit saving all of the columns from the GSC into the output merged table.

Note that the GSC coordinates are equinox J2000; this should also be true of the input field center. See the precess tasks to precess coordinates.

Table Columns
The columns in the GSC catalog region table are described as follows:

Column Name    Data Type   Print Format   Units
------ ----    ---- ----   ----- ------   -----
RA_HRS         Double      %11.2h         hours
RA_DEG         Double      %11.1h         degrees
DEC_DEG        Double      %11.1h         degrees
MAG            Real        %6.1f          magnitudes
GSC_ID         Integer     %5d
PLATE_ID       String      %-4s
POS_ERR        Real        %5.1f          degrees
MAG_ERR        Real        %4.2f          magnitudes
MAG_BAND       Integer     %2d
CLASS          Integer     %1d
MULTIPLE       String      %-1s

The first column, RA_HRS does not appear in the GSC tables on the CD, but is written to the output tables by extgst. It contains the same R.A. coordinates as RA_DEG, but the units are hours rather than degrees. If allcols=no, then only the first four columns are written to the output table.

See the package, the tlcol task in particular for more information regarding the attributes of table columns.


intablist [file name template]
List of input tables to search. This parameter can take a list of files (delimited by commas), wildcard characters to specify a group of files, or the name of a list file that contains the names of files to be searched.
outable [file name]
Output STSDAS table containing selected stars.
ra [real, min = 0, max = 24]
Right ascension of field center in hours, equinox J2000.
dec [real, min = -90, max = 90]
Declination of field center in degrees, equinox J2000.
width [real, min = 0, max = 180]
Width of field (in degrees).
(mag= INDEF) [real]
Upper brightness limit (in magnitude). If both mag1 and mag2 are passed INDEF values, the search will be unrestricted.
(mag= INDEF) [real]
Lower brightness limit in magnitude. If both mag1 and mag2 are passed INDEF values, the search will be unrestricted.
(onestar = yes) [boolean]
Use only one entry for a given star?
(plateid) [boolean]
Guide star plate ID. If onestar= es and plateid is specified, then use only stars from this plate.
(allcols = no) [boolean]
Use all GSC columns? If yes, copy all table columns for selected stars from the GSC catalog table(s) to the output merged table. Otherwise, copy only coordinates and brightness, the default.
(nstars = INDEF) [integer]
The number of stars selected. This is an output parameter.




regions, targets, sgscind

Type "help gasp opt=sys" for more information about using the gasp package and the Guide Star Catalog.

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