NAME

regions -- Extract stars from a list of guide star regions.

USAGE

regions ra dec width mag1 mag2 exttab

DESCRIPTION

Copy guide star tables from the CD-ROM when the table overlaps a user-specified sky region. In addition to specifying a region of the sky, you can also specify a brightness range to copy only stars above or below a certain magnitude.

Note that guide star coordinates are equinox J2000.

This task will optionally plot a chart of the region with the extracted stars plotted showing their relative brightness using the task stplot.skymap. You may also draw the same plot and interact with it by running skymap independently. If you do, you must tell skymap the central coordinate, size of the field and the table column names. The center and size are the same as the parameters ra, dec, and width for regions, and the column names may be specified by setting skymap.colnames="gsc".

PARAMETERS

ra = 0. [real, min=0., max=24.]

Right ascension of the field center in hours, equinox J2000. The value may be entered on the command line or in eparam using decimal or "sexagesimal" notation, i.e., hours, minutes, and seconds with the fields separated by colons:

ra = 5:43:12.2

Missing fields are assumed to be least significant. That is, 5:43 is interpreted as 5 hours, 43 minutes rather than 0 hours, 5 minutes, 43 seconds.

dec [real, min=-90., max=90.]

Declination of the field center in degrees, equinox J2000. The value may be entered on the command line or in eparam using decimal or "sexagesimal" notation, i.e., degrees, minutes, and seconds with the fields separated by colons:

dec = -1:23:45.6

Missing fields are assumed to be least significant. That is, -1:23 is interpreted as -1 degree, 23 minutes rather than 0 hours, -1 minute, 23 seconds.

width [real, min=0., max=180.]

Field width in degrees.

exttab = extgsc [file name]

Name of the output table that will contain extracted stars.

(mag= INDEF) [real]

Lower limit of acceptable magnitudes. The default is to not use magnitude limits.

(mag= INDEF) [real]

Upper limit of acceptable magnitudes.

(allcols = no) [bool]

Copy all table columns from the GSC? If allcols=no, then only the coordinates and magnitude columns are created and written to the output table.

(savetabs = no) [bool]

Keep extracted GSC region tables? If savetabs = no, then the GSC region tables are deleted after the stars in the user's field are extracted to the output table. Otherwise, the region tables are retained in the current working directory.

(plot = no) [boolean]

Plot a sky chart of the selected region?

EXAMPLES

1. Extract a table of guide stars from a region 10 minutes wide centered at R.A. of 10 hours and Dec. of +30 degrees to a table called myregion:

  ga> regions 10 30 0:10 myregion

2. Extract and plot a region centered on 3h42m12s and -24d31'02" 15 minutes in size of stars between 11th and 14th magnitude:

  ga> regions 3:42:12 -24:31:02 0:10 myregion mag1=11 mag2=14 plot+

BUGS

SEE ALSO

strfits, extgsc, skymap

Type "help gasp opt=sys" for an overview of the gasp package and the Guide Star Catalog.