CONTAMCHK

Name

contamchk

Purpose

Check solar system object for contamination from field star.

Description

Checks against the UNSO A2.0 catalog for appulse distances with field
stars. Motion of the object is assumed to be linear over the requested
time range. Usually, the time ranges are small (on the order of an hour
or so). If a star brighter than the threshold is present within the
minimum separation distance during the time window, then the contamination
flag is set.

Calling Sequence

bad = contamchk(jd1,jd2,object,septhresh)

Inputs

jd1 - Julian date of starting time of window
jd2 - Julian date of ending time of window
object - Ephem code for solar system object
septhresh - Separation threshold (arcsec), closer than this is considered
to be contamination if star is brighter than magthresh.

Optional Input Parameters

Keyword Input Parameters

OBSCODE - Observatory code (default=500, geocentric)
MAGTHRESH - Threshold magnitude (default=20), anything fainter is ignored.
STARFILE - If provided, the USNO sub-catalog file is created and then not
deleted at the end. If the file already exists and the
name is provided, then the file is used without calling
refnet again.

Outputs

return value is a flag, if set means there is a star too close in the window.

Keyword Output Parameters

ERROR - Set on return to indicate an error condition (usually this is
cause by a bad object code).

Common Blocks

Side Effects

Restrictions

Note that if you use the starfile keyword to save the sub-catalog, it is
up to you to get rid of the file when it is no longer relevant. The saved
file will usually be no good if the date changes much or if you need to
change the magthresh to a fainter limit. This option can, if used
properly, help speed things up but the calling program must take on more
responsibility to get the right answer.

Procedure

Modification History

Written by Marc W. Buie, Lowell Observatory, 2002/03/10
2002/09/09, MWB, added support for string obscode values