iraf.net

NUMBER:	161
MODULE:	apextract.apsum
SYSTEM:	V2.9
DATE:	Wed Oct 30 11:02:38 MST 1991
FROM:	valdes

BUG:	If the background regions go off the image, due to tilts in the
	spectrum such as with echelle data, while the object apertures
	remains on the image a segmentation violation occurs.  This will
	only happen with one-sided background regions as otherwise this
	condition could not occur.  The error is caused by a failure to
	check for an error condition from background fitting.

STATUS:	This error is fixed in V2.10.  The workaround is to insure
	at least part of the background regions are on the image while the
	object aperture is on the image.  This would be true if background
	regions are defined on both sides of the aperture.  Note that it is
	ok for the object aperture and background regions to both be off
	the the image.  The source fix is simple and could be supplied if
	absolutely necessary.