iraf.net

NUMBER:	171
MODULE:	apextract.apfit, apextract.apflatten
SYSTEM:	V2.10.0
DATE:	Thu Jul  9 16:17:01 MST 1992
FROM:	valdes

BUG:	In these tasks which output the difference, ratio, or fit
	based on a profile model the profile model is low by a factor of
	the gain.  Thus if the gain is not one the results will not be
	correct.  For example APFLATTEN will produce flat field values
	within the aperture which are multiplied by the gain except outside
	the apertures.  The workarounds are either to use a gain of 1 or
	correct the output such as with IMARITH.  The latter option may be
	difficult to apply for APFLATTEN since special steps need to be
	taken for the interaperture values.  Note that using an gain of 1
	even though the true gain is higher will often be unimportant,
	especially if cosmic ray cleaning is not done.

STATUS:	Fixed in V2.10.1.

NUMBER:	225
MODULE:	apfit, apnormalize
SYSTEM:	V2.10 - V2.10.2
DATE:	Fri Aug 27 18:42:14 MST 1993
FROM:	valdes

BUG:	The results of the 'fit' and 'difference' in APFIT and of
	APNORMALIZE are incorrect by a factor of the gain.  This is
	basically the same bug as 171 which was not correctly fixed.
	The workarounds are to use a gain of 1.

STATUS:	Fixed in V2.10.3

NUMBER:	275
MODULE:	apnormalize
SYSTEM:	V2.10.3BETA
DATE:	Fri Jan 27 17:16:35 MST 1995
FROM:	valdes

BUG:	In bug numbers 171 and 225 it was noted that when using variance
	weighting or cleaning in APNORMALIZE the result would end up
	scaled by the gain value.  The fix was to divide the result
	by the gain.  However, the default parameters for APNORMALIZE
	do not call for variance weighting or cleaning and so the
	gain and readnoise are not read.  The uninitialized value
	of the gain used to divide the result of APNORMALIZE is
	zero causing a divide by zero error.  The workaround is
	to set the weights paraemter to 'variance'.  The actually
	weighting and gain and readnoise parameters are not important
	to this algorithm.

STATUS:	This only affects version V2.10.3BETA and will be fixed in
	later versions.