iraf.net

NUMBER:	214
MODULE:	scopy, sarith
SYSTEM:	V2.10-V2.10.2
DATE:	Thu May 20 17:07:53 MST 1993
FROM:	valdes

BUG:	When using SCOPY or SARITH with a specified wavelength range,
	w1 and w2 not equal to INDEF, and rebin=yes the spectra are
	correctly resampled to the requested wavelength interval but
	the coordinate system in the header is updated incorrectly.
	The coordinates may be off by a fraction of a pixel.  For
	example if w1=6400 and w2=6600 the output data will have
	the first pixel at 6400 but the coordinate reported by
	LISPIXEL or any other task might be 6400.25 (where the
	dispersion is, say, 3 Angstroms per pixel).  This error
	is caused during the conversion from logical to physical
	pixel coordinates when the physical coordinates are treated
	as integer; i.e. a wavelength of 6400 for the first logical
	pixel might be physical pixel 185.325 but it is then
	truncated to 185 and the coordinate system is set so
	that physical pixel 185 is 6400 and pixel 185.325 is
	6400.25.  This is a subtle error which may be discovered
	by looking at the coordinate of the first pixel with LISTPIX
	and comparing it with the requested wavelength of the first pixel.

STATUS:	Fixed in V2.10.3.

NUMBER:	325
MODULE:	onedspec tasks, splot
SYSTEM:	V2.10.3-V2.10.4 (before patch 1)
DATE:	Tue Jan 30 10:01:17 MST 1996
FROM:	valdes

BUG:	In V2.10.4 patch 1 the syntax for storing the coordinate system
	keywords (WAT...) was changed such that the closing quote occurs
	at the end of the string rather than the end of the card.  This
	makes the multispec format spectra incompatible with V2.10.3
	and V2.10.4 before patch1 in various tasks such as SPLOT.  The
	behavior is:

        In V2.10.3:
	  ERROR: Unknown coordinate system `multispec''
	In V2.10.4:
	  WARNING: Unknown coordinate system `multispec'' - assuming `linear'.

	In V2.10.3 this is a fatal error while in V2.10.4 this is a warning
	(however it will then not correctly interpret the coordinates).
	The workaround is to edit the image header as follows:

	    cl> hedit  wat0_001 'system=multispec x'

	The extra ' x' is needed to force a space after the system name.
	After this the data will be compatible with all V2.10 versions.

STATUS:	There is no 'fix' to this backward compatibility problem.  When
	moving to earlier versions users must apply the workaround.