iraf.net

NUMBER:	239
MODULE:	onedspec tasks
SYSTEM:	V2.10 - V2.10.2
DATE:	Sat Mar  5 16:05:55 MST 1994
FROM:	valdes

BUG:    Applying IMSHIFT with a positive shift can cause errors in
	the ONEDSPEC tasks.  Negative shifts do not cause a problem.  The
	same problem has been noted previous in bug log number 180 for
	IDENTIFY and REIDENTIFY.  Errors occur when a wavelength is
	transformed to a pixel coordinate.  This happens in a number of
	operations in SPLOT.  There are various workarounds depending on
	what is desired.  A WCSRESET of the physical coordinate system can
	be used though this will cause the dispersion coordinates to also
	shift; i.e. then the shift will move the pixel relative to the
	image data array and the wavelength coordinate system.  As a
	general rule use of IMSHIFT with spectra, particularly dispersion
	calibrated spectra, should be avoided.

STATUS:	The problems have been fixed for V2.11.