iraf.net

Hello everyone!
I was using spectool and task continuum itself for fitting of spectrum continua. I had a good and robust result with 32 bit iraf v2.14. Now I have two different installations of IRAF (macintel and linux 64) and both of them show different results even when all task's parameters are exactly the same.It is very strange that in the case of 64 bit linux and macintel machines I get different result of fitting. All settings were exactly the same as in correct image (IRAF v2.14.1). I suppose that the problem is in incorrect work task sfit with (some kind of?) FITS spectra on machine with 64 bit architecture. For this reason I put here complete record of FITS header.[quote:3f1833fbe5]SIMPLE = T / Standard FITS format: NOST 100-2.0
BITPIX = -32 / No. of bits per pixel
NAXIS = 1 / No. of axes in image
NAXIS1 = 4592 / No. of pixels
EXTEND = T / FITS extension may be present
COMMENT NOST 100-2.0: Hanisch,R. et al. 2001, Astron. & Astrophys. 376, 559


CRPIX1 = 1. / Reference pixel
CRVAL1 = 4427.54980469 / Coordinate at reference pixel
CDELT1 = 0.121569000185 / Coord. incr. per pixel (original value)
CTYPE1 = ' ' / Units of coordinate
BUNIT = 'FLUX ' / Units of data values
DATAMAX = 41945.7265625 / Maximum data value
DATAMIN = 0. / Minimum data value

ORIGIN = 'ESO-MIDAS' / Written by MIDAS
DATE = '2013-04-04T13:35:07' / [UTC] Date of writing
FILENAME= 'vo040bt_1.bdf' / Original file base-name
MIDASFTP= 'IMAGE ' / MIDAS File Type

OBJECT = 'image built from polygon' / MIDAS desc.: IDENT(1)
HISTORY CREATE/IMAGE vo040bt_1 = tmpslic_out0001.bdf poly NODATA R \
HISTORY COMPUTE/IMAG vo040bt_1 = vo040bt_1+tmpslic_out0001 \
HISTORY COMPUTE/IMAG vo040bt_1 = vo040bt_1+tmpslic_out0002 \
HISTORY COMPUTE/IMAG vo040bt_1 = vo040bt_1+tmpslic_o\
HISTORY ut0003 COMPUTE/IMAG vo040bt_1 = vo040bt_1+\
HISTORY tmpslic_out0004 COMPUTE/IMAG vo040bt_1 = v\
HISTORY o040bt_1+tmpslic_out0005 COMPUTE/IMAG vo04\
HISTORY 0bt_1 = vo040bt_1+tmpslic_out0006 COMPUTE/\
HISTORY IMAG vo040bt_1 = vo040bt_1+tmpslic_out0007 \
HISTORY

HISTORY ESO-DESCRIPTORS START ................
HISTORY 'LHCUTS','R*4',1,4,'5E14.7'
HISTORY 0.0000000E+00 0.0000000E+00 0.0000000E+00 4.1945727E+04
HISTORY
HISTORY ESO-DESCRIPTORS END ................

END [/quote:3f1833fbe5]I need your help in resolving of this problem. Thanks in advance.

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Cheers, Eugene.

A quick reply without looking at your data just yet: I think the answer is explained in Buglog 575, specifically[quote:6edc0a1869]
NUMBER: 575
MODULE: all tasks using the icfit tools
SYSTEM: - V2.14
DATE: Mon Jun 28 14:08:48 MST 2010
FROM: valdesBUG: The icfit tools are used in many tasks involving 1D function fitting.
These include onedspec tasks like continuum and identify. The
tools provide for a grow radius where any sigma rejected points
have neighbors also rejected. The logic was wrong
in two ways; one where if a neighbor was also a rejected point
it did not also reject neighbors of that point, and another where
the grow radius units were used both as in pixels and in user
coordinates. In reality the grow is supposed to be in user
coordinate units. In addition some tasks, like continuum, incorrectly
described the units adding to the confusion.STATUS: Fixed for the next IRAF release.
[/quote:6edc0a1869]So the difference you see is in the behavior of the 'grow' parameter between the two versions, indeed if you set grow=0 then you get the same results in both versions. Since the v2.16 change is a fix so the code behaves correctly then this is the version you should use.Post back if this doesn't explain what you're seeing.

Hi Mike,You was completely right. The problem is in grow radius from old version of IRAF. Thanks again.

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Cheers, Eugene.