Public bug reported:
Observed using the binary sextractor package on Ubuntu hardy i386:
some columns in the object catalog end up containing only zeros, an
incorrect result for the input data supplied.
To reproduce, take a FITS file and run it through sextractor. The problem can
be reproduced using the options suggested in the man page:
sextractor file.fits -c /usr/share/sextractor/default.sex -PARAMETERS_NAME
/usr/share/sextractor/default.param -FILTER N
and look at the values for X_IMAGE and Y_IMAGE in the output file (test.cat).
Another parameter affected is ELLIPTICITY. Using a suitably modified .param
file:
# 1 X_IMAGE Object position along x [pixel]
# 2 Y_IMAGE Object position along y [pixel]
# 3 ELLIPTICITY 1 - B_IMAGE/A_IMAGE
# 4 A_IMAGE Profile RMS along major axis [pixel]
# 5 B_IMAGE Profile RMS along minor axis [pixel]
# 6 THETA_IMAGE Position angle (CCW/x) [deg]
# 7 XMIN_IMAGE Minimum x-coordinate among detected pixels [pixel]
# 8 XMAX_IMAGE Maximum x-coordinate among detected pixels [pixel]
0.000 0.000 0.000 0.912 0.674 -33.2 729 732
0.000 0.000 0.000 0.729 0.436 -71.6 608 609
0.000 0.000 0.000 0.775 0.711 35.7 812 814
[ ... and so on ]
Clearly something is wrong: 1 - 0.674/0.912 is rather different from
zero.
I was able to fix the problem simply by rebuilding the sextractor
package, *without any changes to the source*, with current hardy
compilers and build tools (I used pbuilder). My guess is that the i386
deb that is currently in the Ubuntu archive for hardy was miscompiled.
** Affects: sextractor (Ubuntu)
Importance: Undecided
Status: New
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X_IMAGE, Y_IMAGE, ELLIPTICITY are always zero
https://bugs.launchpad.net/bugs/283142
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