[Debian-astro-maintainers] Bug#832652: scamp: queried reference catalogs of some types may have wrong sky zones

[Mo Jun]

Package: scamp
Version: 2.0.4-2+b1
Severity: normal
Tags: patch

Dear Maintainer,

1. how to reproduce this bug
  a) Find a FITS file and rename it to img.fits .
     I use a image [1] of M31 from NED in this demonstration.

  b) Run SExtractor:
   $ sextractor -d > default.sex
   $ echo -e "XWIN_IMAGE\nYWIN_IMAGE\nERRAWIN_IMAGE\nERRBWIN_IMAGE" >
scamp.param
   $ echo -e "ERRTHETAWIN_IMAGE\nFLUX_AUTO\nFLUXERR_AUTO\nFLAGS" >> scamp.param
   $ echo -e "FLAGS_WEIGHT\nFLUX_RADIUS" >> scamp.param
   $ cp /usr/share/sextractor/default.conv .
   $ sextractor -c default.sex -CATALOG_NAME img.cat \
         -PARAMETERS_NAME scamp.param -CATALOG_TYPE FITS_LDAC img.fits

  c) Run SCAMP:
   $ scamp -d > scamp.conf
   $ scamp -c scamp.conf -ASTREF_CATALOG GSC-2.3 -SAVE_REFCATALOG Y \
         -CHECKPLOT_DEV NULL -WRITE_XML N img.cat
     SCAMP can be killed when it has downloaded a reference catalog and start
   astrometric matching.

  d) Use ldactoasc to view the reference catalog:
   $ ldactoasc GSC-2.3*.cat
    The ra is from 168.25 to 168.70, and the dec is from -0.25 to 0.25, while
  the expected ra should be about 10.5 and the expected dec should be about 41.

2. which types of reference catalogs are affected
   A quick test shows GSC-2.2, GSC-2.3, NOMAD-1.0, PPMX, UCAC-2, USNO-A1.0,
 USNO-A2.0 are affected. The queried catalogs of these types are all centered
 on (ra~168.5, dec~0), expect for PPMX which is centered on (ra=0, dec=0).

   Catalogs of 2MASS, CMC-14, GSC-1.3, TYCHO-2 don't have this problem.

   Other catalogs like SDSS-R*, UCAC-3, UCAC-4 can not be downloaded.

3. patch
   After apply the attached patch, catalogs of 2MASS, CMC-14, GSC-1.3, GSC-2.2,
 GSC-2.3, NOMAD-1.0, PPMX, SDSS-R8, SDSS-R9, TYCHO-2, UCAC-2, UCAC-3,
 UCAC-4, USNO-A1.0, USNO-A2.0, USNO-B1.0 can be downloaded and all have
 right sky zone.

   Other catalog can not be downloaded which may due to they do not cover M31.
 Though I did not examine it.

   In the attched patch, the comma "," between ra and dec in the cmdline for
 curl is removed, and "%2b"(URL encoding for "+") is added when dec is large
 than 0. When catalog servers process the URL, a string ra%2bdec will converted
 to ra+dec. This may be the reason why the patch works.

   Please consider further examining this bug.

Regards,
Jun MO

[1] https://ned.ipac.caltech.edu/img/1997UITVi.U..K....C/MESSIER_031:I:V:c1997:ne.v3x300s.fits.gz

-- System Information:
Debian Release: stretch/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.6.0-1-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages scamp depends on:
ii  curl              7.47.0-1
ii  libatlas3-base    3.10.2-9+b1
ii  libc6             2.23-4
ii  libcsiro0         5.10.0+dfsg2-0.2
ii  libfftw3-single3  3.3.4-2+b1
ii  libltdl7          2.4.6-1
ii  libplplot12       5.10.0+dfsg2-0.2
ii  libqhull7         2015.2-1
ii  libqsastime0      5.10.0+dfsg2-0.2
ii  libshp2           1.3.0-8

scamp recommends no packages.

scamp suggests no packages.

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