Bugs: dmcoords
Table of Contents
Caveats
dmcoords does not work correctly on the ACIS blank-sky background files
Switching between celfmt=deg and celfmt=hms can lead to a misleading error message.
Bugs
Caveats
dmcoords does not work correctly on the ACIS blank-sky background files
The pointing (PNT) header keyword values in the background files are set to zero:
unix% dmlist bgevt2_c7.fits header |grep PNT 0058 RA_PNT 0 Real8 Pointing RA 0059 DEC_PNT 0 Real8 Pointing Dec 0060 ROLL_PNT 0 [deg] Real8 Roll (fake)
These values indicate where the optical axis was during the observation. Having zero-values will cause the CIAO tool dmcoords to produce incorrect results when run with the background file.
Workaround:
Follow the workaround in the The ACIS "Blank-Sky" Background Files thread to update the PNT header keyword values.
Switching between celfmt=deg and celfmt=hms can lead to a misleading error message.
When switching between using celfmt=hms to celfmt=deg, dmcoords may already have some RA/Dec values set: ra, dec, ra_zo, dec_zo, etc. Unless these parameters are explicitly set to a blank string, the tool will complain about an "Invalid entry" and will prompt for a new value.
unix% punlearn dmcoords unix% dmcoords /export/byobsid/635/repro/acisf00635_repro_evt2.fits asol= op=sky x=4096 y=4096 unix% pget dmcoords ra dec 16:27:17.957 -24:34:24.40 unix% dmcoords /export/byobsid/635/repro/acisf00635_repro_evt2.fits asol= op=sky x=4096 y=4096 celfmt=deg Invalid entry '16:27:17.957' - try again! ra_zo[ deg ] :
Workaround:
To work around the problem, simply
% punlearn dmcoords
between uses.
Bugs
Incorrect values from CAR transform.
The WCS library that the DM uses has a problem computing coordinate transforms that involve the CAR transform.