Bugs: dmcoords
Table of Contents
Caveats
Bugs
Caveats
dmcoords does not work correctly on the ACIS blank-sky background files (28 Jan 2010)
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.
Bugs
Incorrect values from CAR transform.
(08 Oct 2012)
The WCS library that the DM uses has a problem computing coordinate transforms that involve the CAR transform.
Incorrect azimuth and off-axis angle for HRC event files
A keyword was dropped when filtering columns from HRC evt2 files in the pre-CIAO 3.0 data model. This causes dmcoords to not have correct knowledge of the aspect solution; the tool therefore computes an incorrect zero point for the azimuth (phi) and off-axis angle (theta).
Workaround:
Use dmstat to get the DETX,DETY values:
unix% dmstat "evt2[sky=region(reg)][cols det]"
and then use dmcoords to convert these to theta and phi values.
Bugs fixed in CIAO 4.4
The following is a list of bugs that were fixed in the CIAO 4.4 software release.
Warning issued even when WCS matches (01 Feb 2011)
Due to a precision issue in dmcoords, a warning may be printed even if the NOM and WCS values match. As long as the reported values are the same, this warning may be ignored:
# dmcoords (CIAO): Warning: RA_NOM DEC_NOM different from WCS
# dmcoords (CIAO): RA_NOM DEC_NOM = 224.013323 -68.725752
WCS = 224.013323 -68.725752

![[CIAO Logo]](../imgs/ciao_logo_navbar.gif)