World coordinate system keywords for FITS files from Lick Observatory
Every bit of metadata added at the time of acquisition increases the
value of image data, facilitates automated processing of those data,
and decreases the effort required during subsequent data curation
In 2002 the FITS community completed a standard for World Coordinate
System (WCS) information which describes the celestial coordinates of
pixels in astronomical image data.
Most of the instruments in use at Lick Observatory and Keck Observatory
predate this standard.
None of them was designed to produce FITS files with celestial WCS information.
We report on the status of WCS keywords in the FITS files of
various astronomical detectors at Lick and Keck.
These keywords combine the information from sources which include the
telescope pointing system, the optics of the telescope and instrument,
a description of the pixel layout of the detector focal plane, and the
hardware and software mappings between the silicon pixels of the
detector and the pixels in the data array of the FITS file.
The existing WCS keywords include coordinates which refer to the
detector structure itself (for locating defects and artifacts), but
not celestial coordinates.
We also present proof-of-concept from the first data acquisition
system at Lick Observatory which inserts the WCS keywords for a
celestial coordinate system.
This paper was published in SPIE Proceedings Vol. 7740