UCO/Lick Observatory built
the DEIMOS instrument
which was commissioned at Keck Observatory
in the spring of 2002.
Adapting the same technology to an older instrument, we delivered a mosaic detector for the Keck HIRES spectrograph in 2004.
Again, in 2009 we replaced the original (red) CCD for the Keck LRIS spectrograph with a mosaic detector. We also modified the LRIS blue mosaic readout to use the scheme described here.
The detectors are described above
in this web hierarchy.
Other documentary files regarding the mosaic nomenclature (images, drawings, descriptions, etc.) are visible in the panes directory.
A mosaic detector has a ``problem of numbers'' which results from the large number of identical and permutable hardware elements involved in its construction. In order to describe a mosaic, and the data produced by a mosaic, a great deal of bookkeeping information is required. In the case of the physical hardware, coaxial cables carrying video signals from one point to another can easily be permuted. It is important that the software can be reconfigured just as easily so that the resulting images will be properly documented.
The bookkeeping information for mosaics from UCO/Lick Observatory is stored in C data structures which describe mosaic layout, wiring, and configuration. At run time the data acquisition program is instructed to select one of the data structures. The data in the selected structure are inserted into the resulting FITS files in order to document which image pixels came from where, and how they go there.
The data structures which describe the mosaics were originally modelled in XML. The C data structures are isomorphic to the XML. Currently the translation between C and XML is being done manually. Eventually we hope to compile directly from the XML into C.