XTENSION= 'IMAGE ' / IMAGE extension BITPIX = 16 / number of bits per data pixel NAXIS = 2 / number of data axes NAXIS1 = 708 / length of data axis 1 NAXIS2 = 568 / length of data axis 2 PCOUNT = 0 / required keyword; must = 0 GCOUNT = 1 / required keyword; must = 1Note above that BITPIX=16, which indicates that the FITS file contains big-endian signed 16-bit two's complement integers (range -32768 to +32767). It is the case for all of the UCO/Lick CCD hardware that the analog-to-digital conversion produces unsigned 16-bit integers (range 0 to 65535). The structure of two's complement arithmetic allows these data values to be written into a FITS file simply by flipping the high order (sign) bit and setting the next two FITS keywords to these values.

BZERO = 32768 / offset data range to that of unsigned short BSCALE = 1 / default scaling factorThis is the date that CFITSIO obtained by querying the system clock for the POSIX

DATE = '2004-05-20T22:22:47' / file creation date (YYYY-MM-DDThh:mm:ss UT)The CCD crates designed at Lick do not have code intended to indicate a NULL pixel value. Under normal operation the digital values from the A/D conversion are set such that they are always significantly greater than zero. That allows us to suppose that any pixel with value zero is intended to be NULL. Given the values of

BLANK = -32768 / FITS array value of NULL pixel

In order to decode the pixel stream from the mosaic detectors
designed at Lick, the `lickserv2` process uses data
structures which contain a complete description of the layout of
the various mosaics, the detectors in each mosaic, and the manner
in which the cables and electronics transfer the pixel values.
For a description see XML schema for documenting
mosaics of detectors.
The notion is that all of the metadata describing the provenance
of the data values in the pixels will be documented by FITS
keywords.

The `EXTNAME` keyword indicates the reason that this
IMAGE HDU has been included in the MEF file. In this case
the pixels originate from Video Input number 1 and they are
recorded here as a result of Pane number 1.

EXTNAME = 'VidInp1+Pane1' / name of this image extensionThe metadata about this mosaic are documented by the following keywords whose values come from the data structure. Note in particular that the

DETCNFID= 1002 / mosaic detector configuration Id DETCNFIG= 'HIRES Science mosaic' / mosaic detector configuration MOSAIC = 'HIRES Science Mosaic' / mosaic detector MOSDESIN= 'HIRES Mosaic' / mosaic detector design AMPWIRES= 'HIRES Wiring, 6-amplifier' / mosaic amplifier wiringThe following keywords are intended to give complete metadata documenting the identity of the mosaic components which produced these pixels.

VIDEOINP= 1 / see HIRES engineering drawing H9604 AMPLOC = '1 ' / see HIRES engineering drawing H9604 AMPTYPE = 'A ' / type of amplifier CCDLOC = '1 ' / see HIRES engineering drawing H9604 CCDGEOM = 'MIT/LL 2k*4k' / geometry of CCD CCDNAME = '17-7-1 ' / name of CCD CCDTYPE = 'High Resistivity' / type of CCDSome CCD controllers are able to hasten the CCD readout by reading some rows of interest, quickly skipping past other rows which are not part of any active

REXTID = 0 / row extent of this readout PANEID = 1 / PANE which inspired this HDUThere is a longstanding convention from NOAO/IRAF that sub-regions of the FITS array are described by "sections" with a Fortran-like syntax in the FITS keyword value. The most relevant of all such section keywords is

DATASEC = '[13:628,1:568]' / NOAO/IRAF data section DETSIZE = '[1:6144,1:4096]' / NOAO mosaic detector size for ds9 DETSEC = '[409:1024,712:1279]' / NOAO mosaic detector section for ds9The

The WCS which is intended to be used during most conversations about the pixels in a mosaic is the pane coordinate system. The pane coordinates are an idealized notion of the layout of the mosaic which ignores the gaps between detectors and which is independent of the binning used in any particular readout.

CRPIX1P = 13. / reference pixel along FITS axis j CRPIX2P = 1. / reference pixel along FITS axis j CRVAL1P = 408.5 / coordinate value for WCS axis i at refpix CRVAL2P = 711.5 / coordinate value for WCS axis i at refpix CD1_1P = 1. / CTM i_j from pixel to WCS CD1_2P = 0. / CTM i_j from pixel to WCS CD2_1P = 0. / CTM i_j from pixel to WCS CD2_2P = 1. / CTM i_j from pixel to WCS CTYPE1P = 'PANE_X ' / coordinate/projection type for WCS axis i CTYPE2P = 'PANE_Y ' / coordinate/projection type for WCS axis i CUNIT1P = 'pixel ' / physical unit for WCS axis i CUNIT2P = 'pixel ' / physical unit for WCS axis i WCSNAMEP= 'pane ' / UCO/Lick mosaic PANE coordinates CRDER1P = 0. / coordinate random error for WCS axis i CRDER2P = 0. / coordinate random error for WCS axis i CSYER1P = 0. / coordinate systematic error for WCS axis i CSYER2P = 0. / coordinate systematic error for WCS axis iThe amplifier coordinates are intended to indicate the coordinate of a pixel with respect to the amplifier through which its datum was read. This coordinate makes sense to specify only if the pixel values from each amplifier are stored in separate FITS IMAGE extensions.

CRPIX1A = 13. / reference pixel along FITS axis j CRPIX2A = 1. / reference pixel along FITS axis j CRVAL1A = 409. / coordinate value for WCS axis i at refpix CRVAL2A = 712. / coordinate value for WCS axis i at refpix CD1_1A = 1. / CTM i_j from pixel to WCS CD1_2A = 0. / CTM i_j from pixel to WCS CD2_1A = 0. / CTM i_j from pixel to WCS CD2_2A = 1. / CTM i_j from pixel to WCS CTYPE1A = 'AMPLIFIER_X' / coordinate/projection type for WCS axis i CTYPE2A = 'AMPLIFIER_Y' / coordinate/projection type for WCS axis i CUNIT1A = 'pixel ' / physical unit for WCS axis i CUNIT2A = 'pixel ' / physical unit for WCS axis i WCSNAMEA= 'amplifier' / imaging pixels thru this amplifier CRDER1A = 0. / coordinate random error for WCS axis i CRDER2A = 0. / coordinate random error for WCS axis i CSYER1A = 0. / coordinate systematic error for WCS axis i CSYER2A = 0. / coordinate systematic error for WCS axis iThe CCD coordinates are intended to indicate the coordinate of a pixel with respect to the silicon structure of a particular chip. The choice of coordinate origin on a chip is documented by the mosaic metadata keywords mentioned above.

CRPIX1C = 13. / reference pixel along FITS axis j CRPIX2C = 1. / reference pixel along FITS axis j CRVAL1C = 409. / coordinate value for WCS axis i at refpix CRVAL2C = 712. / coordinate value for WCS axis i at refpix CD1_1C = 1. / CTM i_j from pixel to WCS CD1_2C = 0. / CTM i_j from pixel to WCS CD2_1C = 0. / CTM i_j from pixel to WCS CD2_2C = 1. / CTM i_j from pixel to WCS CTYPE1C = 'CCD_X ' / coordinate/projection type for WCS axis i CTYPE2C = 'CCD_Y ' / coordinate/projection type for WCS axis i CUNIT1C = 'pixel ' / physical unit for WCS axis i CUNIT2C = 'pixel ' / physical unit for WCS axis i WCSNAMEC= 'ccd ' / NOAO mosaic CCD coordinates CRDER1C = 0. / coordinate random error for WCS axis i CRDER2C = 0. / coordinate random error for WCS axis i CSYER1C = 0. / coordinate systematic error for WCS axis i CSYER2C = 0. / coordinate systematic error for WCS axis iThe detector coordinates are intended to match the definition from the description of the NOAO/IRAF mosaic keywords in the documents by Frank Valdes.

CRPIX1D = 13. / reference pixel along FITS axis j CRPIX2D = 1. / reference pixel along FITS axis j CRVAL1D = 409. / coordinate value for WCS axis i at refpix CRVAL2D = 712. / coordinate value for WCS axis i at refpix CD1_1D = 1. / CTM i_j from pixel to WCS CD1_2D = 0. / CTM i_j from pixel to WCS CD2_1D = 0. / CTM i_j from pixel to WCS CD2_2D = 1. / CTM i_j from pixel to WCS CTYPE1D = 'DETECTOR_X' / coordinate/projection type for WCS axis i CTYPE2D = 'DETECTOR_Y' / coordinate/projection type for WCS axis i CUNIT1D = 'pixel ' / physical unit for WCS axis i CUNIT2D = 'pixel ' / physical unit for WCS axis i WCSNAMED= 'detector' / NOAO mosaic CCD coordinates CRDER1D = 0. / coordinate random error for WCS axis i CRDER2D = 0. / coordinate random error for WCS axis i CSYER1D = 0. / coordinate systematic error for WCS axis i CSYER2D = 0. / coordinate systematic error for WCS axis iThe image coordinates are intended to be a redundant reiteration of the Fortran-like default FITS array coordinate for the pixels.

CRPIX1I = 1. / reference pixel along FITS axis j CRPIX2I = 1. / reference pixel along FITS axis j CRVAL1I = 1. / coordinate value for WCS axis i at refpix CRVAL2I = 1. / coordinate value for WCS axis i at refpix CD1_1I = 1. / CTM i_j from pixel to WCS CD1_2I = 0. / CTM i_j from pixel to WCS CD2_1I = 0. / CTM i_j from pixel to WCS CD2_2I = 1. / CTM i_j from pixel to WCS CTYPE1I = 'IMAGE_X ' / coordinate/projection type for WCS axis i CTYPE2I = 'IMAGE_Y ' / coordinate/projection type for WCS axis i CUNIT1I = 'pixel ' / physical unit for WCS axis i CUNIT2I = 'pixel ' / physical unit for WCS axis i WCSNAMEI= 'image ' / redundant reiteration of default FITS CRDER1I = 0. / coordinate random error for WCS axis i CRDER2I = 0. / coordinate random error for WCS axis i CSYER1I = 0. / coordinate systematic error for WCS axis i CSYER2I = 0. / coordinate systematic error for WCS axis iThe primary coordinates are the same as the Pane coordinates in order to indicate that we believe this coordinate system is the best one for use in conversation.

CRPIX1 = 13. / reference pixel along FITS axis j CRPIX2 = 1. / reference pixel along FITS axis j CRVAL1 = 408.5 / coordinate value for WCS axis i at refpix CRVAL2 = 711.5 / coordinate value for WCS axis i at refpix CD1_1 = 1. / CTM i_j from pixel to WCS CD1_2 = 0. / CTM i_j from pixel to WCS CD2_1 = 0. / CTM i_j from pixel to WCS CD2_2 = 1. / CTM i_j from pixel to WCS CTYPE1 = 'PANE_X ' / coordinate/projection type for WCS axis i CTYPE2 = 'PANE_Y ' / coordinate/projection type for WCS axis i CUNIT1 = 'pixel ' / physical unit for WCS axis i CUNIT2 = 'pixel ' / physical unit for WCS axis i WCSNAME = 'pane ' / UCO/Lick mosaic PANE coordinates CRDER1 = 0. / coordinate random error for WCS axis i CRDER2 = 0. / coordinate random error for WCS axis i CSYER1 = 0. / coordinate systematic error for WCS axis i CSYER2 = 0. / coordinate systematic error for WCS axis iThe gap coordinates are intended to give a rough indication of the actual geometry of the detectors in the mosaic including the gaps between them. This allows the SAO ds9 image display to show something very close to the actual layout of the focal plane.

CRPIX1G = 13. / reference pixel along FITS axis j CRPIX2G = 1. / reference pixel along FITS axis j CRVAL1G = 409. / coordinate value for WCS axis i at refpix CRVAL2G = 712. / coordinate value for WCS axis i at refpix CD1_1G = 1. / CTM i_j from pixel to WCS CD1_2G = 0. / CTM i_j from pixel to WCS CD2_1G = 0. / CTM i_j from pixel to WCS CD2_2G = 1. / CTM i_j from pixel to WCS CTYPE1G = 'GAP_X ' / coordinate/projection type for WCS axis i CTYPE2G = 'GAP_Y ' / coordinate/projection type for WCS axis i CUNIT1G = 'pixel ' / physical unit for WCS axis i CUNIT2G = 'pixel ' / physical unit for WCS axis i WCSNAMEG= 'ccd2gap ' / approximate gap coordinates CRDER1G = 1. / coordinate random error for WCS axis i CRDER2G = 1. / coordinate random error for WCS axis i CSYER1G = 1. / coordinate systematic error for WCS axis i CSYER2G = 1. / coordinate systematic error for WCS axis iThe last thing that

CHECKSUM= 'ZSHEgR99ZRGEfR99' / HDU checksum updated 2004-05-20T22:23:22 DATASUM = '649738213' / data unit checksum updated 2004-05-20T22:23:22 END

Steve Allen <sla@ucolick.org> Initial deployment 2010-04-16

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