Preliminary specs for MOS Configuration ASCII table extension file

The MOS user provides one or more catalogs of desirable targets. The assign software applies precession, nutation, annual aberration, and refraction to the input coordinates. Sky fibers are originally specified in these coordinates before being transformed into catalog coordinates. This intermediate form of the coordinate transformation is supplied to permit post-run analysis of any modeling errors in the astrometric software.

This table will have as many rows as the input catalog(s) plus any sky fiber positions created during the assignment process. The reason for computing the positions of all objects is to permit the down-looking MOS guide camera to move and view any object in the catalog. OBJ_PKEY serves as the primary key for this table.

Keywords for coordinate systems are derived from the proposed WCS conventions and resolution R3 of the OGIP recommendations.

Detailed definitions of the FITS keywords used in this HDU are available in a data dictionary.

The Input Catalog Table FITS Header

Here follows a draft schematic for the contents of the FITS header:
XTENSION= 'TABLE   '           / ASCII table extension
BITPIX  =                    8 / number of bits per data pixel
NAXIS   =                    2 / number of data axes
NAXIS1  =                   28 / number of chars needed to describe members
NAXIS2  =                  xxx / number of objects in the catalogs
PCOUNT  =                    0 / required FITS extension keyword
GCOUNT  =                    1 / required FITS extension keyword

TFIELDS =                    6 / Number of columns in the table

EXTNAME = 'MOS_Configuration'  / This table describes MOS refracted catalogs
EXTVER  =                    1 / Unique index of this Config table in file
GRPID1  =                    1 / member of group with EXTVER=1 in same file
COMMENT   Because GRPID1 is positive we need no GRPLC1 card
DATE    = 'yyyy-mm-ddThh:mm:ss.sssZ' / Date of construction of ref catalog table

COMMENT   Keywords that describe the desired field center.
RA_PNT  =          xxx.xxxxxxx / Right Ascension of field center [degree]
DEC_PNT =          xxx.xxxxxxx / Declination of field center [degree]
HA_PNT  =          xxx.xxxxxxx / Hour Angle of field center [degree]
RADECPNT= 'FK5     '           / Coordinate system for RA_PNT and DEC_PNT
EQUINPNT=          2000.000000 / Equinox for RA_PNT and DEC_PNT [annum]
MJD_PNT =      xxxxx.xxxxxxxxx / Time of planned observation [diem]
DATE_PNT= 'yyyy-mm-ddThh:mm:ss.sssZ' / Time of planned observation

RA_3M   = 'hh:mm:ss.ssss'      / Right Ascension used to set Shane
DEC_3M  = 'sdd:mm:ss.sss'      / Declination used to set Shane
EPOCH_3M= 'Byyyy.fffff'        / Precession epoch used to set Shane
COMMENT   The coordinate system GAPPT is chosen because of the nature
COMMENT   of pointing at the Shane.  Up until 1996 the calculations for
COMMENT   precession, nutation and flexure at the Shane have been done by a
COMMENT   BASIC program on the PET computers.  This program
COMMENT   does not permit distinction of the various components of the
COMMENT   pointing model.  It seems best to do the precession, nutation,
COMMENT   and aberration to the observation epoch in code external
COMMENT   to the PET, and leave the PET to do only its flexure
COMMENT   computation.  Thus we report GAPPT coordinates for field center.

COMMENT   Various inputs to the refraction model used to produce catalog
REFWAVEL=         0.00000xxxxx / Wavelength used for refraction [m]
REFEPS  =                1.E-8 / epsilon, convergence of refraction algorithm

TELESCOP= 'Shane   '           / name of telescope
TELGLAT =          xxx.xxxxxxx / geodetic latitude of observatory [degree]
TELGLON =          xxx.xxxxxxx / geodetic longitude of observatory [degree]
TELGSYS = '1983 NAD'           / geodetic reference frame
TELHIGH =              xxxxx.x / height above sea level [m]
TELGHGT =                xxx.x / geoid height at telescope [m]
TELALAT =          xxx.xxxxxxx / astronomical latitude of observatory [degree]
TELALON =          xxx.xxxxxxx / astronomical longitude of observatory [degree]

ATMPRES =                xxx.x / Atmospheric pressure used for refraction [mbar]
ATMTEMP =                xxx.x / Ambient temperature [Kelvin]
ATMHUMID=       / Relative Humidity
ATMTTLAP=              0.0xxxx / tropospheric temperature lapse rate [Kelvin/m]

COMMENT   Various keywords describing the telescope axis misalignments
TP_ME   =              -32.449 / [arcsec]
TP_MA   =                0.000 / [arcsec]

COMMENT   Various keywords describing the tangent plane projection
ADC3MSCL=              12.3230 / [arcsec/mm]
MOSANGLE=                 0.15 / [degree]

COMMENT   Various keywords describing the radial distortion polynomial
ADCALPHA=             4.489E-7 / [mm**-2]
ADCBETA =            1.731E-12 / [mm**-4]
MOSADCX0=               6.399  / [mm]
MOSADCY0=              -0.215  / [mm]

COMMENT   Various keywords describing the polynomial warp
MOSADCA0=              116.680 / MOS-ADC Warp Coefficients A
MOSADCA1=           0.99814037 /
MOSADCA2=         -0.000684890 /
MOSADCA3=          8.29116E-09 /
MOSADCA4=          3.75417E-09 /
MOSADCA5=          3.46117E-09 /
MOSADCB0=            -145.5673 / MOS-ADC Warp Coefficients B
MOSADCB1=          0.000125097 /
MOSADCB2=           0.99944579 /
MOSADCB3=          3.11736E-09 /
MOSADCB4=          5.00529E-10 /
MOSADCB5=          7.93622E-09 /

COMMENT   Keyword describing whether or not to flop the MOS x coordinate
MOSWESTX=                    T / if true, negate the MOS x coordinate

COMMENT   Various keywords that describe coordinate system of table below
RADECSYS= 'GAPPT   '           / Coordinate system for positions in the table
MJD_WCS =      xxxxx.xxxxxxxxx / needed for GAPPT [diem]

TPRIMKEY= 'OBJ_PKEY'           / Database Primary Key
NFORKY  =                    2 / Number of foreign key joins described
TFORKY1 = 'PIVOTID'            / Foreign key
TFOREF1 = 'MOS_Hardware'       / some kind of reference to the other table
TFORKY2 = 'OBJ_PKEY'           / Foreign key
TFOREF2 = 'MOS_Input_Catalog'  / some kind of reference to the other table

TBCOL1  =                    1 / First character in column
TFORM1  = 'I6      '           / Fortran 77 format of column
TTYPE1  = 'OBJ_PKEY'           / Primary key for table of objects

TBCOL2  =                    7 / First character in column
TFORM2  = 'F11.7   '           / Fortran 77 format of column
TTYPE2  = 'HA_OBJ  '           /
TUNIT2  = 'degree  '           / Unit of measure of column

TBCOL3  =                   18 / First character in column
TFORM3  = 'F11.7   '           / Fortran 77 format of column
TTYPE3  = 'DEC_OBJ '           /
TUNIT3  = 'degree  '           / Unit of measure of column

TBCOL4  =                   29 / First character in column
TFORM4  = 'F9.6    '           / Fortran 77 format of column
TTYPE4  = 'OBJ_POSX'           /
TUNIT4  = 'meter   '           / Unit of measure of column

TBCOL5  =                   38 / First character in column
TFORM5  = 'F9.6    '           / Fortran 77 format of column
TTYPE5  = 'OBJ_POSY'           /
TUNIT5  = 'meter   '           / Unit of measure of column

TBCOL6  =                   47 / First character in column
TFORM6  = 'I3      '           / Fortran 77 format of column
TTYPE6  = 'PIVOTID '           / Key pointing into fiber table
TNULL6  = ' -1     '           / Indicates no fiber is assigned to object

The header is padded with ASCII blanks such that it consists of a positive integer multiple of 2880 bytes (36 card images of 80 characters).

The value of the keyword EXTNAME deserves further scrutiny. Other kinds of FITS groups for MOS data may become desirable; e.g., groups which relate calibration exposures to sky exposures. It may also be desirable to insert other kinds of documentary data using additional standard and/or MOS-specific keywords. The DATE keywords present an obvious problem as we enter a new century, but the FITS community has not yet developed an alternative scheme.

The MOS Configuration FITS data table

In an actual FITS data table there need be no character denoting the boundaries between the various columns. The following schematic representation of a MOS grouping table inserts the character `|' for readability. This follows the table layout given above:
     1|180.0000000| 45.0000000|-0.000xxx| 0.000yyy| -1|
     2|181.0000000| 46.0000000| 0.00xxxx| 0.0000yy| 34|
     3|179.0000000| 44.0000000| 0.0000xx|-0.00yyyy|100|
The table is padded with ASCII blanks such that it consists of a positive integer multiple of 2880 bytes.
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Steve Allen <>