During the operation of the slitmask design code the user may choose a number of ``sky slitlet'' positions which were not originally in the catalog. These sky positions are converted from their mask coordinates or refracted coordinates back to catalog positions and added to this table. This FITS table should serve as both an input and output file format for the slitmask design code.
This table should contain only information about the objects. Inclusion of other entities would denormalize the schema of the tables as a database.
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.
XTENSION= 'TABLE ' / ASCII table extension BITPIX = 8 / number of bits per data pixel NAXIS = 2 / always 2 for a FITS table NAXIS1 = xxx / 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 = 18 / Number of columns in the table EXTNAME = 'DEIMOS_Input_Catalog' / This table describes DEIMOS input 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 = 'dd/mm/yy' / Date of construction of input catalog table CTIME = 'WkD CcYy Mon Dt Hr:Mn:Ss TZn' / Time of construction of table COMMENT Various keywords specifying the desired telescope axis RA_PNT = xxx.xxxxxxx / Right Ascension of Keck II axis [degree] DEC_PNT = xxx.xxxxxxx / Declination of Keck II axis [degree] RADECPNT= 'FKx' / Coordinate system for RA_PNT and DEC_PNT EQUINPNT= xxxxxx.xxxxxx / Equinox for RA_PNT and DEC_PNT [annum] MJD_PNT = 24xxxxx.xxxxxxxxx / needed if RADECPNT is FK4 [diem] DEISKYPA= xxx.xxxxxxx / Position angle of DEIMOS on the sky CTIMEPNT= 'WkD CcYy Mon Dt Hr:Mn:Ss TZn' / Planned time of observation TBCOL1 = 1 / First character in column TFORM1 = 'A8' / Fortran 77 format of column TTYPE1 = 'SNAME' / TBCOL2 = xx / First character in column TFORM2 = 'F11.7' / Fortran 77 format of column TTYPE2 = 'RA_OBJ' / TUNIT2 = 'degree' / Unit of measure of column TBCOL3 = xx / First character in column TFORM3 = 'F11.7' / Fortran 77 format of column TTYPE3 = 'DEC_OBJ' / TUNIT3 = 'degree' / Unit of measure of column TBCOL4 = xx / First character in column TFORM4 = 'I4' / Fortran 77 format of column TTYPE4 = 'PRIO' / TBCOL5 = xx / First character in column TFORM5 = 'F7.3' / Fortran 77 format of column TTYPE5 = 'MAG' / TNULL5 = '-99.999' / Indicates data not provides in input TBCOL6 = xx / First character in column TFORM6 = 'A128' / Fortran 77 format of column TTYPE6 = 'NAME' / TBCOL7 = xx / First character in column TFORM7 = 'F13.6' / Fortran 77 format of column TTYPE7 = 'EQUINOX' / TUNIT7 = 'annum' / Unit of measure of column TBCOL8 = xx / First character in column TFORM8 = 'A128' / Fortran 77 format of column TTYPE8 = 'CAT_FILE' / TBCOL9 = xx / First character in column TFORM9 = 'I6' / Fortran 77 format of column TTYPE9 = 'OBJ_PKEY' / Primary key for table of objects TBCOL10 = xx / First character in column TFORM10 = 'A8' / Fortran 77 format of column TTYPE10 = 'RADECSYS' / TNULL10 = 'NULL ' / Indicates data not provided in input TBCOL11 = xx / First character in column TFORM11 = 'F9.4' / Fortran 77 format of column TTYPE11 = 'PM_RA' / TUNIT11 = 'arcsec/(Julian annum)' / Unit of measure of column TNULL11 = '-999.9000' / Indicates data not provided in input TBCOL12 = xx / First character in column TFORM12 = 'F9.4' / Fortran 77 format of column TTYPE12 = 'PM_DEC' / TUNIT12 = 'arcsec/(Julian annum)' / Unit of measure of column TNULL12 = '-999.9000' / Indicates data not provided in input TBCOL13 = xx / First character in column TFORM13 = 'F17.9' / Fortran 77 format of column TTYPE13 = 'MJD_WCS' / TUNIT13 = 'diem' / Unit of measure of column TNULL13 = '-999999.000000000' / Indicates data not provided in input TBCOL14 = xx / First character in column TFORM14 = 'F7.4' / Fortran 77 format of column TTYPE14 = 'PARALLAX' / TUNIT14 = 'arcsec' / Unit of measure of column TNULL14 = '-9.9999' / Indicates data not provided in input TBCOL15 = xx / First character in column TFORM15 = 'F13.3' / Fortran 77 format of column TTYPE15 = 'RAD_VEL' / TUNIT15 = 'm/s' / Unit of measure of column TNULL15 = '300000000.000' / Indicates data not provided in input TBCOL16 = xx / First character in column TFORM16 = 'F10.7' / Fortran 77 format of column TTYPE16 = 'MAJAXIS' / TUNIT16 = 'degree' / Unit of measure of column TNULL16 = '-9.9900000' / Indicates data not provided in input TBCOL17 = xx / First character in column TFORM17 = 'F10.7' / Fortran 77 format of column TTYPE17 = 'MINAXIS' / TUNIT17 = 'degree' / Unit of measure of column TNULL17 = '-9.9900000' / Indicates data not provided in input TBCOL18 = xx / First character in column TFORM18 = 'F11.7' / Fortran 77 format of column TTYPE18 = 'PA_AXIS' / this may not be the best choice of name TUNIT18 = 'degree' / Unit of measure of column TNULL18 = '-99.9000000' / Indicates data not provided in input ENDThe 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 DEIMOS 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 DEIMOS-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.
Even though many inputs catalogs will not have values for them, the inclusion of the full set of 3-d astrometric entities in this table is important. It permits the use of standardized WCS software, and encourages full understanding of coordinate system subtleties.
User catalogs will not typically originate as FITS files. There should be a tool which permits the astronomer to transform a given input catalog into this standardized DEIMOS format. In the case where the original catalog does not contain full astrometric information the translation program should prompt with reasonable default values. For objects read from such a file the table will indicate the lack of information by the use of the FITS ASCII Table TNULL conventions.