Telescope-Control D-task DITS Parameters.

1. General: The parameters should be considered read-only; in some cases, the D-task uses parameters as read-write storage, so setting them externally would cause undefined behaviour.

2. Scalar parameters:

        Parameter       Type            Default         Description
        STATION         string          UNKNOWN         CASS or PRIME
        TELESCOPE       string          TEL             JKT, INT or WHT
        TUBE            double          1.0             temperature in Celsius
   

   the following don't serve any purpose in the DRAMA-based system, but the Perkin Elmer is likely to send the values over the IPL:

        TVPC_X          double          0.0             TV probe pos requested by
                                                        old Grinnell system
        TVPC_Y          double          0.0             ditto
        GDPC_X          double          0.0             Guide Probe pos requested
                                                        by old autoguider system
        GDPC_Y          double          0.0             ditto
        FIOF_X          double          0.0             Finder offset requested by
                                                        old autoguider system
        FIFO_Y          double          0.0             ditto.
   

3. Structured parameters:

       POSITION         tcsTrack_t      -
         double mjd;        /* Modified Julian date (days).      */
         double last;       /* Local Apparent Sideral Time (rad).*/
         double ra;         /* RA being tracked (radians).       */
         double dec;        /* Dec. being tracked (radians).     */
         double equinox;    /* Equinox of position (years).      */
         char   coordType;  /* Coord. system ('B', 'J' or 'A').  */
         double alt;        /* Altitude of Telescope (radians).  */
         double altErr;     /* Error in altitude (radians).      */
         double az;         /* Azimuth of telescope (radians).   */
         double azErr;      /* Error in azimuth (radians).       */
         double rot;        /* Position angle of rotator (rad).  */
         double roterr;
         double parallactic;/* Parallactic angle (radians).      */
         double focus;      /* Telescope focus (mm).             */
         double azDome;     /* Azimuth of dome aperture (rad).   */
         double airMass;    /* Air mass (dimensionless).         */
         double xApOff;     /* Apperture offset in x (rad).      */
         double yApOff;     /* Apperture offset in y (rad).      */
         double raOff;      /* Positional offset in RA (rad).    */
         double decOff;     /* Positional offset in Dec. (rad).  */
         double skyPa;      /* Rotator sky-position-angle (rad). */
         char   rotMode;    /* Code for rotator mode.            */
         double guideX;     /* Guiding point in x (A/G pixels).  */
         double guideY;     /* Guiding point in y (A/G pixels).  */
         char   guiMode;    /* Guiding mode.                     */
         int    vignette;   /* True when beam is vignetted.      */
         char   telstat[21];/* Tracking/moving status            */
   

   Notes:
   Parameter ranges are mostly obvious, or depend on hardware; eg 0 <= RA <= 2PI, airmass >= 1.0. telstat: "STOPPED", "FAST", "SLOW", "TRACKING"

   
        TARGET           tcsTarget_t
         char     name[21]; /* Name of object.                   */
         double   ra;       /* Right Ascension (radians).        */
         double   dec;      /* Declination (radians).            */
         double   diffRa;   /* Diff. track, RA  (radians/day).   */
         double   diffDec;  /* Diff. track, Dec (radians/day).   */
         double   equinox;  /* Equinox of position (years).      */
         double   properRa; /* Proper motion, RA (radians/year). */
         double   properDec;/* Proper motion, Dec (radians/year).*/
         double   epoch;    /* Epoch for proper motions (years). */
         double   parallax; /* Annual parallax (arcsec).         */
         double   radVel;   /* Radial velocity (km/s).           */
         char     coordType;/* Coord. system ('B', 'J' or 'A').  */
   

   Notes:
   TARGET is only valid if the telescope is driven from the DRAMA side; if the TO slews the telescope from the Perkin Elmer the target information is not available. This should go away with the VMS TCS system in which DRAMA will be much more tightly bound.