Station Catalog and Locations Catalog

SCHED  uses a catalog to get station information such as names, positions, horizons, slew characteristics and more. This catalog is in keyin format. Station positions may be stored separately in a Locations Catalog. There are standard Station and Location Catalogs which will almost certainly have all stations used by a project. SCHED  will find these catalogs by default or their locations may be specified. Any or all of the Station Catalog entries may be given in the main SCHED input if desired. In any case, the scheduler should consult the catalog to be sure that the right station names are being used in the schedule. The catalog associated with this release of SCHED  is at $SCHED/catalogs/stations.dat.

SCHED  input parameter STAFILE is used to point to any desired external catalog. A file name of up to 80 characters can be specified. The default is the standard catalog:
STAFILE=$SCHED/catalogs/stations.dat

Station catalog information can be given in the main SCHED  keyin file. If the keyword STACAT appears, all input after the next ``/'' is assumed to consist of station catalog entries until a line containing the keyword ENDCAT and a ``/'' is encountered (don't combine this keyword with a catalog entry). Such ``in-line'' catalogs must appear in the SCHED  keyin file before the all of the input for the first scan is complete. This allows the use of station codes to specify stations in each scan.

Both in-line catalog entries and an external catalog may be used for the station catalog. This would mainly be useful if there is a non-standard antenna in the schedule. That antenna's parameters can be put in the in-line catalog while all other antennas are picked up from the external catalog. If you wish to prevent SCHED  from looking in external catalogs, specify STAFILE=NONE.

It is only necessary to give one of X, Y, and Z or ELev, LAT, and LONG. The missing set will be calculated. If both are given, the provided values will be used. If a conversion is done, the WGS84 ellipsoid is used and the calculations are accurate at the cm level. Since WGS84 is tied to the ITRF, this should be a good way to convert GPS coordinates to the Earth centered coordinates used in VLBI.

Some of the information that can be given in the station catalog can also be provided through a locations catalog. This is mostly position information. The locations catalog can be specified by LOCFILE. SCHED  will read and store the locations catalog before reading the stations catalog. If the station position is missing from the stations catalog, SCHED  will search for a station in the locations catalog with the name specified with DBNAME in the stations catalog. If a match is found, the associated coordinates will be used. The locations catalog is used because, in the standard catalogs, the station locations are from the VLBA correlator data base while all the other information is from other places. It is much easier to maintain separate catalogs. Users will probably not need to worry about all this, except perhaps to specify LOCFILE if they keep the SCHED  standard catalogs in a non-standard place.

The parameters of the station catalog are given below. Items that can be in the locations catalog are noted. Lower case letters are optional. Entries for a station in the Station Catalog are terminated with a ``/''.

STAtion:

Station name. Up to 8 characters.

STCode:

Station code. Up to 3 characters. Usually there are 2 characters. See Appendix A.4 for a list of codes.

DBNAME:

The station name used in the VLBA correlator data base. Might not be the same as STAtion. DBNAME is used to associate entries in the locations catalog with station catalog entries. SCHED  uses STAtion for almost everything else. This name distinguishes each pad of the interferometers. There is a matching parameter with the same name in the locations catalog. Up to 10 characters.

DBCODE:

The station code used in the VLBA correlator data base. May not be the same as STCode. SCHED  uses STCode for almost everything. This code distinguishes each pad of the intererometers so contains more information than the usual 2 letter codes given in STCode. Can be put in the locations catalog.

FRAME:

A character string indicating the origin of the station location information. Can be put in the locations catalog.

CONtrol:

Telescope control file type. Valid options are VLBA for VLBA control files, VEX for Mark IV stations and any other stations with that understand the VEX format, SNAP for most stations (Mark II only -- does not handle Mark III or Mark IV), NRAO for 140-ft type control files, VLA for VLA observe files, VSOP for VSOP type DRUDG files (Japanese version only), and NONE for no control file - the default. A V in the 5th character will cause a VLBA control file to be produced without non-DAS (Data Aquisition System -- BBC's, formatter, tape recorder etc) to be produced. If the first 4 characters were VLBA, this will be the only file. If they were something else, both the other type of file and the reduced VLBA file will be produced. This is the default when CONTROL = VLA. Option SN50 is also available for snap files with forced B1950 coordinates. The VEX option for even one station triggers production of a VEX format .skd file (once this software is ready) for all stations in addition to any antenna specific files requested.

DAR:

Gives the type of Data Aquisition Rack present. This is mainly to identify the type of formatter is at the station which will let the program know about the capabilities available. Valid types are: VLBA, MKIV, VLBA4, MKIII, S2, K4, VSOP and NONE (the default). Note that for Mark II scheduling (basically obsolete), any site scheduled will be assumed to have Mark II equipment. The main non-obvious option above is VLBA4, which is a VLBA DAR but with a Mark IV formatter installed. This will have VLBA BBC's and IF switching, but Mark IV formatting characteristics.

RECORDER:

Gives the type of tape recorder(s) present Valid options are: VLBA, MKIV, VLBA4, MKIII, S2, K4, VSOP, and NONE (the default). The VLBA4 option is for VLBA recorders which have been modified for 16 Mbps per track operation and can be equiped with 2 recording heads. They are usually associated with MKIV or VLBA4 DARs.

NBBC:

Tells SCHED  how many BBC's or VC's are at the site.

NDRIVES:

Gives the number of tape drives at the sites. Most have only 1 but all VLBA sites, for example, have 2. This can be overridden for a schedule using the NDRIVES parameter in the tape initialization information.

NHEADS:

Gives the number of recording head blocks on each VLBA or MKIV drive. This will be useful mainly for MKIV (and VLBA4) which will at some point have 2.

DISK:

Used to indicate that a disk based recording system is available at the station. Which system to use depends on the value of the MEDIA parameter in the tape initialization information. For VLBA systems, commands for both RECORDER and DISK can be included in the control file. Valid arguments to DISK for now are restricted to MARK5A and NONE (the default). MARK5B will be valid later.

MEDIADEF:

Gives the default recording system to use. It can be overridden by MEDIA in the TAPEINI section. The options are TAPE and DISK. This is meant to facilitate VLBA operations during the transition from tape to disk.

ELev:

Station elevation in meters above (mean?) sea level for geodetic coordinates or meters from the center of the Earth for geocentric coordinates; these cases are distinguished by value magnitude.

LAT:

Station latitude, either geodetic or geocentric. The format is dd:mm:ss. Positive in Northern Hemisphere.

LONG:

Station longitude, either geodetic or geocentric. The format is ddd:mm:ss. Positive in Western Hemisphere.

ZALim:

Zenith angle limit in degrees. Can be used to limit elevation coverage for stations with other than AZEL mounts. The antenna will be assumed to point below this limit to whatever limits are specified with AX1LIM and AX2LIM for purposes of slew calculations. However, if the antenna is below this limit, the source will be considered to be down during any optimizations.

X:

Station X coordinate in meters. This is in the direction of the Greenwich meridian. Can be put in the locations catalog.

Y:

Station Y coordinate in meters. This makes a right handed coordinate system with X and Z. Can be put in the locations catalog.

Z:

Station Z coordinate in meters. This is in the direction of the north pole. Can be put in the locations catalog.

DXDT:

Station rate of change of the X coordinate in meters per year. Not used in SCHED. Can be put in the locations catalog.

DYDT:

Station rate of change of the Y coordinate in meters per year. Not used in SCHED. Can be put in the locations catalog.

DZDT:

Station rate of change of the Z coordinate in meters per year. Not used in SCHED. Can be put in the locations catalog.

EPOCH:

The epoch in MJD at which the X, Y, Z coordinates apply. In other words, when the offsets due to the rates is zero. Not used by SCHED. Can be put in the locations catalog.

DEScrip:

Any text up to 80 characters (not used by SCHED).

NDRIVES:

Number of wide band tape recorders at each site. This should be the maximum number of drives at the station. If less are in service, the tape initialization input, NDRIVES can be used to sepcify the smaller number. For S2 sites, NDRIVES should be the number of individual recorders.

HOR_AZ:

Up to 200 azimuths at which horizon elevations are given in HOR_EL.

HOR_EL:

Up to 200 elevations for the horizon at the azimuths specified by HOR_AZ. SCHED's down, rise, and set notes will take these horizons into account. They will also be used in the optimization mode.

MOUNT:

The type of mount. SCHED  uses this, along with the axis limits and rates, to calculate slew times. The understood options are ALTAZ, EQUAT, XYEW and XYNS. Note that XYNS is for an XY axis system with the fixed axis in the north-south direction (for example, Fairbanks). XYEW is for the other orientation (for example, Hobart).

AXISTYPE:

The axis type as recorded in the VLBA correlator data base. Not used by SCHED. There are different keywords here than for MOUNT. Some day this should be cleaned up. Can be put in the locations catalog.

AXISOFF:

The axis offset in meters. Not used by SCHED. Can be put in the locations catalog.

AX1LIM:

The slew limits for the first axis which is usually azimuth, hour angle or X. The units are degrees for azimuth or X and hours for equatatorial mounts. There are up to 3 pairs of numbers giving the lower and upper limits for 3 different parts of the sky. This is required to describe the limits for the 140' at Green Bank and for XY antennas such as Hobart. Only the first set will be used for altaz antennas. For altaz antennas, the zero for azimuth is to the north and positive is clockwise looking down on the antenna. For XY antennas, positive is to the north or east.

AX2LIM:

The slew limits for the second axis which is usually elevation, declination, or Y. The units are degrees in all cases. There are 3 pairs of numbers which define the three parts of the sky over which the 3 pairs of AX1LIMs apply. The ranges for altaz antennas should not overlap, although they can touch. For XY antennas, overlaps are ok.

AX1RATE:

The slew rate for the first axis in degrees per minute for all mount types.

AX2RATE:

The slew rate for the second axis in degrees per minute.

AX1ACC:

The acceleration for the first axis in degrees per second squared for all mount types.

AX2ACC:

The acceleration for the second axis in degrees per second squared.

TSETTLE:

The time in seconds (or mm:ss etc) to add to the slew time for dwell time scheduling to determine when the antenna is ready to observe. This will include any computer overhead, and time to make calibration observations. Acceleration and deceleration will be calculated explicitly if the above acceleration parameters are provided in the station catalog.

MINSETUP:

The minimum interval between scans when using dwell time scheduling. If the slew time plus the settling time drops below MINSETUP, MINSETUP will be used as the interval between scans. This is required because some antennas have a minimum scan setup time but the actions that take that time can overlap with the slew. When the slew is long, the extra time does not need to be added.

MAXSRCHR:

The maximum number of sources per hour. This is originally intended to enable enforcement of the limit in the number of slews per hour on the Mark1 telescope at Jodrell. They are very worried about fatigue and will refuse to run fast switching schedules. The default is 1.E6 which should be more than anyone would try to schedule.

Below is a sample segment of the standard station catalog.

  STATION=VLBA_MK   STCODE=Mk  CONTROL=VLBA
    ELEV=3720.00  LONG=155:27:28.95    LAT=19:48:15.85
    MOUNT=ALTAZ  AX1LIM=-90,450 AX2LIM=2.25,90
    AX1RATE=90 AX2RATE=30
    TSETTLE=2  DAR=VLBA  RECORDER=VLBA  NDRIVES=2  NHEADS=1 NBBC=8
    ! MK    From 150 K Ts line by Beasley and Medcalf  Aug 1992.
    HOR_AZ =   0,  5, 10, 15, 20,120,125,130,135,140,145,150,155,160,
             165,170,175,185,190,195,200,205,210,215,220,255,260,270,
             275,280,285,290,295,300,305,310,315,320,325,330,335,340,
             345,350,355,360
    HOR_EL =   5,  4,  3,  3,  2,  2,  4,  5,  5,  4,  4,  6,  8,  8,
              11, 12, 13, 13, 11, 11,  9,  7,  5,  3,  2,  2,  3,  3,
               5,  6,  8, 10, 12, 14, 12, 11,  9, 10, 11, 10, 12, 14,
              12,  9,  7,  5
  /
  STATION=VLBA_HN   STCODE=Hn  CONTROL=VLBA
    ELEV=309.00  LONG=071:59:11.69    LAT=42:56:00.96
    MOUNT=ALTAZ  AX1LIM=-90,450 AX2LIM=2.25,90 AX1RATE=90 AX2RATE=30
    TSETTLE=2  DAR=VLBA  RECORDER=VLBA  NDRIVES=2  NHEADS=1 NBBC=8
    ! HN    From 150 K Ts line by Beasley and Medcalf  Aug 1992.
    HOR_AZ =   0,  5, 30, 35, 40, 45, 65, 70, 80, 85, 90, 95,100,105,
             110,115,120,125,130,135,140,145,150,155,160,165,170,190,
             195,200,205,210,220,225,230,235,240,245,250,255,270,275,
             290,295,315,320,325,330,335,345,350,355,360
    HOR_EL =   6,  6,  6,  4,  5,  4,  4,  5,  5,  4,  5,  4,  4,  5,
               3,  4,  4,  5,  4,  6,  5,  7,  7,  5,  3,  5,  4,  4,
               2,  5,  5,  6,  6,  5,  6,  4,  5,  5,  4,  5,  5,  4,
               4,  5,  5,  6,  5,  5,  6,  6,  5,  5,  6
 /
!   Some stations with VLBA terminals and control computers:
!   See other entries if Mark~III versions are desired.
  STATION=EB_VLBA   STCODE=Eb  CONTROL=VLBA  ZALIM=78.000
    MOUNT=ALTAZ AX1RATE=30 AX2RATE=15 AX1LIM=33,507 AX2LIM=9,89
    TSETTLE=2  DAR=VLBA  RECORDER=VLBA  NDRIVES=1  NHEADS=1 NBBC=4
    ELEV= 6365911.00  LONG=-006:53:03.98    LAT= 50:20:09.70     /

  STATION=JODRELL2   STCODE=Jb  CONTROL=SN50
    MOUNT=ALTAZ AX1RATE=22.5 AX2RATE=22.5 AX1LIM=-85,325 AX2LIM=3,89
    ELEV= 6364546.00  LONG= 002:18:24.01    LAT= 53:03:06.01
    TSETTLE=2  DAR=MKIII  RECORDER=MKIII  NDRIVES=1  NHEADS=1 NBBC=14
   /
  STATION=MEDICINA  STCODE=Mc  CONTROL=SNAP
    MOUNT=ALTAZ AX1RATE=48 AX2RATE=30 AX1LIM=90,540 AX2LIM=5,88.5
    ELEV=     100.00  LONG=-011:18:00.00    LAT= 44:30:00.00
    TSETTLE=2  DAR=MKIII  RECORDER=MKIII  NDRIVES=1  NHEADS=1 NBBC=14
   /