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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 $SCHED/catalogs/stations.dat.
SCHED input parameter STAFILE is used to point to any desired
external catalog. A file name of up to 80 characters can be
specified. The default is the standard catalog for digital backends:
STAFILE=$SCHED/catalogs/stations_RDBE.dat. Eventually that
will be set back to STAFILE=$SCHED/catalogs/stations.dat once
the conversion of documentation and examples is complete.
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. See the description of that parameter for a
list of the station parameter that can be in the locations catalog.
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
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
Version and station names:
- Catalog version. Actually set to the date when
all the master catalog segments were last gathered to form a full catalog.
- Station name. Up to 8 characters.
- Station code. Up to 3 characters. Usually there
are 2 characters. See Appendix A.1 for a list
- 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.
- 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
- A character string indicating the origin
of the station location information. Can be put in the locations
- 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
- Station latitude, either geodetic or geocentric.
The format is dd:mm:ss. Positive in Northern Hemisphere.
- Station longitude, either geodetic or geocentric.
The format is ddd:mm:ss. Positive in Western Hemisphere.
- 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.
- Station X coordinate in meters. This is in the
direction of the Greenwich meridian. Can be put in the locations
- Station Y coordinate in meters. This makes a right
handed coordinate system with X and Z. Can be put in the locations
- Station Z coordinate in meters. This is in the
direction of the north pole. Can be put in the locations catalog.
- Station rate of change of the X coordinate in
meters per year. Not used in SCHED. Can be put in the locations
- Station rate of change of the Y coordinate
in meters per year. Not used in SCHED. Can be put in the locations
- Station rate of change of the Z coordinate
in meters per year. Not used in SCHED. Can be put in the locations
- 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
- Any text up to 80 characters (not used
- Telescope control file type. VEX files
are produced for all projects because most antennas are converting
to using them for telescope control (including the VLBA) and most
of the correlators (DiFX, JIVE, MarkIV) need such files to control
correlation. Other CONTROL options imply that other format
files are written in addition to the VEX file. Valid option are
VLBA for VLBA control files,
VEX for stations that don't need any other formats,
VLA for VLA observe files (soon to be retired),
NONE for no control file - the default.
A 'V' in the 5th character will cause a VLBA
control file to be produced with only the DAS (Data Aquisition System
-- BBC's, formatter, recorder etc) parameters. It is meant for
cases with a VLBA style VLBI backend, but something else for telescope
control. If the first
4 characters are VLBA, this will be the only file. If they are
something else, both the other type of file and the reduced VLBA file
will be produced. This is the default when CONTROL = VLA.
- Gives the type of Data Acquisition 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, RDBE, RDBE2, DBBC, MKIV, VLBA4, MKIII, S2, K4, K5, VERA, VSOP, LBA and NONE (the default). Note that
for Mark II scheduling (now 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. The RDBE and DBBC are digital
systems containing FPGA chips that can support multiple personalities.
Those personalities are specified in the setup file since they can
change between schedules, or even scans. The personalities are
specified with DBE setup file parameter.
The RDBE2 option is the same as the RDBE except that
the presence of 2 RDBE units is assumed allowing twice as many
channels with the DDC personality. To use 2 RDBEs with one MARK5C
unit required the use of the VDIF format which is not yet available
for the PFB personality. Also the PFB personality puts out a fixed
2 Gbps which is twice the capacity of the current MARK5C recorders.
- Gives the version of the DBBC.
Currently supported versions are:
- ASTRO is the default DBBCVER. It has 4
IFs, with the following fixed patching: ifa=bbc01 to
bbc04; ifb=bbc05 to bbc08; ifc=bbc09 to bbc12;
ifd=bbc13 to bbc16.
- GEO has 2 IFs with the following fixed patching:
ifa=bbc01 to bbc08; ifb=bbc09 to bbc16.
- HYBRID has 3 IFs with the following fixed
patching: ifa=bbc01 to bbc04; ifb=bbc05 to bbc08;
ifc=bbc09 to bbc16.
- Gives the type of tape recorder(s) present
Valid options are: VLBA, MKIV, VLBA4, MKIII,
S2, K4, K5, VERA, VSOP, MARK5A,
MARK5B, MARK5C, 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.
- Tells SCHED how many BBC's or VC's are at the
- 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. Note that, even with Mark5A disks, this
may need to be set to 2 to allow 512 Mbps recording, which requires
two heads or two drives to give 64 tracks. NDRIVES 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.
- 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.
- 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, MARK5B, LBADR
and NONE (the default).
- 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.
- Up to 200 azimuths at which horizon elevations
are given in 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 details and performance:
- 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).
- 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.
- The axis offset in meters. Not used by SCHED.
Can be put in the locations catalog.
- 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.
- 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.
- The slew rate for the first axis in degrees
per minute for all mount types.
- The slew rate for the second axis in degrees
- The acceleration for the first axis in degrees
per second squared for all mount types. If one value is given, it is
assumed to apply to both acceleration and deceleration. If two
values are given, the first is for acceleration and the second for
deceleration (although for the calculations, they are interchangeable).
- The acceleration for the second axis in degrees
per second squared. If one value is given, it is
assumed to apply to both acceleration and deceleration.
Scan timing information:
- 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.
- 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.
- Lets SCHED know when the station measures
system temperatures. Arguments are text of 4 characters. The viable
options so far are ``gap'' and ``cont'' that inidicate the system temperature
measurements, or at least cal measurements, are done in the gap between
scans or continuously during observing. The VLBA uses an 80Hz cal switch
and measures cal-on and cal-off powers from which, using a known cal
temperature, the system temperature can be derived. Typical field system
controlled stations fire the cal once at the start of a scan and measure
the on and off power. SCHED will warn if there is inadequate time to
do this if TSCAL=GAP, but not when TSCAL=CONT. This facility is still
not fully installed as of Nov. 5, 2008.
- 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.
- This is a time to be added to the slew
calculation to allow for the set-and-remember power level adjustments
that happen on the VLBA (RDBE) or VLA the first time a particular
setup is seen. Like MINSETUP, the time can overlap with slews
so functionally, this parameter acts exactly like MINSETUP but
only for the first scan with a particular setup. The VLBA needs 15
seconds. The VLA needs 60 seconds. As of Nov. 2012, the VLA actually
needs this every time there is a slight frequency change (like new
Doppler shift), but we will try to get that changed to be only for
more major changes. Note that, if the first scan with a setup is
non-recording, non-pointing, and non-phasing, the scan itself will be
accepted as the level setting (DUMMY on the VLA) scan. This allows
for explicity insertion of DUMMY scans.
Below is a sample entry from the RDBE based version of the standard
station catalog. The full catalog a can be examined
version that uses MARK5A at the VLBA and
for the RDBE
STATION=VLBA_MK STCODE=Mk CONTROL=VLBA
DBNAME = MK-VLBA
MOUNT=ALTAZ AX1LIM=-90,450 AX2LIM=2.25,90 AX1RATE=86.8 AX2RATE=28.3
TSETTLE=6 TLEVSET=5 MINSETUP=5 DAR=RDBE NBBC=16
DISK=MARK5C MEDIADEF=DISK TSCAL=CONT
! 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,
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
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