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Here are John Reynolds' instructions for producing SNAP and procedure
files from ATCA schedules:

1. Prepare AT SCHED schedule, as normal, on LEON.

  • Allow additional setup time at Narrabri for calibration.
  • Add 5 second offset to the reference time to synchronise ATCA source changes correctly.

2. on LEON;

    $ run/nodebug at$run:vsched   (from VLBI account, $ VSCHED will do)\\
    AT schedfile : v100e2\\
    next file [none] :\\
    $ dd v100e2.*.\\

    Directory $2$DKA300:[AT.SCHED]\\

    V100E2.CAT;1                    2/3        8-NOV-1998 11:45:47.45\\
    V100E2.DRG;1                   16/18       8-NOV-1998 11:45:47.26\\
    V100E2.LBA;1                    9/9        8-NOV-1998 11:45:47.37\\
    V100E2.SCH;1                  172/174      8-NOV-1998 00:02:37.14\\
  *  The .DRG file is then used (next step) to make a simple SNAP file. The .LBA file is a skeleton for the LBA correlator.SCH file, while the .CAT file contains the source positions in standard AT format and can be simply copied to elleba::cor$db:*.TAB. (Note: these won't necessarily be the most precise positions for some sources though). The confusing naming conventions (.LBA => .SCH, .CAT => .TAB) are unfortunate legacies, but we're stuck with them short-term).\\

3. Make the SNAP file

        $ skedr\\
         Input DRUDG file :  v088i1.drg\\

         Station code to select [P] :\\

         Experiment name: [v088i1] :\\
          Write ATCA schedule [N] :\\
          Snap file epoch [J2000] :\\
         Station PARKES   : mount type AZEL\\
         Sources read from SKED file:     5\\
         SOURCE: 0823-500 has   1 scans\\
         SOURCE: 1718-649 has   1 scans\\
         SOURCE: J1729-22 has 111 scans\\
         SOURCE: PSR1730  has 104 scans\\
         SOURCE: 1730-130 has   6 scans\\

         Scans by baseline to selected station:\\
         ATCA01   PARKES   MOPRA\\
          223      223      223\\
          Normal Stop\\

4. The above produces a skeleton SNAP file called, in this case, v088i1.snp which may now be hand-edited to add tape control. This is fairly straightfoward, but does require care and checking. See any recent examples of snap files to see how this is done.

5. The companion .prc file is usually cribbed from any recent, similar experiment, modifying the experiment and, and the S2 mode where necessary.


The second schedule is the field system schedule. Again for most LBA
observations this will be provided but for VSOP observations it needs
to be made. In case the field system schedule needs to be made, there
are at least two ways to make it. Firstly, and most simply if the
user is inexperienced with the VLBI scheduling software SCHED (by
Craig Walker, NRAO), the ATCA schedule can be sent to John Reynolds
well before the experiment. From the ATCA schedule the field
system schedules can be made for all the participating telescopes
and delivered to the correct places.

Secondly, if the user is experienced with SCHED, they may wish to
produce all of the schedules themselves. In this case it is suggested
that while preparing the schedule they consult John Reynolds and/or
Tasso Tzioumis, for advice on setup files, S2 configurations etc.
When the keyin format file is prepared and passed through the SCHED
software the output includes two files, <filename>.sum and
<filename>.skd. These are the two files of interest for producing
the field system schedules. To do this, follow these steps:

FTP the <filename>.sum and <filename>.skd files to one of the field system
pc machines (whichever is convenient). At Narrabri this machine is
called v1ca. Login with username oper.

Move the two files to /usr2/sched

Type drudg to run the software that converts the <filename>.skd file
to the field system schedule. Select the station you wish to create
schedules for. Select options 3 (create snap file) and 12 (create
procedure file).

Repeat the above procedure until all the schedules are made for all the

Move the snap file <filename>.snp for each station to the corresponding
field system machine in /usr2/sched and likewise the procedure file
<filename>.prc to /usr2/proc. Alternatively, place all of the
schedules on the VLBI FTP server in Epping and tell all of the relevant
people at each station where they are so that they can be picked up
and placed in the correct areas.

Also, from the <filename>.skd file it is possible to create the CAOBS
schedule for the ATCA and the VLOBS schedule for Mopra. This is done
via a PERL script that can be found in


Run it on the <filename>.skd file by typing

vlba2sched <filename>

and selecting ATCA or Mopra for the schedule output. The output will
be a <filename> file which can be run in the ATCA SCHED
software by going into SCHED and typing @<filename>_

This PERL script is still under development and several things need to
be altered by hand in SCHED. It is worth listing the SCHED output
against the <filename>.sum file to see that the scan times etc all

The SCHED output should be placed in at$sched on LEON for the ATCA or
in at$sched on MOPRA for Mopra, or on the VLBI FTP server in Epping.

lbaops/producingschedules.1142113180.txt.gz · Last modified: 2015/12/18 16:39 (external edit)