Next: Navigation Post-Observation Products
Previous: Ground Tracking Station (GTS) Products

• VLBI Tapes
• GRT Log File
• GRT Calibration Data
• GRT Clock Offset Data
• GRT Gain Curves
• GRT Status

VLBI Tapes

• GRT to Correlators

What: The VLBI data will be recorded on VLBI tapes of the type appropriate for the scheduled correlator for a given support session.

How: Tape labelling and shipping schemes are available by e-mail from vlbatape@nrao.edu for VLBA tapes and are given in "S2 SVHS Tape Handling Overview for RadioAstron" for S2 tapes. Shipping addresses for correlators are given in Mission Element Points-of-Contact.

When: These tapes must arrive at the designated correlator within 2 weeks of the observation.

Where: Tape shipments should be logged with the tape tacking software of the appropriate correlator as described in VLBI Tape Management.

back to top

GRT Log File

• GRT to Regional Servers

What: Co-observing GRTs will each generate a log file identical to those for ground-based VLBI experiments.

How: Log formats vary between recording formats. Log file names will include the observation code and the 2-letter station code. The VLBA generates one single TSM file containing the information for all participating GRTs within the VLBA and the VLA: the MkIII sections of this file will constitute the log files for correlators other than that at Socorro.

When: File will be made available within a week of the observation.

Where: Each GRT will place the log file on its designated regional server (Regional Servers for GRT logs etc), in the sub-directory named MMMYY for the month and year in which the observation began (in UTC), e.g. may97. For DSN telescopes the files will be placed on the DSN FTP site (see Mission Element FTP sites) in directory /pub/vlbiscpr.

back to top

GRT Calibration Data

• GRTs to Regional Servers

What: GRTs will make available data required for amplitude calibration of their data. Ideally, phase calibration data and a flag table will also be made available, although this is unlikely to be the case for all GRTs initially.

How: The data should be made available in a format which can be read by AIPS: i.e. ANCAL or ANTAB for amplitude calibration data, PCLOD for phase calibration data, and UVFLG for flagged data. The VLBA generates a single TSM file which contains this information for all participating GRTs within the VLBA and the VLA. The bare minimum will be an amplitude calibration data file. These are typically named OBScal.XX, where OBS is the observation code, and XX is the GRT '2-letter code' (which is 'VLBA' for the VLBA and 'Y' for the VLA).

When: File(s) will be placed on the regional server within a week of the observation.

Where: Each GRT will place the file(s) on its designated regional server (Regional Servers for GRT logs etc) in the sub-directory named for the month and year in which the observation began (in UTC). For DSN telescopes the files will be placed on the DSN FTP site (see Mission Element FTP sites) in directory /pub/vlbiscpr.

back to top

GRT Clock Offset Data

• GRTs to Regional Servers

What: GRTs should monitor the offset between their station clock and a time standard (ideally GPS). This monitoring should be undertaken both during and between RadioAstron observations - at least weekly - to allow the station clock drift to be accurately modelled.

How: The format for these files is given in
http://www.nfra.nl/reduce/describe/vlbi/GPS_prog_jdr.html.
The preferred file naming convention is GPS.xx, where xx is the 2-letter code for the GRT.

When: Files will be updated at least weekly.

Where: Files are placed by GRTs on their regional server (Regional Servers for GRT logs etc) in the sub-directory named for the month and year (e.g. may97) below the sub-directory named gps. For DSN telescopes the files will be placed on the DSN FTP site (see Mission Element FTP sites) in directory /pub/vlbiscpr.

back to top

GRT Gain Curves

• GRTs to Regional Servers

What: Gain as a function of elevation, ideally parametrized as a polynomial.

How: See the files below as examples.

When: Files will be regularly updated.

Where: Files are placed by GRTs on their regional server (Regional Servers for GRT logs etc).
For the EVN these are in the evngains files in the cal sub-directory of the EVN FTP site.
For the VLBA these are available by anonymous FTP from ftp.aoc.nrao.edu (146.88.1.103) in the file pub/vlba_gains.key.
For Japanese GRTs these will be available from the Mitaka FTP site (see Mission Element FTP sites).
For Australian GRTs these will be available from the ATNF WWW site.

back to top

GRT Status

• GRTs to RSOG

What: GRTs will not provide regular status reports, but will operate assuming 'no known problems' and will provide reports at any change of status. Any known problems with a GRT should be communicated (by the GRT itself, by correlators, or by PIs) to the RSOG as soon as possible. The RSOG will communicate this information to all other elements that may be affected. Serious problems will result in that GRT being withdrawn from scheduling until the problem is fixed.

How: Email to RSOG@asc.rssi.ru . Suggested format as given in GTS Status Reports.

When: As soon as possible after the problem is discovered, and again as soon as the problem is fixed.