gtac1 PC has DAT72 drive, astro6 and proj3 have DDS3 drive. On a DAT72 tape about 30GB GMRT data and on a DDS3 tape 10 to 11 GB of GMRT data (GMRT raw data and/or FITS) can be written by tar command or through
aips. Default data area where the GMRT raw data is recorded is
/rawdata for USB data
and /rawdata1 for LSB data. In this area data will be present in the
subdirectory called by day and month e.g. /rawdata/17may;
During the Observations..
Some offline analysis software are available to look at the data.
For any path confusion, source /etc/bashrc for
bash and /etc/csh.cshrc or /etc/cshrc for csh. Source /astro/RC for
bash shell or source '/astro/RC.csh' for
shell. Run the software and say explain. This will give help for the
The following programmes will be useful for any GTAC user.
1. ltahdr : Gives info about the GMRT raw data, which is in 'lta'
format. The rawdata for USB comes with an extension .lta and
LSB with .ltb. Usage: ltahdr -i . Check
'ltahdr --help' for details.
2. tax: Graphical interface to plot the data. Using this programme, one
can monitor the phase and amplitude stability of the data while the
observation is in progress. Type 'tax' and then type 'explain' for more
Converting GMRT raw data to
The GMRT data can be converted into FITS file using two programmes,
listcan and gvfits.
1. listscan : List the scan in the ltafile for converting to FITS
format. Go to /DATA/; make sure there is enough
space. Run listscan (eg: listscan ).
This will create a file with .log extension. Open this file with your
favorite editor. The parameters you might need to change are the
output FITS file name, CLASSIC_NORM (normalisation by self), removing
unwanted antennas or scans, giving path to the FLAG file etc.
1. gvfits : Convert GMRT (lta) data to FITS format. Run gvfits on the
above log file (eg: gvfits test.log). This will take some time
depending on the size of the input file.
Miscellaneous offline programmes:
The following programmes might not come in use for GTAC users
if there are no problems in the observations.
1. xtract: Extract data from lta file in various formats.
2. ltacomb: combines lta files.
3. ltaclean: cleans up ltafiles with gliches in it. First one or two
records can also be removed using this programme (similar to 'QUACK' in AIPS).
4. ltasel: allows data averaging selection.
5. relta: allows averaging in time.
6. offstop: Stop fringe offline by providing suitable tables antenna
coordinates and fixed delays.
7. tcalibbp : Program for bandpass calibration.
How to get into AIPS:
To use aips on these machines, after login do following:
gtac1% newgrp aips
/usr/aips/LOGIN.CSH (for csh) or source
/usr/aips/LOGIN.SH (for bash)
Prefer to use aips id 1010, 1020, 1030, 1040 and 1050 for
visitor1, visitor2, visitor3, visitor4 and visitor5 accounts
respectively. There is /DATA partition kept for aips data purpose.
Make required number of sub directories here and edit .dadevs
Backup of the
It is the
responsibility of the visitor to take backup of their data. No backup
is taken for the /DATA and /analysis area and user
has to take his own backup before he leaves GMRT site. All the files
from the visitor account will be deleted the day following the day
visitor leaves GMRT.