If you wish to apply measured Tsys corrections, you will need to create an ANTAB
file from the various telescope log files. [link to example]
ANTAB
format, with Tsys measurements in units of Jy. These should be placed in the ATNF FTP area for each experiment after the session. DPFU
in the GAIN
group of the ANTAB
file should then be set to 1.0 for these telescopes.ANTAB
or Tsys, off-source flagging and other log files should be in the ATNF FTP area for the given experiment (linked from the observers wiki page). See the notes on LBA log files.DPFU
, if not provided, should then be set to the nominal DPFU: Tsys(K)/Tsys(Jy) from the table of system parameters.POLY=1
) at all VLBI frequencies. Some other potentially useful gain curves of varying ages are provided in ANTAB format here. Below are two more recent gain curves for Hobart and Ceduna courtesy of S. Ellingsen (2008).
Note these are not in the correct format for ANTAB. They can be converted into a table of values for ANTAB:
Ceduna (at 6.7 GHz, should be OK for 8.4 GHz):
1/[3.8e-5*el^2 - 3.575e-3*el + 0.9165]
Hobart (8.4 GHz):
1/(1.1377-2.5673e-2*el+1.1744e-3*el^2-2.1322e-5*el^3)+1.3452e-7*el^4)
ANTAB
file, be sure to edit the antenna names if required, to ensure that the names match with those in the FITS file/AIPS AN
tenna table (usually this will be the two-letter station code, especially for recently correlated data, but should be checked as other antenna names may be used). Also check that the INDEX
keyword value assigns the columns to the correct IFs/polarizations. CL
table should correspond approximately to the corrections from ACCOR
multiplied by the square root of nominal SEFD for each telescope, assuming telescope performance is as expected. (This is not true for data correlated pre-2010, in which case the data have been scaled by the nominal SEFD, and the gain amplitudes should be not too far from 1 if the telescope performed at its nominal sensitivity).