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problems combining ATCA & GMRT HI data

PostPosted: Tue Nov 29, 2016 1:20 am
by Jota
Hi everyone,

Have you ever tried to combine GMRT data with ATCA data?.
I have seen at miriad documentation to know, how to read VLA data into
miriad, but this error came up while I tried to run invert task.

Reading the visibility data ...
### Warning [invert]: Noise variance cannot be determined for GMRT.miriad
### Warning [invert]: ... variable jyperk is missing or non-positive
### Warning [invert]: ... variable systemp is missing or non-positive
### Warning [invert]: Set the variable(s) using puthd

I have tried to get in AIPS the variable systemp but I can't :S .

Thanks a lot,


Re: problems combining ATCA & GMRT HI data

PostPosted: Wed Jan 11, 2017 9:01 am
by Mark.Wieringa
Hi Juliana,

Sorry for the late reply,

You may have solved this by now - but in case you haven't the quickest solution is probably to do as invert suggested and use the puthd task to enter nominal values for the jyperk and systemp parameters. The first one should only affect the theoretical noise estimate. The second one could also affect the weighting of the data (with options=systemp).
If there is significant change of the system temperature with time and you want to use this to reweight the data, you may need to use the varwt option in fits when loading the data.