General calibration recipe + nfbin questions
Posted: Tue May 19, 2015 2:36 pm
Hi all,
Another few questions. Hopefully they are straight forward and not to silly.
I have data of twenty sources with some 11 phase calibrators, where one of the phase calibrators is 1934. A typical calibration solution I have been using is:
My first question, in the case where 1934 is not only used for bandpass/flux density calibration but also phase, what is the best way to calibrate the data? Is there any need to break the data into two parts - one for the bandpass/flux density where there was 10 minutes of straight time on source, and the second for each of the phase reference scans? Or is it appropriate to simply use step 1 and 2 from above, except with options=xyvary,qusolve in gpcal? Could I make this the 'default' calibration, or would it do something bad to the other 10 secondary phase calibrators? My first thought is that breaking the data into two files would make the most sense, but if gpcal corrects for phase changes through time it wouldn’t matter whether they are broken up or not.
Additionally, I was hoping to get clarification on how nfbin determines the frequency bins when a parameter for it has been supplied. I ask because, as mentioned in the previous thread, I have had to flag the upper end of my 11GHz data. When I supply an nfbin parameter, is it smart enough to compute these bins based on the minimum and maximum frequency of unflagged channels? I would think so simply because gpcal didn’t fall over, but i Would like to be sure. Perhaps including the frequency range of each bin could be included in the output where appropriate as it may be a useful reference?
And finally, I am curious if there are any tasks or ways to inspect the flags file of a uv-file so as to identify the channels which have been flagged - ideally only those which have been flagged for all records? I ask because I plan to divide my data up into multiple sub-bands using the line parameter in invert, and I hope to balance them such that they all have a consistent number of useable channels. Knowing how to do this will definitely help me remain consistent, especially if I try to automated the imaging aspect of the project.
Thanks (again)
Tim
Another few questions. Hopefully they are straight forward and not to silly.
I have data of twenty sources with some 11 phase calibrators, where one of the phase calibrators is 1934. A typical calibration solution I have been using is:
Code: Select all
mfcal vis=1934 refant=3 interval=0.1
gpcal vis=1934 refant=3 interval=0.1 nfbin=4 options=xyvary
gpcopy vis=1934 out=<secondary>
gpcal vis=<secondary> interval=0.1 nfbin=4 options=xyvary,qusolve refant=3
gpboot vis=<secondary> cal=1934
Additionally, I was hoping to get clarification on how nfbin determines the frequency bins when a parameter for it has been supplied. I ask because, as mentioned in the previous thread, I have had to flag the upper end of my 11GHz data. When I supply an nfbin parameter, is it smart enough to compute these bins based on the minimum and maximum frequency of unflagged channels? I would think so simply because gpcal didn’t fall over, but i Would like to be sure. Perhaps including the frequency range of each bin could be included in the output where appropriate as it may be a useful reference?
And finally, I am curious if there are any tasks or ways to inspect the flags file of a uv-file so as to identify the channels which have been flagged - ideally only those which have been flagged for all records? I ask because I plan to divide my data up into multiple sub-bands using the line parameter in invert, and I hope to balance them such that they all have a consistent number of useable channels. Knowing how to do this will definitely help me remain consistent, especially if I try to automated the imaging aspect of the project.
Thanks (again)
Tim