I have (yet another!!) calibration recipe question. You may be sick of them just as much as I am! Sorry for the wall of text. If I have been unclear please let me know and I will attempt to rephrase.
The context is much the same as my earlier queries. I have a wide distribution of program sources, each with their own secondary calibrator. As we are observing at 7mm, we are to use Uranus to provide the flux density scale. 1921 was used to provide a bandpass calibration. A H-array was used during the observing, and to cut down on the overheads we observed each program source for a straight 10 minutes with the intention of fitting directly to the visibilities bypassing the imaging process. A consequence of this is that we have sparse uv coverage and using options=qusolve in gpcal will produce a degenerative solution.
As we are using a planet, mfboot is to be used to perform the actual flux scaling correction.
The main question I have. Since we are using some source that isn't 1934 to provide a bandpass calibration solution, mfcal assumes a flat spectrum across the band. In order to construct a more accurate flux calibration scale (as outlined in the ATCA user guide) the suggested approach at the 15mm band (where 1934 can be used as a flux calibrator) is to:
- mfcal vis=1921-293 interval=0.1
gpcal vis=1921-293 interval=0.1 nfbin=2
gpcopy vis=1921-293 out=1934-638
gpcal vis=1934-638 interval=0.1 nfbin=2
gpboot vis=1921-293 cal=1934-638
At this point we can use uvfmeas and plot the two CABB IFs (whatever they may be) and fit a flux model that may be used by mfcal to solve for the bandpass while accounting for the spectral slope of a source.
- uvfmeas vis=1921-293.IF1,1921-293.IF2 order=1 options=log,mfflux
mfcal vis=1921-293 flux=<string_from_uvfmeas> interval=0.1
gpcal vis=1921-293 interval=0.1 nfbin=2
- gpcopy vis=1921-293 out=<phase>
gpcal vis=<phase> interval=0.1 nfbin=xyvary,qusolve
gpboot vis=<phase> cal=1921-293
gpcopy vis=<phase> out=<source>
- gpboot vis=1921-293 cal=1934-638
- mfboot vis=1921-293,uranus select=source(uranus)
- gpboot vis=<phase> cal=1921-293
- mfboot vis=<phase>,1921-293 select=source(1921-293)
If there are any other comments/suggestions please let me know. The only other alternative I could think of was to not split the IFs. Treat the dataset for each source as a single UV file. I was unable to get to far with this as I did some frequency switching throughout the run. Although I uvcat'ed the appropriate 7mm IFs together after atlod/uvsplit, the visibilities were not in time order and gpcal fell over.
As any way where I can plot the model of Uranus used by Miriad?
Thanks!