[daip] ACFIT

[Jim Ulvestad]

Hi Colleen,

>From your first message, I expected that you only wanted to use one
IF to determine the gains.  But now this one looks like you want to
determine each IF separately.  So that confuses me a bit.  Do you
have the AIPS Cookbook?  If not, take a look at it on the web.
Pages 9-33 and 9-34 seem to describe the procedure, though not
quite perfectly.  It looks like you use SPLIT to copy off a
file with the self-spectra.  If you want to use only one IF as
an input, you need to set BIF and EIF in SPLIT to get the one
you want.  Then you run ACFIT, with the multi-source data file
as inname, and the single-source data file as in2name.  Here, you 
have to pick which reference antenna you want to use for the
template, and which channels to fit.  This will make an SN table
attached to the original multi-source data set, which you must
then apply using CLCAL (perhaps after running SNSMO first).

Again, let me know if this note plus the Cookbook is enough to
get you there.

jim
Colleen Schwartz wrote:
> 
> Hi,
> 
> I'm trying to use ACFIT to calibrate the amplitudes on a water maser data
> set.  It's W49N, so from what I can figure out, it's strong enough that
> ACFIT is the best way to do the amplitude calibration.  Would it be a good
> idea to separate the IFs and then ACFIT them each separately, then somehow
> merge those two SN tables together into one and copy them back over to the
> original data?
> 
> I was also using KRING to get the rates and delays but it was only giving
> me solutions for 5 of the 11 antennas, which clued me in to the possible
> problem with ACFIT.
> 
> Thanks for replying so quickly - it's hard when I'm the only one here
> using AIPS, I really appreciate your help.
> 
> -Colleen
> 
> > Hi Colleen,
> >
> > No AIPS does not recognize what IF you want.  In fact, KRING and FRING
> > have no capability of picking individual IFs, nor does ACFIT.  What
> > I would recommend doing is using UVCOP or SPLAT to copy the desired
> > IF into a separate file, run KRING or ACFIT  on that file to produce
> > the desired SN table, and copy the SN table back to the original
> > data set using TACOP.
> >
> > I haven't done this myself, so how you apply the SN table will depend
> > on exactly what you're trying to do.  For instance, if you want to use
> > one IF to get the solution, but then apply that to the calibration of
> > all
> > IFs, I'm not sure exactly how to do it, because you presumably need an
> > SN table that covers all the IFs.
> >
> > If you can be a little more specific about exactly what you want to do
> > with the results of ACFIT or KRING, I can probably figure out how to do
> > it.  But I don't want to go down some specific path where I might be
> > wasting my time, without more information.
> >
> > Please let me know if I've given you enough to go on, or if you need
> > me to go further on some specific path.
> >
> > Best,
> > Jim Ulvestad
>