[daip] FQTOL

[Tracy Clarke (Foreign National)]

Hi,

I did separate the two sidebands so I have one data set from 614 MHz to 
628 MHz which has 614 MHz in channel 1 and positive channel increment. I 
have a second data set with frequencies of 613 MHz to 599 MHz which I 
modified using puthead to have 599 MHz in channel 19 and a positive 
frequency increment. Imagr checks on both of these show it is seeing the 
correct frequencies. I am getting very odd behaviour from DBCON though. 
When I run it (creating a new file) it is modifying the number of 
visibilities in the first input file! The number changes to be a bit less 
than the sum of the visibilities in the two input images. I really don't 
understand what is happening here. What values should I be using for DOPOS 
and FQTOL to combine these data sets correctly? Might it be better if I 
run BLOAT and UVGLU on them? Thanks for the help, I've very confused by 
what is happening. Cheers,
 							Tracy


On Fri, 26 May 2006, Eric Greisen wrote:

> Tracy Clarke (Foreign National) writes:
>
> > I'm trying to DBCON two GMRT data sets from different sidebands and the
> > frequency difference between them is 1.25 MHz. DBCON is refusing and after
> > looking at the code it looks like it will accept frequency differences up
> > to 1 MHz? I'd prefer to add these in the uv plane rather than image plane,
> > what would be the best thing for me to do in this case? (Other than
> > not use the GMRT ;) ). Thanks,
>
> You do not want to mix data that have different separations between
> the 2 or more IFs.  A MHz at 600 MHz is a big deal.  You can UVCOP the
> IFs to separate them and the DBCON the whole lot.  This will get the
> right uvw's.
>
> Eric Greisen
>

-- 
Dr. Tracy Clarke
Research Astronomer
Naval Research Laboratory, Code 7213
Phone: (202) 404-4297
Fax: (202) 404-8894