[daip] AIPS Query

[Eric Greisen]

dbgob at brandeis.edu writes:
 > Eric,

    Please use daip at nrao.edu for quieries - I do go on vacation
sometimes
 > 
 > I just pulled in some archival data from the NRAO and it was done in  
 > Line Mode. I did a quick perusal of the AIPS manual but have not found  
 > a good walk through on how to work with data with the VLA in this  
 > mode. Do you have any good suggestions? Chapter 8 discusses some of  
 > this as well as 4.7. I have also tried to just run with the normal  
 > calibration laid out in chapter 4 and then pushing to Difmap but run  
 > into some interesting problems. Thoughts?

     There is quite a bit about spectral-line reduction including a
whole appendix.  If these are pseudo-continuum data with multiple
channels only to avoid bandwidth smearing, then life is rather easy.
One still calibrates with CALIB either with a channel-0 data set of
with the average of channels directly specified in CALIB.  A bandpass
cal is a good thing even in this mode.  difmap is easier in some ways
to use but IMAGR offers a great deal more capability.


 > Also, when using task 'uvflg' why am I not allowed to flag data by  
 > using aparm? For example, I will choose a source and then specify  
 > aparm 100 200 0 to say to remove points lower than 100 and higher than  
 > 200. I continually receive:
 > 
 > UVFLG1: Task UVFLG  (release of 31DEC07) begins
 > UVFLG1: NO AMPL. OR WGT. CLIPPING WITH FLAG TABLES
 > UVFLG1: NOTE THAT MULTI-SOURCE FILES MUST USE FLAG TABLES
 > UVFLG1: Purports to die of UNNATURAL causes
 > UVFLG1: galaxy       31DEC07 TST: Cpu=       0.0  Real=       0
 > AIPS 1: Resumes
 > 
 > 
 > Thoughts?

Yes - use the task designed to do this - CLIP is you have the latest
version of AIPS or CLIPM with an older version (including older
31DEC07).

UVFLG is really mostly for single-source files in some of its off-beat
modes.

Eric Greisen