[daip] FRING

[William Junor]

Another issue:

   I'm working on some VLBA 3mm datasets and, as you'd imagine, this
analysis is messy and difficult (low SNR, no phase cals, tropospheric
weather impacts, etc.).  However, I'm becoming increasing frustrated
with FRING --- or, more correctly, the documentation for FRING.

   For example, what exactly is going on with SOLINT, SOLMIN and SOLSUB? 
I understand that I can create solutions for partially overlapping
SOLINTs, but are these recovered solutions somehow averaged over

   SOLMIN * (SOLINT/SOLMIN)  ?

Is this some attempt to implement some of the approaches in Rogers,
Doeleman & Moran (1995)?

   It's really not clear from the documentation (EXPLAIN FRING or from the
version of the Cookbook that I'm using (which is 31DEC06)).  I guess I
could open up the code and take a look but perhaps it's just worth
asking the question here to start.

   I'd say that this is symptomatic of several problems that I've had with
the most recent analyses that I've done in AIPS.  (Other examples: I
tried to use the data simulation programs ---- DTSIM and friends ---
but this was an exercise in frustration.  Or UVFLG using the text file
input.)  Yes, the programs do often work as advertised --- often after
a lot of trial-and-error --- but it's not clear how to steer them or
what the motivations for program enhancements are sometimes. 
Sometimes, the examples given in the EXPLAIN files are so trivial that
they don't really help with the more messy approaches for which we need
the enhancements --- e.g. UVFLG text input.  And, sometimes, the
explanations are so confused that I'm not sure what's supposed to
happen. (Example: UVFLG EXPLAIN text makes me think that the
alternative text input method only allows a limited sub-set of flagging
operations. Can this be true?)

   My guess would be that the AIPS support is so thin now that there's not
enough capacity in the system to support the crafting of better
documentation.  However, such an approach will have some impact on our
ability to analyze and publish the results of VLBA observations. 
(Which, of course, has a larger impact i.e. the Senior Review.)

   As you'd imagine, I'm sympathetic to the plight of the DAIP, having
been there myself a while ago.  But if a relatively well-informed user
like me is frustrated with the documentation, then what does this say
about the overall state of the project?

   Perhaps an answer to the larger philosophical questions are beyond us
but can I have some enlightenment on FRING, please?


                                       Bill


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