[daip] New Ticket - [!TSF-216641]: Extra, spurious solution from VLBAMPCL

[Craig Walker]

New Ticket: Extra, spurious solution from VLBAMPCL

I ran VLBAMPCL on a dataset processed on DiFX.  I had specified a one minute time range during a scan of somewhat over 2 minutes.  The time range was inside the scan with at at least several records present both before and after the time range.  The solint specified by the procedure, not a user parameter, appears to have been 10 minutes from the history record.  The resulting SN table has two solutions.  The first is a couple of seconds before the middle of the specified scan range.  The second is almost exactly at the end of the specified time range.  The solutions are sufficiently different that a step is introduced in my data set at the time of the reference scan.  The idea of the "manual pulse cal" that VLBAMPCL does using FRING is that there will be one delay applied to the whole dataset so this step is not good.   POSSM plots of data later than the reference scan indicate that the second solution is not very good.  I'll speculate that it is based on a tiny amount of da!
 ta.

The step also seems to have caused some serious confusion during the scan when I tried to use it to do the cross-hand delays with VLBACPOL.  With my usual reference antenna, the results for one IF were clearly bad.  I suspect that there is some sort of ramp when the interpolation is done by CLCAL.  In fact, such a ramp shows up plotting the CL table with SNPLT.

My guess is that everything went fine for the first solution, but for some reason FRING decided to do a second solution even though there should not have been any data for a second solution.

If you need my data to look at this, we will need to wait until the end of the week.  The data set is at home and I am on travel Tue-Thur.

Cheers,

Craig




Ticket Details
===================
Ticket ID: TSF-216641
Department: AIPS Data Processing
Priority: Default
Status: Open
Link:  https://help.nrao.edu/staff/index.php?_m=tickets&_a=viewticket&ticketid=159