[daip] APCAL not working properly.
Amy Mioduszewski
amiodusz at nrao.edu
Mon Mar 23 13:06:58 EDT 2015
Eric,
Talked to Craig by phone. This is the same as a Bietenolz problem that he sent
to VLBA helpdesk, i.e., GC entries for IFs 1 and 6 only. I thought it was
Beitenholz's weird data (he had a difficult correlation that used a non-standard
version of DiFX), so I thought that was the problem. Craig tried FITLD in 'NEW'
and the GC table appears OK, so it looks like it is FITLD. I will see if I can
reproduce on data of my own.
Amy
On 03/22/2015 10:18 PM, R. Craig Walker wrote:
> With this message, I will describe my problem. If further debugging is
> needed, I'll try to reproduce it at the AOC (I'm working on a Mac at home
> using a recently upgraded 31DEC15 AIPS).
>
> I am calibrating 20cm VLBA data taken with the PFB (8 dual pol channels)
> in February 2015 and correlated last week.
>
> The GC table appears to be fine. There are reasonable K/Jy values for all
> IFs. The gain curve has 1.0 for the first element, INDE for the rest.
> X_val and Y_val are INDE (I'm not sure what they are).
>
> The original TY table seems structured ok, but had a moderate number of
> spurious values and quite a bit of noise. I ran TYSMO twice, first to
> clip with long windows, then to smooth with a shorter window. The
> resulting TY table 3 looks good in all channels.
>
> I then run APCAL (inputs below). The resulting gains are in the range of
> 15-20 for IFs 1 and 6 (both polarizations) and around 0.3 for IFs
> 2,3,4,5,7,8. Not good! I ran APCAL without opacity corrections as you
> can see in the inputs.
>
> Any idea why two IF channels seem to get proper calibration while the rest
> get something way too small?
>
> A secondary issue, what I really want is to specify TAO0 and have it use
> that for the opacity without trying to compare Tsys with physical
> temperatures. This is because I think the Tsys variations are due to RFI
> (L band) rather than the troposphere. It is not clear from the
> HELP/EXPLAIN file that this is possible (or at least I'm not seeing it).
> A quick look in the code was also not illuminating. Is what I want to do
> possible? If not, can it be made so?
>
> Now the APCAL inputs:
>
>> inp
> AIPS 1: APCAL Task to generate an amplitude calibration SN table
> AIPS 1: Adverbs Values Comments
> AIPS 1: ----------------------------------------------------------------
> AIPS 1: INNAME 'MAIN_49A8' Input UV file name (name)
> AIPS 1: INCLASS 'MULTI' Input UV file name (class)
> AIPS 1: INSEQ 1 Input UV file name (seq. #)
> AIPS 1: INDISK 5 Input UV file disk unit #
> AIPS 1:
> AIPS 1: ANTENNAS *all 0 Antennas to calibrate
> AIPS 1: SUBARRAY 0 Subarray 0 -> all
> AIPS 1: STOKES ' ' Stokes type ('R','L',' ')
> AIPS 1: BIF 0 Start IF number
> AIPS 1: EIF 0 End IF number
> AIPS 1: FREQID -1 Freq. ID to calibrate
> AIPS 1: SOURCES *all ' ' Sources to calibrate
> AIPS 1: TIMERANG *all 0 Time range to calibrate
> AIPS 1:
> AIPS 1: TYVER 3 TY table version number.
> AIPS 1: GCVER 1 GC table version number.
> AIPS 1: SNVER 0 Output SN table version.
> AIPS 1: 0 -> highest unique
> AIPS 1: OPCODE ' ' Opacity correction opcode:
> AIPS 1: ' ' -> no opacity corr.
> AIPS 1: 'GRID','GRDR','OPAC','OPCR',
> AIPS 1: 'LESQ' -> fit for opacity
> AIPS 1: APARM *all 0 Calibration parameters:
> AIPS 1: (1) -> B factor (def. 1.0)
> AIPS 1: Opacity parameters:
> AIPS 1: (2) -> ZA limit (deg)
> AIPS 1: (3) >=0 use spillover
> AIPS 1: correction
> AIPS 1: (4) > 0 use all FQ in
> AIPS 1: opac. soln.
> AIPS 1: (5) Limit to sec(z) plotted
> AIPS 1: (6) > 0 => normalize Tsys
> AIPS 1: by average Tsys
> AIPS 1: (7) Use IF AP(7) for
> AIPS 1: normalization instead
> AIPS 1: SOLINT 0 Solution interval (min)
> AIPS 1: 0 -> use all data
> AIPS 1: INVERS 1 WX table version number.
> AIPS 1: 0 -> use text file
> AIPS 1: CALIN *all ' ' Text file with weather info.
> AIPS 1: Must be ' ' if using WX
> AIPS 1: table (INVERS).
> AIPS 1: TRECVR *all 0 Receiver temperatures (K);
> AIPS 1: in (R,L) pairs.
> AIPS 1: TAU0 *all 0 Zenith opacities (per ant.)
> AIPS 1: DOFIT -1 -1 Fit type (per ant.)
> AIPS 1: -1 -1 -1 -> no opacity correction
> AIPS 1: -1 -1 0 -> apply TRECVR only
> AIPS 1: -1 -1 1 -> solve for Trec using
> AIPS 1: -1 -1 fitting method spec.
> AIPS 1: -1 -1 in OPCODE; then apply
> AIPS 1: -1 -1 -1 -1
> AIPS 1: -1 -1 -1 -1
> AIPS 1: -1 -1 -1 -1
> AIPS 1: -1 -1 -1 -1
> AIPS 1: -1 -1
> AIPS 1: PRTLEV 0 Print level
> AIPS 1: DOTV -1 TV selection (<0 -> PL file)
> AIPS 1: LTYPE 3 Plot labeling
> AIPS 1: GRCHAN 0 TV Graphics channel to use
>
> Cheers,
>
> Craig
>
>
> ---------------------------------------------------------------------
> R. Craig Walker Array Operations Center
> cwalker at nrao.edu National Radio Astronomy Observatory
> Phone 575 835 7247 P. O. Box O
> Fax 575 835 7027 Socorro NM 87801 USA
> --------------------------------------------------------------web
>
>
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