[daip] PCAL using PMODEL or SU table model fails for simple VLA data set
Michael Rupen
mrupen at aoc.nrao.edu
Wed Aug 23 15:04:48 EDT 2000
Greetings O D-Aip,
pursuant to Chris' suggestion, I happily went off to run PCAL on my
snapshot VLA continuum data set, using 1331+305 (3C286) as the sole pol'n
calibrator. The problem then was to insert the model for the source
polarization. So far as I can tell there are two methods, neither of which
appear to work.
(1) PMODEL
Non-zero PMODEL purports to be used instead of a CC model. So, I set
PMODEL= I, Q, U, 0, 0, 0, with
I= 7.4617 (from SETJY)
Q= I * 0.11 * cos(66) (from cal. manual)
U= I * 0.11 * sin(66) (from cal. manual)
which means pmodel= 7.4617, 0.3338, 0.7498, 0
(note that this is strictly correct only for the 1st IF -- Chris F.
tells me he's not sure whether multiple runs of PCAL, with different
BIF/EIF settings, can work or not; he suspects that only the results
of the last run may be saved)
There are two BPARMs which may or may not be relevant.
BPARM(3)=1 solves for the R-L phase difference, which seemed like a
Good Thing (& was recommended by Chris F.)
BPARM(10)=1 "fixes the source pol'n params to the values given in the
SU table", which seemed like a Bad Thing here.
So, I first tried PCAL with PMODEL as above, BPARM(3)=1, BPARM(10)=0:
AIPS 1: PCAL Task to compute polarization corrections
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: INNAME '20000803 ' Input UV file name (name)
AIPS 1: INCLASS 'C BAND' 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: Data selection (multisource):
AIPS 1: CALSOUR '1331+305 ' Sources to calibrate with
AIPS 1: *rest ' '
AIPS 1: TIMERANG *all 0 Time range to use.
AIPS 1: SELBAND -1 Bandwidth to select (kHz)
AIPS 1: SELFREQ -1 Frequency to select (MHz)
AIPS 1: FREQID 1 Freq. ID to select.
AIPS 1: BIF 1 Lowest IF number 0=>all
AIPS 1: EIF 1 Highest IF number 0=>all
AIPS 1: ANTENNAS *all 0 Antennas to solve for.
AIPS 1: UVRANGE 0 0 UV range in kilolamdba
AIPS 1: SUBARRAY 0 Subarray, 0=>all
AIPS 1: Cal. info for input:
AIPS 1: FLAGVER 1 Flag table version
AIPS 1: DOCALIB 2 If >0 calibrate data
AIPS 1: = 2 calibrate weights
AIPS 1: GAINUSE 2 CAL table to apply.
AIPS 1: CLEAN map (optional)
AIPS 1: IN2NAME ' ' Cleaned map name (name)
AIPS 1: IN2CLASS ' ' Cleaned map name (class)
AIPS 1: IN2SEQ 0 Cleaned map name (seq. #)
AIPS 1: IN2DISK 0 Cleaned map disk unit #
AIPS 1: INVERS 0 CC file version #.
AIPS 1: NCOMP *all 0 # comps to use for model.
AIPS 1: 1 value per field
AIPS 1: FLUX 0 Lowest CC component used.
AIPS 1: NMAPS 0 No. Clean map files
AIPS 1: PMODEL 7.4617 0.3338 Source poln. model
AIPS 1: 0.7498 *rest 0
AIPS 1: SOLINT 0 Soln. interval (min) 0=>10.
AIPS 1: SOLTYPE 'APPR' Solution type:
AIPS 1: 'ORI-', 'APPR', 'RAPR'
AIPS 1: PRTLEV 1 Print statistics 0=>none
AIPS 1: 1 = some, 2 = lots. Use 1.
AIPS 1: REFANT 15 Reference antenna, 0=none.
AIPS 1: BPARM 0 0 Task enrichment parameters
AIPS 1: 1 *rest 0 for SOLTYPE 'ORI-' only:
AIPS 1: (1) if > 0 use default
AIPS 1: initial feed parameters.
AIPS 1: (3) if > 0 then fit for R-L
AIPS 1: phase difference
AIPS 1: (4) initial R-L phase
AIPS 1: (5) >0 solve for Vpol.
AIPS 1: (6) >0 fix ref. ori. 1
AIPS 1: (7) >0 fix ref. ori. 2
AIPS 1: (8) >0 fix all orientations
AIPS 1: (9) >0 fix all ellipticities
AIPS 1: (10) >0 fix source poln.
AIPS 1: CPARM *all 0 Task enrichment parameters
AIPS 1: (1) > 0 => average in IF
AIPS 1: and find common solution.
AIPS 1: (8) > 0 => max. no. iter
AIPS 1: (9) > 0 => conv. tolerance
AIPS 1: (10) > 0 => conv. tol.
AIPS 1: BADDISK *all 0 Disk no. not to use for
AIPS 1: scratch files.
After copying the AN, SU, and CL tables back over from the TASAV'd tables
(paranoia being another Good Thing), I got the following results:
PCAL 1: Task PCAL (release of 31DEC99) begins
PCAL 1: Processing IF number 1
PCAL 1: VISDFT: Begin DFT component subtraction
PCAL 1: VISDFT: Model components of type Point
PCAL 1: VISDFT: Begin DFT component subtraction
PCAL 1: VISDFT: Begin DFT component subtraction
PCAL 1: VISDFT: Begin DFT component subtraction
PCAL 1: RMS residual = 8.293E-03
PCAL 1: Interferometer Element 1
PCAL 1: R: Amp = 0.08520+/- 0.00003 Phase(deg) = 40.70+/- 0.01
PCAL 1: L: Amp = 1.15786+/- 0.00003 Phase(deg) = -141.60+/- 0.00
PCAL 1: Interferometer Element 2
PCAL 1: R: Amp = 0.06115+/- 0.00003 Phase(deg) = 80.36+/- 0.02
PCAL 1: L: Amp = 1.07556+/- 0.00003 Phase(deg) = -139.18+/- 0.00
PCAL 1: Interferometer Element 3
PCAL 1: R: Amp = 0.07508+/- 0.00003 Phase(deg) = 56.74+/- 0.01
PCAL 1: L: Amp = 1.13659+/- 0.00002 Phase(deg) = -143.83+/- 0.00
PCAL 1: Interferometer Element 4
PCAL 1: R: Amp = 0.07322+/- 0.00003 Phase(deg) = 19.57+/- 0.01
PCAL 1: L: Amp = 1.17792+/- 0.00003 Phase(deg) = -142.61+/- 0.00
PCAL 1: Interferometer Element 5
PCAL 1: R: Amp = 0.09064+/- 0.00003 Phase(deg) = 45.51+/- 0.01
PCAL 1: L: Amp = 1.09924+/- 0.00003 Phase(deg) = -143.20+/- 0.00
PCAL 1: Interferometer Element 6
PCAL 1: R: Amp = 0.07740+/- 0.00003 Phase(deg) = 39.69+/- 0.01
PCAL 1: L: Amp = 1.11505+/- 0.00003 Phase(deg) = -143.97+/- 0.00
PCAL 1: Interferometer Element 7
PCAL 1: R: Amp = 0.07937+/- 0.00003 Phase(deg) = 15.13+/- 0.01
PCAL 1: L: Amp = 1.14188+/- 0.00003 Phase(deg) = -142.60+/- 0.00
PCAL 1: Interferometer Element 8
PCAL 1: R: Amp = 0.04066+/- 0.00003 Phase(deg) = 37.24+/- 0.03
PCAL 1: L: Amp = 1.13115+/- 0.00003 Phase(deg) = -141.63+/- 0.00
PCAL 1: Interferometer Element 9
PCAL 1: R: Amp = 0.16345+/- 0.00003 Phase(deg) = 118.29+/- 0.01
PCAL 1: L: Amp = 1.05211+/- 0.00003 Phase(deg) = -142.59+/- 0.00
PCAL 1: Interferometer Element 10
PCAL 1: R: Amp = 0.09582+/- 0.00003 Phase(deg) = 24.37+/- 0.01
PCAL 1: L: Amp = 1.14376+/- 0.00003 Phase(deg) = -144.46+/- 0.00
PCAL 1: Interferometer Element 11
PCAL 1: R: Amp = 0.11725+/- 0.00003 Phase(deg) = 67.45+/- 0.01
PCAL 1: L: Amp = 1.07387+/- 0.00003 Phase(deg) = -140.81+/- 0.00
PCAL 1: Interferometer Element 12
PCAL 1: R: Amp = 0.04270+/- 0.00003 Phase(deg) = 82.81+/- 0.02
PCAL 1: L: Amp = 1.09994+/- 0.00003 Phase(deg) = -140.54+/- 0.00
PCAL 1: Interferometer Element 13
PCAL 1: R: Amp = 0.07410+/- 0.00003 Phase(deg) = 23.82+/- 0.01
PCAL 1: L: Amp = 1.15122+/- 0.00003 Phase(deg) = -143.57+/- 0.00
PCAL 1: Interferometer Element 14
PCAL 1: R: Amp = 0.11532+/- 0.00003 Phase(deg) = 48.03+/- 0.01
PCAL 1: L: Amp = 1.09348+/- 0.00003 Phase(deg) = -141.80+/- 0.00
PCAL 1: Interferometer Element 15
PCAL 1: R: Amp = 0.00000+/- 0.00000 Phase(deg) = 6.30+/- 0.00
PCAL 1: L: Amp = 1.07367+/- 0.00003 Phase(deg) = -139.87+/- 0.00
PCAL 1: Interferometer Element 16
PCAL 1: R: Amp = 0.12832+/- 0.00003 Phase(deg) = 0.80+/- 0.01
PCAL 1: L: Amp = 1.18407+/- 0.00002 Phase(deg) = -142.25+/- 0.00
PCAL 1: Interferometer Element 17
PCAL 1: R: Amp = 0.08724+/- 0.00003 Phase(deg) = 65.77+/- 0.01
PCAL 1: L: Amp = 1.06427+/- 0.00003 Phase(deg) = -141.73+/- 0.00
PCAL 1: Interferometer Element 18
PCAL 1: R: Amp = 0.06012+/- 0.00002 Phase(deg) = 75.80+/- 0.02
PCAL 1: L: Amp = 1.06694+/- 0.00002 Phase(deg) = -142.22+/- 0.00
PCAL 1: Interferometer Element 19
PCAL 1: R: Amp = 0.06735+/- 0.00003 Phase(deg) = 87.97+/- 0.02
PCAL 1: L: Amp = 1.04559+/- 0.00003 Phase(deg) = -141.10+/- 0.00
PCAL 1: Interferometer Element 20
PCAL 1: R: Amp = 0.08734+/- 0.00003 Phase(deg) = 143.61+/- 0.01
PCAL 1: L: Amp = 1.06166+/- 0.00003 Phase(deg) = -140.42+/- 0.00
PCAL 1: Interferometer Element 21
PCAL 1: R: Amp = 0.05853+/- 0.00003 Phase(deg) = 40.99+/- 0.02
PCAL 1: L: Amp = 1.10835+/- 0.00003 Phase(deg) = -143.26+/- 0.00
PCAL 1: Interferometer Element 22
PCAL 1: R: Amp = 0.17620+/- 0.00002 Phase(deg) = 65.74+/- 0.01
PCAL 1: L: Amp = 1.08146+/- 0.00002 Phase(deg) = -149.05+/- 0.00
PCAL 1: Interferometer Element 23
PCAL 1: R: Amp = 0.07035+/- 0.00003 Phase(deg) = -16.22+/- 0.01
PCAL 1: L: Amp = 1.16213+/- 0.00002 Phase(deg) = -140.39+/- 0.00
PCAL 1: Interferometer Element 24
PCAL 1: R: Amp = 0.03587+/- 0.00002 Phase(deg) = 34.63+/- 0.03
PCAL 1: L: Amp = 1.07429+/- 0.00002 Phase(deg) = -139.93+/- 0.00
PCAL 1: Interferometer Element 25
PCAL 1: R: Amp = 0.00000+/- 0.00002 Phase(deg) = 0.00+/- 0.00
PCAL 1: L: Amp = 0.00000+/- 0.00002 Phase(deg) = 0.00+/- 0.00
PCAL 1: Interferometer Element 26
PCAL 1: R: Amp = 0.04200+/- 0.00003 Phase(deg) = 49.13+/- 0.02
PCAL 1: L: Amp = 1.09242+/- 0.00003 Phase(deg) = -142.00+/- 0.00
PCAL 1: Interferometer Element 27
PCAL 1: R: Amp = 0.07005+/- 0.00002 Phase(deg) = 67.26+/- 0.01
PCAL 1: L: Amp = 1.09502+/- 0.00002 Phase(deg) = -142.08+/- 0.00
PCAL 1: Interferometer Element 28
PCAL 1: R: Amp = 0.08165+/- 0.00003 Phase(deg) = 96.44+/- 0.01
PCAL 1: L: Amp = 1.08130+/- 0.00003 Phase(deg) = -141.97+/- 0.00
PCAL 1: Interferometer Element 29
PCAL 1: R: Amp = 0.00000+/- 0.00002 Phase(deg) = 0.00+/- 0.00
PCAL 1: L: Amp = 0.00000+/- 0.00002 Phase(deg) = 0.00+/- 0.00
PCAL 1: Calibration source 1
PCAL 1: Q+iU=( 0.00000, 0.00000) +/- ( 0.000013, 0.000013) Jy
PCAL 1: Pol. inten. = 0.00000 +/- 0.000018 Jy, angle = 0.00 +/-
0.000 deg
PCAL 1: 1331+305 I = 7.4617 Q = 0.0000 U = 0.0000 V = 0.0000
Jy
PCAL 1: Appears to have ended successfully
PCAL 1: mithril 31DEC99 TST: Cpu= 0.6 Real= 2
*** NOTE that Q=U=V=0 for the calibrator!!! ***
These values have also been entered into the SU table. Of course,
this might simply be a "printing" error, but the sol'ns look kinda odd --
the LCP amps for all antennas are about 1.1, the RCP amps. all about 0.07.
So, maybe I have to set BPARM(10)=1 to keep Q,U as I set them. So I tried
copying over the tables again, and re-running PCAL with identical inputs but
BPARM(10)=1. The result is absolutely identical, to every sig. figure
of the Amp/Phase results (checked with diff).
Btw, LISTR/MATX says Q=0.972, U=7.548 -- so the frac. pol'n is 102% :}
vs. original (pre-PCAL, or DOPOL=-1) Q= 0.84, U=0.13, 11% pol'n.
(2) SU table
Well, maybe this is all because I'm trying to use PMODEL. BPARM(10)=1
purports to take the source pol'n model from the SU table -- let's try
that! [This has the further advantage -- if it works -- that it might
allow one to solve for both IFs at once, using the correct flux density
for the two IFs. Avoid that until getting one IF to work though...]
* TACOP the tables again
* SETJY to set pol'n params:
sour '1331+305',''
bif 1 ; eif 1 ; zerosp 7.4617,7.4617*0.11*cos(66),7.4617*0.11*sin(66),0
opty ''
--> LISTR/SCAN shows the SU table as desired
* tget pcal ; bparm(10) 1 ; bparm(3) 1 ; pmodel 0
This gives
PCAL 1: Task PCAL (release of 31DEC99) begins
PCAL 1: Processing IF number 1
PCAL 1: Solution is indeterminate.
PCAL 1: Purports to die of UNNATURAL causes
PCAL 1: mithril 31DEC99 TST: Cpu= 0.3 Real= 0
AARGH!!!!!
I admit that one could also try creating a CLEAN model with pol'n components
& try using that; it's hard to believe that would work, and harder to
believe I would manage to get the model into the correct format :}
One other small nit, I still think it would be nice to be able to run
CLCOR without doing PCAL first (though I admit this would not be a big deal,
if PCAL were working) -- the dominant error for the VLA at least is simply a
rotation of the pol'n angle, and it would be nice simply to be able to
insert that. I can imagine though that handling both this & the standard
(post-PCAL) case would make for yucky coding.
Cheers, and thanks for looking into this,
Michael
p.s. As before, the test data if desired are available on mithril, user
number 11. The TASAV data set is 20000803.CTASAV.1
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