[daip] SPCAL question and problem

Eric Greisen egreisen at nrao.edu
Tue Jun 23 13:39:04 EDT 2009

Hanno Spreeuw wrote:
> Hello,
> I have a question about SPCAL and a small problem. How are the frequency 
> dependent D-terms computed? Are the solutions expressed as coefficients 
> of a polynomial?
> LPCAL seems to export more numbers to the AN table than SPCAL does.
> The problem:
> If I run SPCAL it crashes:
> "castor> SPCAL4: Interferometer Element  13
> castor> SPCAL4:   R: Amp =  0.00403+/- 0.00050 Phase(deg) =  -89.35+/- 
>   4.98
> castor> SPCAL4:   L: Amp =  0.00855+/- 0.00059 Phase(deg) =   95.15+/- 
>   2.82
> castor> SPCAL4: Interferometer Element  14
> castor> SPCAL4:   R: Amp =  0.00004+/- 0.00000 Phase(deg) =  127.40+/- 
>   0.00
> castor> SPCAL4:   L: Amp =  0.00776+/- 0.00059 Phase(deg) =  145.01+/- 
>   3.10
> castor> SPCAL4: True RMS residual =      5.16499338D-01
> castor> SPCAL4: Pre-fit RMS =      9.43064733D-01
> castor> SPCAL4: Purports to die of UNNATURAL causes"
> I "solved" this by adding an extra identical AN table to the dataset. 
> One is deleted, but the remaining one is updated by SPCAL.
> Perhaps this issue has to do with the fact that this is WSRT data.

SPCAL makes a mess of which AN file to do.  It is supposed to take the 
one for SUBARRAY and make a copy to a new temporary file one larger than 
the max, add 2 parameters (ellipticity and orientation) per antenna and 
polarization at BIF only, then delete AN file SUBARRAY, copy max+1 to 
SUBARRAY and then delete the max +1.  Since it did not add the 1 it took 
max for the scratch one, copied SUBARRAY to it etc.  Making a spare one 
as you did "fixes" the bug.  A better fix will arrive with tomorrow's MNJ.

LPCAL does all IFs at once.  SPCAL must be run over and over with you 
looping on IF.

Eric Greisen

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