[daip] solve for a complex band pass

[Z.-Q. Shen]

To whom it may concern,

I am trying to run BPASS on an xc data to solve for a complex band pass.
Somehow, I can not obtain satisfactory results. The amplitude part of the
solution shows quick variation cross the total band of 8 MHz with 256 spectral
channels. The observations were made at 43 GHz with the VLBA. However,
I can obtain amplitude band pass response function using ac data only, which
looks good. Below is part of message from running BPASS using the xc data.
The calibrator I used is NRA0530 and PKS 1921-293. No amplitude calibration
(tsys and gain) was applied. I don't understand some lines like

>BPASS2 11:10:41 Antenna  1  IF  1  corr 2  had      2088 excess closure errors

Does this mean there are errors in the data which will worse the solution?
I have used the Hanning smoothing. Except at the edge channels, the profile
of the amplitude part from the complex BP is very similar to the one from the
ac data (see appended plots). Actually, the variation of the amp vs freq can be
seen from the output of the correlator (xcbandfile.ps). Is this because the
calibrators are still not strong enough in each spectral channel? If so, is 
there
anyway we can try to solve out the phase part of the band pass function?

I would appreciate it very much that you can explain to me in some details.

Happy New Year!

Zhiqiang Shen @ISAS of Japan


>BPASS2 11:10:24 Task BPASS  (release of 31DEC00) begins
>BPASS2 11:10:24 Excess closure errors defined at 10.00 percent and  10.0 
>degrees
>BPASS2 11:10:24 Weights in solution will be channel-dependent
>BPASS2 11:10:24 Array name in AN table is VLBA
>BPASS2 11:10:24 Will assume this is data from the VLBA correlator
>BPASS2 11:10:24 and that it is all fringe-rotated to Earth Centre
>BPASS2 11:10:24 Will remove effects of that fringe-rotation
>BPASS2 11:10:24 to provide consistent bandpass calibration
>BPASS2 11:10:24 If incorrect, abort and change array name keyword
>BPASS2 11:10:29 Selecting, editing and calibrating the data with CL vers   7
>BPASS2 11:10:29 Dividing the spectral data by channel 0
>BPASS2 11:10:40 Determining solutions
>BPASS2 11:10:40 Writing BP table    6
>BPASS2 11:10:41  Time=   0/ 11 58 35 IFs=  1 -   1  Chann=   1 -  256 Polzn=LL
>BPASS2 11:10:41 Antenna  1  IF  1  corr 2  had      2088 excess closure errors
>BPASS2 11:10:41 Antenna  2  IF  1  corr 2  had      1830 excess closure errors
>BPASS2 11:10:41 Antenna  3  IF  1  corr 2  had      2113 excess closure errors
>BPASS2 11:10:41 Antenna  4  IF  1  corr 2  had      1986 excess closure errors
>BPASS2 11:10:41 Antenna  5  IF  1  corr 2  had      1919 excess closure errors
>BPASS2 11:10:41 Antenna  6  IF  1  corr 2  had      1908 excess closure errors
>BPASS2 11:10:41 Antenna  7  IF  1  corr 2  had      2022 excess closure errors
>BPASS2 11:10:41 Antenna  8  IF  1  corr 2  had      1957 excess closure errors
>BPASS2 11:10:41 Antenna  9  IF  1  corr 2  had      1747 excess closure errors
>BPASS2 11:10:41 Antenna 10  IF  1  corr 2  had      2202 excess closure errors
>BPASS2 11:10:41 Adjusting solutions to a common reference antenna
>BPASS2 11:10:41 Appears to have ended successfully
>BPASS2 11:10:41 wwopwwop     31DEC00 TST: Cpu=       8.6  Real=      17
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