2023 Session I (c231)

Version from 13:58, 29 May 2024

...

Current version

...

Feedback for PIs - the visibility data in the two FITS-IDI IFs that start at 85308 MHz and the other at 87164 MHz are spectrally incomplete on the baselines to ALMA.

For example, the latter IF covers 87164.0 to 87228.0 MHz, while the standard ALMA setup recorded only up to sky frequency 87210.453125 MHz. Thus the last ~18 MHz of this FITS-IDI IF do not contain proper data from ALMA. Similarly for the IF starting at 85308 MHz. Due to a bug in the DiFX correlator these incomplete visibility records were written out rather than discarded.

In post-processing these two IFs should be flagged on baselines to ALMA.



background/debugging:

All c231d PolConvert.log log files:

# c231d_1151.polconvert-*/PolConvert.log
WARNING! There is no spw that covers all the IF frequencies!
Problematic IFs are:  62,63,64,76,82
 (sometimes 62,63,64,65 or other depending on the scan)

The corresponding DiFX IFs (0-based indices) in c231d_1151:

 fq  61 :     64.000000 MHz USB [4096-ch/32-avg] @ 87164.000000 MHz
 fq  62 :     64.000000 MHz USB [4096-ch/32-avg] @ 87228.000000 MHz
 fq  63 :     64.000000 MHz USB [4096-ch/32-avg] @ 85308.000000 MHz
 fq  75 :     64.000000 MHz LSB [4096-ch/32-avg] @ 85308.000000 MHz
 fq  81 :     64.000000 MHz USB [4096-ch/32-avg] @ 85244.000000 MHz

In the end after Polconversion there remain mixed polarization visibilities,

$ printDiFX.py c231d_1151.difx | grep "AA-"  | grep "\/Y\|\/X"
AA-AA/257/61:87164.0000000U/XX  mjd:60073.00001454 nchan:128 bw:64.0000
AA-AA/257/63:85308.0000000U/XX  mjd:60073.00001454 nchan:128 bw:64.0000
AA-AA/257/61:87164.0000000U/XY  mjd:60073.00001454 nchan:128 bw:64.0000
AA-AA/257/63:85308.0000000U/XY  mjd:60073.00001454 nchan:128 bw:64.0000
AA-AA/257/61:87164.0000000U/YX  mjd:60073.00001454 nchan:128 bw:64.0000
AA-AA/257/63:85308.0000000U/YX  mjd:60073.00001454 nchan:128 bw:64.0000
AA-AA/257/61:87164.0000000U/YY  mjd:60073.00001454 nchan:128 bw:64.0000
AA-AA/257/63:85308.0000000U/YY  mjd:60073.00001454 nchan:128 bw:64.0000
AA-GL/261/61:87164.0000000U/XL  mjd:60073.00001454 nchan:128 bw:64.0000
AA-GL/261/63:85308.0000000U/XL  mjd:60073.00001454 nchan:128 bw:64.0000
AA-GL/261/61:87164.0000000U/XR  mjd:60073.00001454 nchan:128 bw:64.0000
AA-GL/261/63:85308.0000000U/XR  mjd:60073.00001454 nchan:128 bw:64.0000
AA-GL/261/61:87164.0000000U/YL  mjd:60073.00001454 nchan:128 bw:64.0000
AA-GL/261/63:85308.0000000U/YL  mjd:60073.00001454 nchan:128 bw:64.0000
AA-GL/261/61:87164.0000000U/YR  mjd:60073.00001454 nchan:128 bw:64.0000
AA-GL/261/63:85308.0000000U/YR  mjd:60073.00001454 nchan:128 bw:64.0000
AA-OD/266/63:85308.0000000U/XL  mjd:60073.00001454 nchan:128 bw:64.0000
AA-OD/266/61:87164.0000000U/XL  mjd:60073.00001454 nchan:128 bw:64.0000
AA-OD/266/63:85308.0000000U/XR  mjd:60073.00001454 nchan:128 bw:64.0000
AA-OD/266/61:87164.0000000U/XR  mjd:60073.00001454 nchan:128 bw:64.0000
AA-OD/266/63:85308.0000000U/YL  mjd:60073.00001454 nchan:128 bw:64.0000XL
AA-OD/266/61:87164.0000000U/YL  mjd:60073.00001454 nchan:128 bw:64.0000
AA-OD/266/63:85308.0000000U/YR  mjd:60073.00001454 nchan:128 bw:64.0000
AA-OD/266/61:87164.0000000U/YR  mjd:60073.00001454 nchan:128 bw:64.0000
...

VEX file:

ALMA
chan_def = &W : 87210.453125 MHz : L : 62.5 MHz : &CH01 : &BBC07 : &cp;
...
chan_def = &W : 85394.046875 MHz : L : 62.5 MHz : &CH32 : &BBC07 : &cp;

with ch01 covering approx 87147.95 to 87210.45 MHz

hence freq #61 covering 87164.0 to 87228.0

...