[evlatests] AR637 1jul07: lost 2 of 10 hours

[mrupen at nrao.edu]

AR637:  1jul07 01:36-11:03 IAT  C & X band continuum, 10s averaging
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Evaluation by M. Rupen  2jul07

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SUMMARY
  - overall quite good -- even flags aren't too bad
  - major problems are:
    1- no fringes on x-VLA (EVLA-EVLA seem OK) for first hour
      Unfortunately this includes their only flux and pol'n calibrators!
      (apart from one with no circular pol'n)
    2- Lost last 52 minutes entirely due to D10 problems
      - this is documented in the log
    3- Phase jump at X-band at ~05:00 -- no sign of this in amplitudes or
      at C-band

  Conclusion: have to consult with them on importance of calibration,
    particularly for polarization.  Might be worth scheduling some QUICK
    make-up time to get some data for them on this -- an hour would do it,
    if the system is working.

    Better to load this WITH on-line flags, as those are pretty good.

  General conclusion: should advise current observers NOT to put important
    calibrators at the beginning or at the end of their OBSERVE files --
    the middle is much safer.

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C band
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* no data from ant. 11, as expected
* ant. 19, 21 no fringes
  - correctly flagged
* No fringes on VLA-VLA or EVLA-VLA from beginning through 02:33.
  EVLA-EVLA look OK.
  (includes 1st 3 scans: 1331, 1407, 1613; 1st good data are on 1727)
  - EVLA antennas correctly unflagged
  - VLA antennas should be entirely flagged, but are not
    ...VLA ant. 1 2 3 4 25 are left
    ...also VLA ant. 5 6 7 for 1st scan and ant. 7 for part of 2nd scan
* ant. 13 IF 2L no fringes
  - not flagged
  - IF 2R is weak
* ant. 16 loses fringes for several scans
  - flagged most of the time, probably reasonable
* ant. 13,14 lose fringes (or at least very noisy) for occasional scans
  - some flagged, some not
* ant.  5 is flagged for several scans, although the data look good
* ant. 18 lots of amp. fluctuations
  - flagged for several scans and random times -- should probably be tossed
    entirely
* very little data from 10:11 through the end -- see note in log
  - data aren't flagged, but probably should be

* EVLA antennas come in a record before VLA antennas on many scans, but
  data are hooey

* CALIB results
  - phases look reasonable -- lousy weather for the first couple of hours


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X band
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* no data from ant. 11, as expected
* No VLA-VLA or EVLA-VLA fringes in 1st two scans (1331, 1407)
  EVLA-EVLA look ok
  - VLA ant. 6 7 8 9 10 12 15 22 27 28 should be flagged but aren't
* ant. 13 IF 2L no fringes
  - IF 2R is weak
* ant. 16 loses fringes for several scans
  - mostly flagged until 08:26, but not entirely
* very little data from 10:11 through the end -- see note in log
  - data aren't flagged, but probably should be

* EVLA antennas come in a record before VLA antennas on some scans, but
  data are hooey


* CALIB results
  - Seems to be a phase jump at 05:00 -- 40-90 degrees or so, varies with
    antenna
  - Some odd amp.gains but nothing I'd attribute to the MODCOMPs

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