[evlatests] EVLA status as seen by the observer: midnight last night (6-7jul06)

[mrupen at nrao.edu]

AM865  7jul06  05:00-06:00 IAT
------------------------------
M. Rupen  7jul06

Report of data quality (as measured by AIPS weights)

EVLA ant. 13,14,16,18 included

Standard continuum, C X bands
3.3s averaging
elevation 35-45 degrees

OVERVIEW (comparisons are to 3jul06 data):
  6cm:
    ant. 13 remains excellent
    ant. 14 has gotten MUCH worse: no data in IFs AC, very high
      noise in IFs BD
    ant. 16 has also gone waaaay downhill -- much worse noise in all IFs --
      IFs AC are now the worst in the array, while BD went from among the best
      in the array to about the middle of the pack.
      IFs AC show quite unstable amplitudes -- gains vary chaotically,
        by 20%, over an hour
    ant. 18 has no data
  
  4cm:
    ant. 13 has gotten much worse in all IFs (dropped from about average to
      much worse than most VLA antennas)
    ant. 14 is about the same (awful)
    ant. 16 has also gotten much worse -- it's now almost as bad as 14
    ant. 18 remains about the same (poor)
            IFs BD show dropouts (low amp., stable phase) at the same time
              in each IF (but note 3.3s averaging time)

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AIPS weights: median ranking, out of a nominal
  26 antennas
  --> 1 is the best; 26 is the worst <--

          6cm   4cm
  13-A    n.f.   23  **sig.drop from middle
  13-C   ----    24  **sig.drop from middle
  13-B    1      23  **sig.drop from middle
  13-D    2      24  **sig.drop from lower quartile

  14-A   ----    26  
  14-C   ----    23
  14-B   26      26
  14-D   26      26

  16-A   26      25  **sig.drop from lowest quartile
  16-C   26      25  **sig.drop from lowest quartile
  16-B    9      25  **sig.drop from lowest quartile
  16-D   18      25  **even worse than before

  18-A   ----    17  
  18-C   ----    19
  18-B   ----    17
  18-D   ----    20

  ---- ==> no data
  n.f. ==> no fringes (low amp, random phase)

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AIPS weights: median fractional weight
  mean weight is calculated for each record
  fractional weight is the weight for the EVLA antenna,
    divided by that mean
  the median fractional weight is the median value of the
    fractional weights, derived from the distribution across
    all records in which the antenna was present
  --> high is good <---
  --> the average VLA antenna is 1.0 <--
  --> 0.1 is 10 times worse than the average;
     10.0 is 10 times better <--

          6cm   4cm
  13-A    n.f.  0.51
  13-C   ----   0.50
  13-B   1.71   0.56
  13-D   1.39   0.51

  14-A   ----   0.02
  14-C   ----   0.002
  14-B   0.04   0.02 
  14-D   0.03   0.02

  16-A   0.46   0.03
  16-C   0.36   0.03
  16-B   1.11   0.03
  16-D   0.89   0.03

  18-A   ----   0.91
  18-C   ----   0.80
  18-B   ----   0.83
  18-D   ----   0.74

  ---- ==> no data
  n.f. ==> no fringes (low amp, random phase)

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