[evlatests] Continued degradation of C-band sensitivity

[Rick Perley]

    Sensitivities of the EVLA antennas at C-band are continuing to 
degrade.  I've analyzed data taken last Friday, and compared these to 
results obtained this morning. 

    For RCP at 4835 MHz, the Friday and Monday effective Tsys values (in 
Jy) are listed below:

    Antenna     18 July         22July
-------------------------------------------
            1             53               51
            2             59               55
            4             58               74
            5             58               74
           11            54               79
           13            47               46
           14            50               52
           16            51               51
           17            73               94
           18            47               46
           19           210            645
           21            53               60
           23            56               70
           24            90              100
           25            54                80
           26            73                84
------------------------------------------------

    Note that:

    1) Antennas 1, 2, 13, 14, 16, 18 have not worsened.
    2) Antennas 4, 5, 11, 17, 21, 23, 25, and 26 have all degraded 
significantly
    3) Antenna 19 is truly bad. 

    As a reminder:  Teff = 45 is the project goal. 

    I also reviewed the Teff data taken since June.  The degradation in 
sensitivity began on July 10 -- exactly coincident with the onset of 
heavy rains at the VLA site.