[evlatests] Q-band results from tests on June 19, 2006

[Chris Carilli]

I also looked at some Q band data using the EVLA antennas.  It was line 
mode.
As Mark says, 18 and 24 did not work. 

Ants  13 and 14 had same nominal sensitivity as the rest of the VLA.
Ant 16 was worse. 

We used fast switching,  and so the phases were all tied together. The
EVLA antennas showed an interesting phase slope at the end of the 
observation,
but not so dramatic that it precludes phase coherence between calibration
scans.  Attached is the phase plot.

cc




Mark Claussen wrote:

>>I'll try to have something to say about Q band before the day is over.
>>    
>>
>Well I didn't quite make it.  Here are some Q-band results from Jun 19 data.
>
>
>    A)  Overall. 
>
>An 18 was broken, as Ken reported.  An 24 does not have UX converter.
>There were fringes on all IFs for An 13, 14, and 16.
>
>I saw no dropouts in amplitude or phase, but again, none were
>expected.
>    
>    B) Returning to correct phase: 
>
>As with the K band observations, it was difficult to tell if the
>phases returned to correct values.
>
>
>    C) Bandpasses. 
>
>Antenna 14 has a spike near (but not exactly in) the center of the
>6.25 MHz band in IF D.  The baseband frequency at which it appears
>is about 3.5 MHz.  The spike is variable in strength but appears to 
>be there much of the time.  An 13, An 16, and An 14 (ABC) seem to 
>have reasonable bandpasses (as best as I can tell).
>
>    D)  Sensitivity. 
>
>AIPS weights were generated for all antennas and IFs. Sensitivities are
>estimated based on the aips weights.
>
>There was quite a spread in the AIPS weights for VLA/EVLA antennas.
>This is likely to be due to pointing, since the reference pointing
>was only done at X band (no double reference pointing).  The EVLA
>antennas are not significantly worse or better than VLA antennas, but
>this is a null statement.... nothing much can be said about the
>sensitivities based on this data.
>
>
>   E) System temperatures.   
>
>None of the EVLA antennas had reasonable Tsys recorded in the AIPS data
>(single digits).
>
>
>Mark
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>  
>

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