[evlatests] Q-band holography d.d. 2011-10-29

[Keith Morris]

A temperature sensor located with the room-temperature receiver 
components  shows a monotonic increase in temperature of about 5 - 6 
degrees C during that time.

We are doing some investigation into the gain sensitivity to temperature 
change for these components.



Michiel Brentjens wrote:
> ** [2011-10-31 Mon 12:11] Q-band holography d.d. 2011-10-29
> 
> Temperature sensitive gains?
> ----------------------------
> 
> A 3C273 Q-band holography observation from past Saturday shows a
> systematic decrease of PDIF over the course of six hours in virtually
> all antennas. This *decrease* in accompanied by a similar slow,
> systematic *decrease* in visibility amplitude. Typically, PDIF
> decreases by 20%. The visibility amplitudes also show a 20% decrease,
> although they are much noisier than the PDIFs.
> 
> The source had a fairly constant elevation between 36 and 57
> degrees. The observation began at 08:00 MDT and ended at 14:00
> MDT. Are we seeing a temperature dependent Q-band gain here? Notable
> exception is IF 3C, which shows nicely constant PDIFs, yet also
> decreases its amplitudes along with all others.
> 
> 
> Other phenomena
> ---------------
> 
> For some reason, 11R lost all signal around 16:50 UTC. After 17:30
> UTC, the PDIFs of 20L become increasingly more noisy, until they
> suddenly snap together at a higher value around 19:05 UTC. 12A PDIFs
> are consistent with noise. 4L PDIFs behave nicely until 17:00, at
> which point they increase by 50% and begin behaving erratically.
> 
> - Michiel
> _______________________________________________
> evlatests mailing list
> evlatests at listmgr.cv.nrao.edu
> http://listmgr.cv.nrao.edu/mailman/listinfo/evlatests

-- 
Keith Morris
National Radio Astronomy Observatory
1003 Lopezville Rd.
Socorro, NM 87801
575-835-7060 (phone)
575-835-7027 (fax)