This is an explanation for how the feeds are tested each week.

SRI runs a process called arrayhealth. Basically the correlator is used to observe a quasar for 3 minutes at each of these frequencies: 1040,3040,4500,6667,8400,10000 MHz. The results are store in /data/tumulus/obs/arrayhealth/2018-05-24_arrayhealth/ (but, actually named after the date).

A process called “COMPASS”, originally written by Karto Keating, is then run on these data and produces Tsys reports.

Also, all relevant data associated with the observing such as weather and the resulting tsys values, is placed in a file called obslog-1.

Elin wrote a program to read in obslog-1 and tell you what antenna pols are best to use at the frequencies observed in the array health run. The criteria it uses is tsys.

cd to ~/elin/arrayhealth/ah/lib
../progs/bestantpols.py -h (this will print out the help)
../progs/bestantpols.py --rflag --freq 1430 (prints out the best ant pols to use at 1430MHz)

Example

../progs/bestantpols.py --rflag --freq 1430
#Phase:	3c84-1430
#Attr:	['tsys-a', 'tsys-c']
#Run:	/data/tumulus/obs/arrayhealth/2018-05-24_arrayhealth/obslog-1
Ants: 2j,2b,1h,1f,1a,2d,4l,2f,5e,1b
Antpols: 2jy,2by,1hx,2bx,1fx,1ax,1ay,2dy,4ly,2fy,1fy,5ey,5ex,1bx

My experience has been that these are generally the feeds to use for beamformer observing.

Even though feeds may be deemed good to use by bestantpols.py, they may not be good in the beamformer. Here is an explanation:

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