New Allen Telescope Array Development

Email from August 07, 2017 from Griffin:

> On Aug 7, 2017, at 7:48 AM, Griffin Foster <griffin.foster@gmail.com> wrote:
>
> Hi Jon,
>
> I really appreciate you taking your time to help Andrew and I check out the ATA. Your knowledge was invaluable, 
and we learned a lot. On the way back yesterday we had a chance to think about next steps in trying to use the ATA 
for astronomy, and hopefully, you are interested in being involved further.
>
> In my mind, the next step is to simplify the digital chain and look at individual antenna outputs. We can setup a 
fast-dump spectrometer using a SNAP board. Sampling at say 450 Msps, we could sample the entire analogue band. With 
a SNAP board, we could get 2 or 3 inputs, then output spectra over 10GbE to a capture machine.
>
> We should be able to see astronomical sources very easily with a single dish. The 21 cm line should pop-out very 
quickly when pointed at or near the galactic plane. The gain should change significantly between a bright A-team 
source (Cygnus A, Cassiopeia A, Taurus A) and basically any other sky position. We should be able to fold and 
detect a bright pulsar like B0329+54 very quickly.
>
> I would suggest the following plan:
>
> 1. You come out to Berkeley, and we setup a SNAP board design to output spectra, which you take back to the ATA.
> 2. Run the spectrometer on each antenna (both polarizations) to get diagnostics:
>     * Observe the galactic plane for a few minutes, tuned to around 1420 MHz. This is a good check to see that 
there is nothing wrong with the dish, you should always be able to see the 21 cm line.
>     * Observe an A-team source, on for 2 minutes, pointed 10 degrees away for 2 minutes, across the band, say 1 
GHz, 2 GHz, 4 GHz, 8 GHz. We can use this to measure the sensitivity (SEFD) of each dish.
>     * Observe pulsar B0329+54, B0531+21 or B0950+08 for 10 minutes at say 3 GHz, this is useful to show that 
there is sensitivity and that the time reference is working.
>     * Observe an A-team source by moving the dish across the source to see the flux increase, then drop off as a 
function of the antenna beam gain, at around 3 GHz. This is useful to show that the pointing makes sense and the 
beam looks correct.
> 3. You can either transfer the output data, or we can show you how to look at it to make sense of things. What 
  ever we find, we can then figure out how to fix things.
> 4. Once we figure out how to report the diagnostics, you can keep the SNAP board at the ATA to regularly do these 
checks.
>
> It would be exciting to get the ATA in a condition to do astronomy again. Let me know what you think of this, or if you have any questions/ideas.
>
> -Griffin