[mmaimcal] SMA as the ACA

[Simon Radford]

So Smithsonian, which was too timid to go to Chile in 1990, now wants to get on the ALMA bandwagon. Has the SMA actually produced a scientific observation? Quick, before it does, let's disassemble it and ship it to Chile where it will lose all independent
identity and become an auxillary cog. And this will save money?

The SMA collecting area is  8 x pi/4 * 6^2 = 226 m^2.
The ACA collecting area is 13 x pi/4 x 7^2 = 500 m^2. 
So the calibration and sensitivity issues that worry us about the ACA will be twice as bad with the SMA.

The 'pointing [is] 1" but not quite there yet.' The ALMA (ACA) spec is 0.6", so again, the SMA falls short by (almost) a factor of two.

Other than the antennas, what parts of the SMA would be used for the ACA substitute?
 -- correlator? Unlikely, if the advance correlator folks go ahead.
 -- receivers?  Unlikely, if we want uniform packages, etc.
 -- mixers?     Perhpas, if repackaged.
 -- software?   Unlikely, if we want uniform operation.
 -- lo/if etc.? Unlikely, if we want ACA/ALMA interoperation.
 -- infrastructure? Unlikely, since not very portable.
So we're left with the desks and filing cabinets.

Simon