There has been some recent work on the problem of finding viable amplitude calibration sources which will allow ALMA to meet its absolute amplitude calibration specification. See the amplitude calibration source wiki page for further information. Specifically:
Recent work by Martin Cohen of UC Berkeley has led to a renewed focus on the potential for giant stars as flux calibration standards.
Extrapolation into mm could be as good as extrapolation into the MIR.
Gamma Crux studies recently and found to be RJ.
Stars which are RJ at 90 GHz will have to be RJ in the submillimeter.
Uncertainty in MIR (4-21 micron) range 1%.
Bryan: Should include Mars in measurements to tie to known standard.
Stuartt Corder: Try at 230 or 345 GHz due to system performance issues. Can do in next 2-3 months.
Bryan: Want to use EVLA to investigate star list. Martin will send target list to Bryan.
Mark Gurwell: Would like to try this at SMA. Martin will send target list to Mark.
Bryan updated us on characterization of the lower-frequency emission from planets and asteroids.
Bryan: Mars, Uranus, and Neptune at cm to long-mm wavelengths.
WMAP measurements is a starting point to compare with models.
Correction to Don Rudy's model to make fit work. Offset of a few percent.
Using Mars as fundamental calibrator for 10-50 GHz at EVLA.
Extending Uranus and Neptune to mm/submm/IR (Orton spearheading).
No recent work on studies of asteroids.
Mark Gurwell: Have been studying Ganymede and Callisto with SMA.
Tying to Uranus and Mars.
Usable at 5% level at least (relative to Uranus).
Also considering Titan.
Martin Cohen: What about Jupiter's influence on the icy satellite measurement from its strong emission via sidelobes? Interferometer smears this out. Does contribute but not strongly.
Ruediger Knessel: Asked what physics is not included in the extended Rudy model. Only dust storm physics is missing from the extended Rudy model.
Ancilliary Measurement Devices
Weather Station (P,T,RH,Ws,Wd) Instrumentation
No new information. Still waiting for site infrastructure.
Any comments from CSV on recent calibrator database development?
Ruediger: Prototype under development and testing. May be available in January for more complete testing.
Bryan: EVLA calibrator database ready. Will be available for outside querying soon. Bryan will keep us informed.
We are in the process of trying to use the calibrator database interactively from our observing scripts with the R8 release. If we cannot interface very cleanly with that we will fall back to the python flat file until we get something more meaningful/useful.
There is a test link if people want to play around with it that has been distributed within the JAO. It currently has a couple of bogus values in it for the handful of sources I have checked (J0006-063 has proper positions from one catalog but the position it recovers from the SMA is off by 10 degrees in dec).
Baltasar Vila-Vilaro is collecting comments to send back to the developers (they do not interface much with CSV directly as this is officially an obops tool).
Date of Next Phone Meeting
Tentative date for next ALMA Calibration Group telecon will be 2011, February 10th 15:00 UT.
-- JeffMangum - 2010-12-09