from:	Todd Hunter 
to:	jzhao@cfa.harvard.edu
cc:	Ray Blundell 
date:	Aug 17, 2018, 4:03 PM
subject:	Re: Fwd: Trying out pipeline reduction of SMA SWARM data in CASA

Todd Hunter 
	
Aug 17, 2018, 4:03 PM
	
to me, Ray
Hi Jun-Hui,
   Sorry for the delay, but I had not checked my harvard.edu email for a few weeks.
The contact person for CASA should be Bjorn Emonts who works here in Charlottesville.
bemonts@nrao.edu

I would also like to see more complete support for SMA in CASA, including getting the
SMA Tsys values loaded into the SYSCAL table of the measurement set, so that it can
be carried as a proper calibration table.  Taco had trouble with implementing
this part in sma2casa years ago, but since then there is now example function in
CASA how to do it.  I sent this info to Taco a few months before
he retired, I think he was preoccupied and never got around to it.

Regarding the coordinates, it is a tortured history.  I discovered in 2013
that the geocentric ITRF values for SMA had the sign of the Y value
flipped from convention of the other observatory entries.  I got that fixed
back that then (4.3 release, I believe), but the same problem returned in
recent releases.  But this issue did not affect imaging of data from sma2casa,
because the correct UVW values were already present, and
the imaging tasks (clean/tclean) use the lat/long/height when doing velocity
corrections, and *those* values for SMA had been correct up until the 5.3 release. 
In the 5.3 release, the sign of Y got fixed again but the height got changed
because there was a misunderstanding about whether height was w.r.t. geocenter
or the mean surface level.  I am partly to blame, but the
entries for other telescopes in that file are not consistent in this respect.
Anyway, I think the height is currently wrong, but have not had time to prove it.
I opened a ticket for investigating it earlier this year.  It would require
imaging a several hour track on a narrow-line source with the height set
one way, and then again with it set the other way.

Todd




On 08/17/2018 02:36 PM, Hunter, Todd R. wrote: