from:	Hauyu Baobab Liu 
to:	melvyn wright ,
Jun-Hui Zhao 
date:	Thu, Jan 5, 2017 at 7:02 AM
subject:	SMA SWARM full polarization observations towards Sgr A*

Dear Dr. Wright, Jun-Hui,


Happy New Year!

I was finally able to sneak into a workstation with large enough memory
to process the SMA observations taken on Aug. 20 and 21,
when others were in holidays.

The technical part of this project is exciting and encouraging,
while scientifically we don't see anything beyond what we already know yet.
The Aug. 21 observations had quite noisy phase due to weather.

Aug. 20 has detected polarization from Sgr A*.
There were eight available antennae,
and our mosaic observations around the CND essentially made on-axis and off-axis
observations for Sgr A*.
The off-axis effect seems not terrible,
although some anomalous phase errors (maybe just weather)
instead of the off-axis polarization may be yet dominating the errors.

The SWARM correlator seems to be subject to a not entirely antenna-based
cross rx phase offset.
Our calibration strategy did not allow use to remove this cross rx phase offset.
But this problem seems negligible among the Antennae 1-5 group.
After flagging out Antennae 6, 7, and 8,
the observations with SWARM give consistent results with the old ASIC correlator.

The observed polarization percentage and position angles are reasonably well consistent
with the earlier SMA observations, and our ALMA results.

Best wishes,
Baobab