Re: [alma-sw-ssr] Pipeline Requirements new version

[mel wright 456 <wright@astron.berkeley.edu>]

All, and hardware guys too,


Another thought about antenna phasing.
The "standard" model is a combination of WVR monitoring,
and rapid switching to nearby phase calibrators.

Some variations on this:

1. At the lower
frequencies, there may be a sufficiently strong compact
source within the primary beam which could be used as
a continuous atmospheric phase monitor. The pipeline
could derive the antenna phases.

2. At high frequencies, a suitable monitoring source
may be found in the offset beam corresponding
to a low frequency band. These
offset beams move w.r.t. the target source, so the
monitoring source will change with time, but one
is only interested the phase, not the source.
The simultaneous observation of the target at
high frequency and a monitoring source in an offset beam
at low frequency  requires  a few things, like
2 active receivers, sharing bandwidth and correlator,
but has the advantage of a continuous phase calibration
on a nearby source.

3. If one uses different frequencies for the target and phase calibrator,
then a calibration of the phase offset between the 2 bands is required
at an interval determined by the phase stability of the system. A
stronger calibrator can be used for this. The pipeline should
keep track of this phase offset, its interpolation and the
calibration interval required.

4. Suitable phase calibrators could be found from a quick
mosaic around the target source at the start of an observation
 This is a job for the pipeline too.