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

[Robert Lucas <lucas@iram.fr>]

mel wright 456 wrote:
> 
> 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.

Agreed. We had this before (6.3-R6) in sw memo 11. Self Cal should be
mentioned in the new reqs.

> 
> 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.
 
I agree with the other replies that this appears  now excluded by
hardware design; it seems to me  unlikely in any case  that there are
enough sources to do that kind of calibration in a significant number of
projects. 


> 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.

This also is mentioned in our Observing Modes Use Cases and in the
OffLine Reqs.
OL 4.2 R4; it should be mentioned in the piline reqs.
 
> 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.

I'm not sure the pipeline reqs are at this level of detail yet (as there
is no very specific data processing here). Thi sis more at the
`observing mode' level.

Robert








-- 
Robert LUCAS,            Institut de Radioastronomie Millimetrique
300 rue de la Piscine,  F-38406 St Martin d'Heres Cedex   (FRANCE)
Tel +33 (0)4 76 82 49 42                  Fax +33 (0)4 76 51 59 38 
E-mail: mailto:lucas@iram.fr                http://iram.fr/~lucas/