RE: [alma-sw-ssr] Offline and Pipeline Requirements

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

Hello Mark,

	I think it is good to clearly say this.

However, the image fidelity of ALMA in the submillimeter
will probably be comparable to BIMA at 3mm.

I would still like to see a comparison with running
the test in aips++ and any other packages capable
of handling the mosaiced data.

	cheers,

		Melvyn

> > 
> > Tim,
> > 
> > 	It's good to have your participation, and know what
> > to expect.
> > 
> > If there is a significant increase in image fidelity by
> > going back to the uv-data in the deconvolution of mosaiced
> > images, then this has a very significant effect on the operational
> > model for ALMA image analysis.
> > 
> > It remains to be demonstrated that there is a meaningful
> > increase in image fidelity with telescopes with real pointing
> > and other errors, and what the cost in performance is.
> > 
> > These tests should be done as soon as possible, and I would be happy
> > to provide some data. The attached MIRIAD script, takes
> > about 5 min to make images, 10 min for SDI and 20 min for Maxen
> > on a sun ultra 10 (93000 uv-points and 19 pointings and 64 channels).
> >  The numbers can be scaled appropriately for ALMA.
> > 
> > 		cheers,
> > 
> > 			Melvyn
> > 
> 
> 
> Mel,
> 
> I think the whole point is that we can't allow our experience with a 9
> element interferometer with maximum dynamic range of 200:1 to limit our
> understand of what is required of the data reduction on a 64 element
> interferometer which will potentially have a dynamic range of many
> thousands to one.
> 
> If there is any hope of correcting for pointing errors, it is through
> algorithms which combine pointing self-calibration with the deconvolution,
> ie, knowledge of the visibility data is directly tied together with the
> process of imaging and deconvolution.  This is the strength of AIPS++,
> and it will be somewhat difficult for less developed radio-synthesis
> software to deal with such problems and impossible for software such
> as IDL to deal with them.
> 
> 	-Mark
> 
> 
>