[alma-config] Re: Imaging Simulations

[Simon Radford]

John,

Your results of your simulations should provoke some lively discussion.
A couple of points:

-- As Mark Holdaway has often pointed out to me, a centrally condensed
configuration, such as your spiral, requires more physical real estate
than a ring configuration for the same nominal resolution. If I read
your (proto-)memo correctly, you compared a 3 km spiral to a 1.5 km
ring. This is, of course, an important trade-off. Since the maximum
extent of the ALMA configurations is fixed (3 and 10 km) by various
constraints, the trade-off becomes higher resolution (uniform uv
illumination) vs. better overall imaging quality (Gaussian uv
illumination).

-- A corollary: What scientific problems require higher resolution at
the expense of overall imaging quality? Exoplanets, AGN cores, and
masers come to mind. Will different configurations have different
scientific specialties?

-- You make an analogy to the effective uv coverage of an optical
telescope. Another analogy is Single dish radio telescopes, which are
almost always illuminated with a Gaussian taper, at least at mm
wavelengths.

Simon

PS: In section 5, you speak of a "small *increase* in resolution" for
the long track observations because the east-west beam size increases to
147 mas from 135 mas. You mean *decrease* in resolution, don't you?