Re: Interesting paper

[Andrew Bennett <andrew.bennett@ns.sympatico.ca>]

On Fri, 04 Feb 2005 17:24:17 -0600,Michael Sallman
<msallman@pro-ns.net> wrote:

>Thought this might be of interest:
>http://arxiv.org/astro-ph/0502056

I have read this through once, quickly and a couple
of points stick out.

First, their airmass is a function of image only so their
images must be a great deal smaller than 4 degrees!
At the same time, their image position is a function of
star number only. I am not sure to what extent the 
method itself is limited to small image size and
perfect image registration.

Second, there is no discussion that I can find as to how
they select the sigma_ij, that is the uncertainty in each
individual star measurement. In the TASS data set,
this varies by order of magnitude for the same star
between different images and estimating it is the
principal problem to be solved ...

Andrew Bennett, Avondale Vineyard, NS, Canada