Return to Home Page
>> I generally don't consider 2arcsec as a "small systematic difference".
>> ...high airmass...a more likely problem is differential refraction...
It seems to me that this would be relatively small and to first order
ought to be taken out by the astrometric solution, especially since
the field is small. What I was wondering was what Berto's software was
actually doing---a simple linear fit might not be sufficient, or maybe
other subtle problems. One way to test of course is to take several
frames with the target in different parts of the frame so that you get
different reference stars on each. If taken back-to-back the results
should all be very similar, and the scatter on say three or four such
frames will give you a much better idea of the real uncertainty on the
position than just the internal error of the fit.
\Brian
Return to the Powerful Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
