[vsnet-chat 2619] Re: Tmz85

[aah@nofs.navy.mil]

Congratulations to the Kyoto group for getting a 12-hour
run -- that is 2+ hours longer than Joe Patterson got! :-)
  One of the reasons I offered to get a time series this
upcoming week was the two observations I obtained last
year.  CVs don't typically vary much when they are in
quiescence, yet my two measures showed a large variation.
My thoughts were that I was seeing eclipses, though the
chances of such an event are pretty low (in eclipse only
10percent of the time and only two data points).
  I respectfully disagree with Kato-san.  Most photometry packages
have problems when dealing with faint objects near
sky limit.  What he says holds only if there are no
systematics in the magnitude determination.  In general,
most photometry packages have systematic errors when measuring
faint objects, primarily due to the determination of
sky within the sky annulus.  I've found results to be
far superior by first combining images and then measuring
rather than the reverse.  If you don't have sufficient
signal, then you really can't get high time resolution.
Arne

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