[vsnet-chat 2503] Re: QY Per

[Taichi Kato <tkato>]

Re: [vsnet-chat 2502] Re: QY Per

Dear Arne,

>   You also are improving your photometric accuracy.
> However, most amateurs are still using unfiltered
> CCDs.  This may be to get the most photons, but limits
> the ability to combine datasets.  I'd really, really
> like to see the active observatories pick a common
> filter for the coordinated campaigns.

   Yes, it's completely true if observers are equipped with 40-cm (or larger)
telescopes and more sensitive CCDs.  It would be (or has been known to be)
a hard job for a 25-cm telescope to get filtered time-series photometry of
a 15-mag star.  For such a faint object, unfiltered photometry is probably
the optimal strategy.  The color variation during the superhump cycle
is known to be small for red lights, so it can be neglected as the first
approximation.
   In order to reduce the effect of the large color terms and the atmospheric
extinction, we should recommend to use a blue comparison star.  In selecting
the comparison, your field photometry has been quite helpful!

Regards,
Taichi Kato

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