[vsnet-chat 1751] Re: [vsnet-alert 2821] U Gem in outburst

[Taichi Kato <tkato>]

Re: [vsnet-chat 1748] Re: [vsnet-alert 2821] U Gem in outburst

Dear Lew,

> HOW high speed - is an integration time of several
> seconds to a minute going to give any information?

   During the 1998 December outburst of U Gem, we obtained time series
with a time resolution of 13 sec (10 sec exposure and 3 sec readout).
The result was quite satisifactory in detecting eclipses.  Time resolutions
with ten to several tens of seconds will be sufficient to depict
eclipses, but you may need several second if you wish to detect dwarf
nova oscillations DNOs -- will be a challenge for CCDs.

> I recall that the eclipses essentially disappeared in
> U Gem in outburst - that is correct, right?

   From our observations in December, eclipses are detectable (more than
0.1 mag deep) until the rise+2 days, when eclipses look almost disappearing,
but they reappear within days and become prominent as the outburst faded.
During the very rise of the outburst (at mag 10-11), although the stage
already ended for the present outburst, the eclipse was even detectable by
visual observation (T. Watanabe succeeded in this observation).

   Although U Gem is not included, light curves at our website may be of
additional help:

   http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/ippeg.html
   http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/htcas.html

   and links therein.

Regards,
Taichi Kato

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