[vsnet-chat 3817] GK Per period analysis (re : analyses of visual observations)

[Taichi Kato <tkato>]

GK Per period analysis (re : analyses of visual observations)

> It would be interesting if, using your techniques, you could recover the
> orbital period of this object from that data for the epochs of quiescence.
> 
> I managed such once with less extensive BAAVSS data for this object, but
> was unable to ascertain whether or not the asymmetric nature of the folded
> lightcurve was meaningful or not.

    I just did the analysis, using visual observations reported to VSNET.
A total of 2425 observations between 1994 July 16 and 2000 November 26
(disregarding the outburst parts) were used.

    The PDM analysis show the clear presence of the periodicity related
to the orbital motion.  The best period determined from these visual
observations is 1.99673 d, which is close to the published spectroscopic
period 1.996803 +/- 0.000007 d (Crampton et al. 1996, ApJ 300, 788).

    http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/Novae/GK_Per/pdm.gif

    The phase-averaged light curve using Crampton et al.'s period and
phase (the zero phase is defined as the inferior conjunction of the
secondary) clearly shows doubly humped profile, which could be interpreted
as the ellipsoidal variation (or some sort of disk asymmetry?)

    http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/Novae/GK_Per/ph.gif

    There seems to be a finite positive O-C to Crampton et al.'s ephemeris.
The expected eclipse at phase zero was not apparent.

Regards,
Taichi Kato

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