[vsnet-alert 1835] Re: on V2051 Oph (Warner)

[Taichi Kato <tkato>]

Brian Warner wrote:

> Dear VS Net persons:   I have been looking at your announcement of the
> supposed superoutburst of V2051 Oph.   If you look at my paper in MNRAS
> Vol 224, p.733,1987  you will see that I did some high speed photometry of
> V2501 in outburst and that (a) it is probably too small an amplitude to be
> a superoutburst and (b) there are no superhumps.  The eclipse centred on a
> "superhump" shown on your Web page is just the enhanced orbital hump that
> appears during outburst,
>    I do not understand just what is going on during an outburst of V2501;
> I hope that more extensive coverage will provide some clues.

   Yes, I had read your MNRAS paper; as I had previously discussed with
Rod Stubbings regarding the present event, your observations on 1984 May
4 - 8 may represent the final fading stage of a possible superoutburst,
though your high-speed photometry on the second and third nights failed to
show apparent superhumps (there seems some hint in May 4 data -- quite
unfortunate the run was too short).  In addition to Jensen's light curve
on our Web page, we have received three nights' CCD data from Kiyota-san
(posted to vsnet-obs).  The analysis of Kiyota-san's observations has shown
the existence of superhumps with a period of 0.0642 d, and an mean amplitude
of 0.4 mag.  Jensen's observation on the Web is clearly in line with this
result of analysis, and we have thus concluded he detected an eclipse
superimposed on a superhump.  I have just heard Matsumoto-san, at the Osaka
Kyoiku University telescope, successfully detected similar humps, which
ware clearly offset from the eclipse center (as Jensen observed) -- I hope
he may report further on this list.  Humps are apparently monotonously
shifting with respect to the eclipse phase.  This is the very signature of
the superhump in eclipsing SU UMa stars.

   Regarding the superoutburst amplitudes, the present outburst is nearly
1.5 mag brighter than usually observed outbursts (now many of them are
caught by the efforts of, esp. Rod Stubbings).  The observed amplitude
and duration (at least 10 days) naturally warrant the superoutburst
character.

Regards,
Taichi Kato

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