[vsnet-alert 2129] Re: V793 Cyg

[Taichi Kato <tkato>]

Re: [vsnet-alert 2128] V793 Cyg

   Congratulations to Timo again!

>   There is however some unavoidable uncertainty:
> the star lies in a crowd of mag 15 stars, and the current
> astrometry is not very precise. So I would love a sharp
> CCD image and/or improved astrometry of this star (asap).

   The coordinates of V793 Cyg looks fairly well determined by the effort
of the Vatican team (the discoverer).  There would be no problem in confusing
between neibouring 15-mag stars.  The problem is the faintness of the
quiescence, which has hindered accurate astrometry using the POSS.
Accurate astrometry to sub-arcsec order is very valuable.  No outburst
have been yet reported to VSNET before this.

   According to the discovery paper, V793 Cyg (= VV 62), showed rather
infrequent outbrusts, the duty cycle (system above mag 15.0pg) is around 7%.

   Outbursts recorded:

     JD     mpg           duration
  2429107   15.1          isolated plate
    33330   14.8 (on 331) >2
    33717   14.5          two plates
    33739   15.9          continuation of 33717 outburst?
                          decline at a rate of 0.33 mag/d recorded
    34736   14.9          two plates
    34975   15.5          >2
    35788   14.4          two plates
    35809-814  15.4       similar to 33739; speed of decline 0.30 mag/d

  Though it is not clear the outbursts on 33739 and 35809 are related to the
20-day preceding ones, this object may tend to show such "double outbursts".
Considering the large outburst amplitude, this star will well deserve
follow-up time-resolved photometry.  Good target after observing V592 Her
for esp. northern observers.  We would love to hear any postive or negative
results.

Regards,
Taichi Kato

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