[vsnet-alert 538] No outburst of V1251 Cyg

[Taichi Kato <tkato>]

   AAVSO News Flash No. 56 tells a possible outburst of the SU UMa-type
dwarf nova V1251 Cyg.

> V1251 CYGNI
> 
> The dwarf nova type cataclysmic variable V1251 Cyg appears to be in outburst, > 
> as indicated by the following observations:
> 
>                      AAVSO Observer  
>     UT        Mag.     Initials      
> 
> SEP 05.854   <14.6       VMT     
> SEP 08.3457   14.3       NBY     

(AAVSO News Flash No. 56 extract)

   CCD images at Ouda Station, Kyoto University around Sep. 11.38 UT shows
the object at its usual minimum of V ~18-19 (unresolved triple).

   V1251 Cyg was discovered by Weber (1966), who reported an outburst
in 1963.  The nature and the quiescent identification, however, remained
uncertain for a long time.  Systematic visual monitoring of this variable
star by amateur astronomers started in 1980's.  After a long series of
negative observations, the star was finally caught in its second historical
outburst by M. Moriyama on 1991 Oct. 25.54 UT at mv=12.4 and by P. Schmeer
on 1991 Oct. 26.833 UT at mv=12.7 (Moriyama and Schmeer 1991, Korth 1991).
During the outburst, T. Kato discovered superhumps with a period of
0.07604 +/- 0.00010 day, confirming the object to be a member of SU UMa
stars.

   The next outburst was caught by G. Poyner and P. Schmeer on the closing
night of the year 1994.  This outburst was confirmed to be a superoutburst
of subsequent CCD photometry.

   Observers should be careful when identifying the object since V1251 Cyg
is erraneously marked on the atlas by Downes and Shara (1993).

Regards,
Taichi Kato

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