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THE ASTRONOMER Electronic Circular No 2492      2008 Oct 20 06.47UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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V1251 CYGNI
Hubert Hautecler and Eddy Muyllaert report a rare outburst of the dwarf 
nova V1251 Cyg. The last reported outburst was in 1997.

2008 Oct 17.79, <17.0 (J. Pietz, Germany)
2008 Oct 18.79, <16.1 (Gary Poyner, Birmingham England)
2008 Oct 18.84,  16.9C(Pietz)
2008 Oct 19.83, <14.6 (Eddy Muyllaert, Ostend, Belgium)
2008 Oct 19.83,  12.4 (H. Hautecler, Belgium)
2008 Oct 19.86,  12.5 (Muyllaert)
2008 Oct 19.88,  12.7C(Pietz)

V1251 Cyg is located at RA: 21 40 54.40 , Dec: +48 39 43.0 (J2000)

Charts for V1251 Cyg may be plotted using the AAVSO VSP facility at:
http://www.aavso.org/observing/charts/vsp/index.html?pickname=V1251%20Cy

Gary Poyner adds:
The last outburst occurred on Sep 7 1997 (Poyner/Kinnunen), when it also 
showed a short lived re-brightening event.  This object should be 
treated as a priority target, with visual and time series taken at every 
opportunity.

VSNET-Alert 10597:
As reported by a number of observers, the SU UMa-type dwarf nova
V1251 Cyg is undergoing one of its rare outburst. As it is high in the 
northern sky, it is unlikely many outbursts have been missed.

The last confirmed outburst (superoutburst) was in 1997 Sep., when the 
object reached a relatively faint maximum (mag 13.3). The object 
underwent a similar faint superoutburst in 1994 Dec. - 1995 Jan. 
(superhumps were confirmed). The earlier (first-ever outburst since its 
discovery as a potential nova) outburst was in 1991 Oct., when then 
object underwent a bright outburst similar to the current, and the 
discovery in 1963 (cf. IAUC 5377; IBVS 123, IBVS 3689).  The observation 
of the 1991 superoutburst is detailed in IBVS 4152.

The outburst properties and development of superhumps were unusual for 
an SU UMa-type dwarf nova with a superhump period of 0.07604 d (large 
outburst amplitude, rare outbursts, no or rare normal outbursts, 
relatively slow development of superhumps).  These properties may 
suggest that V1251 Cyg behaves as if it is the longest-Psh analog of WZ 
Sge-type dwarf novae (see also PASJ 53, 1191, "HV Vir and WZ Sge-Type 
Dwarf Novae").

Guy M Hurst