[vsnet-outburst 9564] V1251 Cyg: early superhumps? or growing stage of superhumps?

[Taichi Kato]

V1251 Cyg: early superhumps? or growing stage of superhumps?

   We have received the early data from Nakajima-san, Itoh-san,
and now from Gianluca Masi.  There have been reports of other
successful observations, and we expect to get further data soon.

   The data show a general decline (0.2 mag/d, faster than ordinary
SU UMa-type superoutbursts) and superimposed low-amplitude modulations
(0.03 mag in average).  The best period determined from the data is
0.0748(2) d, which is slightly shorter than the superhump period
(0.07604 d) recorded during the 1991 superoutburst.

   The present modulations may somehow reflect orbital period, but
the fractional superhump excess (1.7 %) appears to be too small
for this superhump period.  The profile is singly humped, with
faster rise than decline, suggesting that the present modulations are
growing superhumps rather than early superhumps or reflection-type
orbital humps.  The growth of ordinary superhumps has been slow,
as already pointed out during the 1991 superoutburst.

   Further observations are very strongly encouraged to follow the
evolution of superhumps, and to clarify the nature of present
modulations.

Please send your time-series photometry to:
vsnet-campaign-report at ooruri.kusastro.kyoto-u.ac.jp