[vsnet-campaign 920] AL Com: preliminary analysis

[Makoto Uemura <uemura@kusastro.kyoto-u.ac.jp>]

Dear Colleagues,

   Combined the data kindly sent to the VSNET collaboration team 
(vsnet-campaign 918), we have performed preliminary analysis of 
these early obsevations.

   We performed period analysis using May 19 data (the Kyoto team 
and the R. Novak & P. Sobotka) and May 20 data (the Kyoto team),
and obtained the best candidate of the period of early superhumps 
of 0.05673 (8) d which is consistent with the orbital period within 
its error.  The profile has double peaks (~0.1mag) per one period.  
The light curve by R. Novak and P. Sobotka clearly shows this feature.  
The double-peak profile can be also sometimes seen in the Kyoto data, 
but not constantly.  This may imply that the amplitude of these humps 
are variable.

   The light curve on May 20 taken by R. Novak & P. Sobotka shows 
a relatively large (~0.2mag) hump with a single peak.  The phase of 
this peak is quite different from that of earlier humps, so we should 
consider these have an essentially different nature.  According to 
the light curve on May 21 by Gary W. Billings and R. Novak & P. Sobotka, 
this large hump seems to be diminished and the light curve has become 
more smooth, and no prompt periodic variations are not seen. 

   The object is now gradually faded with 0.08mag/d.  We will see 
the evolution of normal superhumps within these days, so follow-up 
obsevations are strongly urged.

Regards,
M. Uemura, R. Ishioka, T. Kato, R. Novak, P. Sobotka, and G. W. Billings
on behalf of the VSNET AL Com collaboration team

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