[vsnet-campaign-news 64] AstroAlert: AL Com: impressive image and successful campaign

[Taichi Kato <tkato>]

      ****************************************************************
            Impressive Image and Successful Observing Campaign of
                          AL Comae Berenices
      ****************************************************************

    Rudolf Novak kindly sent an impressive image of outbursting AL Com 
obtained by him and Petr Sobotka.  The image clearly shows AL Com in
extremely rare outburst, against beutiful spirals of M88.  The image
truly qualifies AL Com as one of "variable stars of the year"!

    The image can be seen at the VSNET AL Com page shown below.

The message in [vsnet-campaign 920,921] written by M. Uemura:

   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

---

    We have updated the VSNET AL Com page. 
We have additionally presented the nightly fading trend during 
the superoutburst and the new double-peaked hump profile.

   http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/alcom0105.html

   We have been undertaking on photometric campaigns on several super-
outbursting dwarf novae and peculiar variable stars.  News and call for
observations on these objects will be issued on our regular weekly
"News from VSNET" bulletins.  Those who immediately need information
should make an access to the VSNET website, and click on VSNET campaign
list.

----------------------------------------------------------------------------

  VSNET (Variable Star Network) is an international variable star observing
network, covering various areas of novae, supernovae, cataclysmic variables
(CVs), X-ray transients, and other classical eruptive, pulsating, and
eclipsing variables.  VSNET is one of invited contributing organizations
to the SkyPub AstroAlert system.

       VSNET Home Page: http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/

CCD observations of such targets are a relatively easy task for a 20-40cm
telescope; simply take as many CCD frames (with exposure times 10-30 sec)
as possible, spanning several hours per night.  The only requirements are
the weather and your patience!  If you need more help on the observing
technique, please feel free to ask on the vsnet-campaign list.

   We would sincerely appreciate volunteers who would join the VSNET
Collaboration team to study the wonders of these exotic variable stars.
To join the VSNET campaign collaborative list, send an e-mail to

         vsnet-adm@kusastro.kyoto-u.ac.jp (VSNET administrator)

with a line "SUBSCRIBE vsnet-campaign." or your comment to join the
collaboration team.

----------------------------------------------------------------------------

VSNET Home Page

---

vsnet-adm@kusastro.kyoto-u.ac.jp

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp