(Light curve of AL Com superoutburst 2001. The magnitude scale is adjusted to that of Kyoto system. (preliminary result))
(Light curve of AL Com superoutburst 2001. The magnitude scale is adjusted
to that of Kyoto system. (preliminary result))
AL Com appears to be visible tonight,
COMAL 20010518.51 13.4
RASNZ Chart
25cm Newtonian 180X.
Regards,
Steve Kerr - RASNZ = Kf
Rockhampton,
Queensland
Australia.
(Combined CCD image of AL Com obtained at Brno by P. Sobotka and R. Novak)
(CCD images of AL Com on May 18, 19 and 20 by the Kyoto team with 25-cm
Schmidt-Cassegrain telescope + SBIG ST-7 CCD camera)
As Steve Kerr reported in [vsnet-outburst 2251], the WZ Sge-type dwarf nova
AL Com is undergoing a rare outburst ( ~13.3mag). The last outburst of AL Com
was observed in 1995 April. We started the observation of this object at
16:00 May 18 (UT).
Follow-up time-series observations are strongly encouraged.
Regards,
VSNET Collaboration team
(Averaged early superhumps observed on May 19 by Kyoto team.)
(Averaged early superhumps observed on May 19, 20, 21, and 22 by VSNET
collaboration team.)
AL Com early superhumps are evolving!
Dear Colleagues,
A quick look at the partially analyzed data of May 19 (vsnet-alert 5897) shows that there is a clear signature of evolving early superhumps. The outburst is thus very likely a superoutburst of a WZ Sge-type dwarf nova caught at the earliest stage (probably the earliest ever observed). The amplitude of variation is still small. At the same time, the object is slowly fading. We will report later as the analysis becomes more complete.
Looking forward to hearing your successful observations!
Regards,
VSNET Collaboration team
AL Com early superhumps and decline
Dear Colleagues,
More analysis (still ongoing) of the May 19 data has revealed the rapid fading at a rate of 0.80 mag/d. Early superhumps are present, as already reported. The best period from the presently available data is very slightly shorter than the orbital period, but the difference is marginally within errors of respective measurements. This observation may be the first indication of "negative superhumps" in the earliest stage of WZ Sge-type superoutburst. The full amplitude of early superhumps is 0.04-0.05 mag, and humps are singly peaked. This makes striking contrast to early superhumps observed in the 1995 superoutburst. This may be an indicatation that we are witnessing the earlier stage of evolution of these humps than in 1995. More detailed analysis will be later presented by Ishioka-san et al. Intensive observations are very encouraged.
Regards,
Taichi Kato
VSNET Collaboration team
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
(Left: growing superhumps observed on May 28. Right: averaged superhump profile during May 30 - June 2)
AL Com superhumps are growing!
Dear Colleagues,
The waited superhumps of AL Com are coming! The data on May 28 at
Kyoto clearly show the evolution of superhumps. More detailed analysis
will be presented by Ishioka-san and Uemura-san et al.
Regards,
VSNET Collaboration team
(CCD images taken at Kyoto on June 2 and June 11, showing the sudden fading of
AL Com (marked))
AL Com: rapidly decline!!
Dear colleagues,
Our yesterdays observation shows that AL Com is rapidly fading.
Its magnitude is ~16.7 mag. At 8 June, the object was still bright
at ~14.8 mag. So the decline rate during these three days is ~0.6 mag/day
(before 8 June, the decline rate was ~0.1 mag/day).
AL Com was 14.7 at 10.949 June (UT) in the report of visual observations
from Gary Poyner. Probably, the rapid decline occured during 10.949 and
11.5 (UT): 24 dars after the onset of the current outburst. In the 1995
outburst, another long lasting outburst started following the rapid decline
28 days after the the onset of the outburst.
More observations in this phase are strongly needed.
Regards,
Ryoko Ishioka
VSNET Collaboration team
AL Com rapid recovery again!
The short duration of the temporary fading strongly suggests that the object is entering a stage of the second superoutburst (if it follows the course of the 1995 superoutburst). Observations at this stage is extremely important. Please make time-resolved photometry as long as possible.
Regards,
VSNET Collaboration team
From: Jochen.Pietz@t-online.de (Jochen Pietz)
Subject: [vsnet-campaign-dn 900] RE: AL Com: rapidly decline!!
Results from the last two nights:
2001-06-12.879 17.0C:
2001-06-13.883 15.5C
Regards,
Jochen Pietz
VSNET Campaign News about AL Com
VSNET AL Com page
The 1995 super outburst
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