[vsnet-alert 63] EMERGENT Call for coordinated observation of UW Tri

[Daisaku Nogami <nogami@kusastro.kyoto-u.ac.jp>]

Dear Sir,

  As you might know, T. Vanmunster detected the second historical outburst
of UW Tri, which has been classified as a suspected nova.  However we
suspect that the object belongs to a rare group of CVs, called WZ Sge-type
stars.  WZ Sge-type stars are now thought to be extreme SU UMa-type dwarf
novae (for a model see Osaki, in recent PASJ), but too few established
members and too low outburst frequency have made both the observational and
theoretical study very difficult.  Observationally, in this case of UW Tri,
it is urgently requested to detect superhumps (semi-periodic modulation with
an amplitude of 0.1-0.3 mag, and a period a few percent longer than the
orbital period, i.e. 1.3-2.0 hours).  The Ouda team has embarked on a
systematic photometric research program of this object until at least
Mar. 20.  Unfortunately the visibility of this object is rather poor in
this season (only a few hours of continuous observation is possible from
one observatory).  So we would like to call for coordinated observations
to get better coverage, which is essential in uniquely determining the
period.

  The Ouda team has designed a continuous V-band CCD photometry with a
time resolution of 60 sec, just after the evening twilight until the
object become too low in altitude.  It would be a very difficult target,
but we would be very grateful if you join our campaign, in order to reveal
the nature of this enigmatic object, by taking the present special advantage
of long-awaited phenomenon in the exciting field of CVs.

  I am looking forward to hearing your good response.

Best regards,
Daisaku Nogami and Ouda Group

PS 1. The discovery report by T. Vanmunster is attached below.

1995 03 01.815 UT, [15.1 (T. Vanmunster, 0.35-m refl., seq: GSC);
     03 03.819 UT,  14.7 (T. Vanmunster);

PS 2. The finding chart by Duerbeck can be found in Space Sci. Review 45, 1

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