[vsnet-campaign 969] V478 Her

[Taichi Kato <tkato>]

V478 Her

   Message in vsnet-alert 5966, in response to vsnet-campaign 963.

From: "Tonny Vanmunster" <Tonny.Vanmunster@advalvas.be>
Date: Sat, 9 Jun 2001 17:49:18 -0000
Subject: [vsnet-alert 5966] V478 Her : very likely a new UGSU type dwarf nova
near the upper limit of the period gap

Dear colleagues,

On June 8th, 2001, the night was very clear over CBA Belgium Observatory, so
we decided to start an all-night long photometry session on V478 Her. The
resulting light curve covers about 3.7 hours and is presented on my web site
www.lunarpages.com/cbabelgium. It clearly shows a 0.33-mag modulation, that
very likely is to be attributed to superhumps, thus classifying V478 Her as
a new member of the UGSU-type dwarf novae. Due to the short nights in
Belgium, during this period of the year, we could not follow the variable
for a longer duration, but we hope that contributions from other
observatories will help in securing the classification of the variable.

Using Stellingwerf's PDM algorithm, we derived a preliminary superhump
period value of 0.129 +/- 0.005 d or about 3.1 hours. This puts V478 Her
near the upper limits of the so called 'period gap'.


Tonny Vanmunster
CBA Belgium Observatory
http://vsnet.lunarpages.com/cbabelgium
email : Tonny.Vanmunster@advalvas.be

  [vsnet-campaign 963]

   According to AAVSO News Flash No. 793, the recently identified
cataclysmic variable V478 Her may be brightening.
CCD observation by Diethelm recoreded the object at 15.70 on June 4.9599 UT.
The object had been regarded as an irregular variable (IS:) until
quite recently.  The reported range of variability if 15.5-17.1p.

   Confirmation of the brightening, and subsequent detailed observations
are very strongly encouraged.

   ===

   Since the amplitude of variation (15.5-17.1p) is relatively small for
an SU UMa-type dwarf nova, this object may be something like an active
NL-type star (like V795 Her), or may be like DW Cnc, which shows
low-amplitude dwarf nova-like outbursts and large-amplitude humps
(cf. vsnet-alert & campaign messages; Uemura et al., in preparation).
Confirmation of the period and the nature of brightening is highly wanted.

Regards,
Taichi Kato
VSNET Collaboration team

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