(light curve by the Ouda team, Rudolf Novak, Lasse Teist Jensen, Lew Cook)
DV UMa outburst confirmed
Mr. Kinnunen reported that DV UMa, an eclipsing SU UMa-type dwarf nova, seemed to be undergoing an outburst ([vsnet-obs 25179]), and then, we started CCD photometry on 17:00, 8 Dec. (UT). and confirmed the outburst. The current magnitude is about 15 - 14.5 mag.
The follow-up observations are very urged.
YYMMDD(UT) mag observer 991120.124 <147 (G. Poyner) 991130.028 <144 (G. Poyner) 991130.060 <151 (T. Kinnunen) 991205.099 <155 (G. Poyner) 991205.910 <144 (T. Kinnunen) 991208.197 153: (T. Kinnunen)
Makoto Uemura and Taichi Kato
In the lightcurve of DV UMa on 8 Dec obtained from our observation at Kyoto, we detected eclipses of about 1 mag, whose profiles are gentler and shallower than that in the normal outburst in 1995 (eclipsing depth = 1.6 mag). We can also see variation like superhumps. These facts indicate DV UMa is undergoing a superoutburst.
We started tonight's observation on DV UMa on 12:00, 9 Dec (UT), and more than 7-hour observation will be possible. More observations at other sites are urged.
Makoto Uemura and Taichi Kato
DV UMa superhumps and eclipses
In the light curve of DV UMa observed on 9 Dec, three eclipses and three superhumps are detected. The eclipse profile is shallower (depth = 0.9mag) and has a larger width. Superhumps are clearly seen, and in addition, the piriod difference between that of superhump and eclipse (orbit) is clearly seen too.
It is confirmed that DV UMa is undergoing a superoutburst. More observations are urged.
Makoto Uemura, Taichi Kato
(light curve by Rudolf Novak and the Ouda team)
we observed DV UMa on October. 8 and detected two minima and two superhump maxima. There is clearly visible from light curve three modulations:
1) eclipses of acretion disk 2) (super)hump modulations 3) linear rise to maximum.
I think we covered very "young" phase of superoutburst and detected only grow of superhumps. Similar case was one run on T Leo udring last outburst when we saw rising modulation on light curve during our coverage.
To all who are interested in DV UMa system I'd like to recomend an article published by S. Howel and S. Blanton - "A photometric Analysis of ..." in AJ (106, 1, p.311) available free of charge from ADS.
Nicholas Copernicus Observatory in Brno. CR
P.S. Page of DV UMa's run from 1997 obtained here in Brno are on CBA Brno
home page at
DV UMa eclipse and superhumps (update)
(cf. vsnet-alert 3796, 3801, 3803)
Preliminary analysis of the Dec. 10 observations ay Kyoto (M. Uemura and T. Kato) shows a remarkable growth of eclipses. In contrast to shallow (0.9 mag) eclipses, we observed deep (up to 1.6 mag) eclipses as were observed during the 1997 superoutburst. The observation, together with Novak's most important coverage of the rising stage (Dec. 8), clearly demonstrates the quick evolution of the accretion disk during the early stage of the rare superoutburst in this interesting SU UMa-type dwarf nova. More information and the new superhump period will be issued later by Uemura-san.
Taichi Kato, Makoto Uemura, Rudolf Novak
CBA California - Lew Cook (COO) JD 2451523.9-2451524.1 Sawtoothed shaped superhumps at period 0.089 day (PDM/AVE) Superhumps amplitude (max - min outside of eclipse) 0.6 magnitude Eclipse depth 1.1 magnitude. Plot posted at http://www.geocities.com/lcoo/dvuma523.gif
===== Regards, Lew http://www.geocities.com/lcoo/(vsnet-alert 3813)
A clearing in the weather (temporary unfortunately!) allowed about 4 hours of coverage on DV U Ma. Light curve shows deep eclipses and very prominant superhump during the morning of DEC 11(JD 2451523)
Light curve visible at:
The 1997 April superoutburst
Detection of superhump (1997)
HT Cas (related system)
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