The 1999 Superoutburst of DV UMa

Successful international collaboration ongoing!

(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)

Regards,
Makoto Uemura and Taichi Kato

(vsnet-alert 3796)

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.

Regards,
Makoto Uemura and Taichi Kato

(vsnet-alert 3801)

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.

Regards,
Makoto Uemura, Taichi Kato

(vsnet-alert 3803)

(light curve by Rudolf Novak and the Ouda team)

Dear colleagues,

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. Howell and S. Blanton - "A photometric Analysis of ..." in AJ (106, 1, p.311) available free of charge from ADS.

Regards

Rudolf Novak
Nicholas Copernicus Observatory in Brno. CR

(vsnet-alert 3811)

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.

Regards,
Taichi Kato, Makoto Uemura, Rudolf Novak

(vsnet-alert 3812)

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)

Greetings

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:
http://www.kingsu.ab.ca/%7Ebrian/astro/cba_alta/data_archive/dvuma/dvuma121199.gif

Regards

Brian Martin
CBA Alberta