Detection of early superhumps in the rarely outbursting dwarf nova DV Dra

Patrick Schmeer, Germany reported his detection of a very rare outburst of the dwarf nova DV Dra on 2005, Nov 22nd, using the University of Iowa 0.37-m Rigel Telescope. The object was seen at mag 15.1 CR, while 3 nights earlier it was still below mag 18.0. The outburst was independently observed by Tim Parson, Forest Lake, MN.

Schmeer's observation is only the second recorded outburst of DV Dra. Its first one was a superoutburst in June 1984, when the star reached photographic magnitude 15.1 (IBVS No. 3626). No outbursts are recorded in the AAVSO International Database since DV Dra was added in 1994. 

Detection of early superhumps at CBA Belgium Observatory

I started an unfiltered CCD photometry session on DV Dra at 18h20m UT, Nov 22, 2005, using a 0.35-m f/6.3 telescope and ST-7XME CCD. The session lasted for nearly 200 minutes and had to be interrupted because of clouds. 

DV Dra - unfiltered observations at CBA Belgium Observatory on 2005, Nov 22/23

The resulting light curve is shown below. It clearly shows early superhumps (double-peaked), with an amplitude of 0.2 mag. A period analysis using Peranso's ANOVA method yields a superhump period of 0.061 +/- 0.002 d (see figures below). DV Dra therefore is now firmly established as a new UGSU-type dwarf nova, and almost certainly belongs to the class of UGWZ objects. Early superhumps are commonly seen in UGWZ-type dwarf novae, during the initial stage of the outburst.

The object was around mag 15.5 unfiltered. 

Follow-up observations are of utmost importance. 





Copyright © 2005 - Tonny Vanmunster.