[vsnet-alert 5214] V405 Vul = S10943 = RX J1953.1+2115 is new UGSU-type dwarf nova with second-longest superhump period

["Tonny Vanmunster" <Tonny.Vanmunster@advalvas.be>]

Dear all,

We have obtained CCD photometry time-series data on V405 Vul = S10943 at CBA Belgium Observatory, on Aug 25/26, 2000 and Aug 26/27. The resulting light curve clearly shows periodic modulations associated with superhumps. A period analysis, PDM based, yields a superhump period of 0.1205 +/- 0.0019 d and a full superhump amplitude of 0.19 mag. 

Our observations thus firmly establish V405 Vul as a genuine SU UMa type variable. The SU UMa classification of V405 Vul was suggested by Richter et al. in IBVS 4622, based on archival material obtained at Sonneberg Observatory. In addition, our findings confirm V405 Vul as an SU UMa dwarf nova with the second-longest superhump period, and very close to the upper border of the period gap. Only TU Men is known to have a longer superhump period (0.1262 d).

We probably observed V405 Vul near the end of a superoutburst. Our Aug 26/27 observations already showed a slight fading of the object. Nevertheless, it would be interesting to continue monitoring the present outburst through CCD photometry and other means. Please note that I will probably be clouded out for the next couple of nights, so any assistance from other observatories would be highly appreciated. Needless to say that additional datasets will allow us to further refine the superhump period value.

With kind regards,
Tonny Vanmunster
CBA Belgium Observatory

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