COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                      Number 2757

                                        Konkoly Observatory
                                        Budapest
                                        9 July 1985

                                        HU ISSN 0374 - 0676


           ON THE MEAN CYCLE-LENGTH OF THE U GEMINORUM
                      STAR VW VULPECULAE


  VW Vul has been suspected by Shafter (Inf.Bull.Variable Stars No. 2373 and
Astron.J. 90, 643) as being a U Geminorum star of SU Ursae Majoris type; he
also gave an estimate of the mean cycle-length of "roughly 30 days" (according
to Mattei, unpublished).
  Since its discovery by Wolf in 1904 (Astron.Nachr. 166, 77) and a few
estimates given by him (Astron.Nachr. 221, 261; 1924) no long-term photometric
observations have been published. Its probable nature as a cataclysmic variable
was not detected before 1978, when Bond (Publ.Astron.Soc.Pac. 90, 526) found
spectroscopic features.
  I therefore determined the brightness of VW Vul on 132 Sonneberg plates
taken with the 140/700 mm Triplet camera between 1930 and 1969 by the late
R. Brandt. On this material the star varied from 13.1m to>14.9m pg., exhibiting
the numerous "bright observations" typical for a medium-cycle U Geminorum
star: 27 observations show the star in the upper part of the eruptions down
to 0.6 mag below maximum light. At this level an average width of 4d+/-1d of
the outbursts can be deduced from the short series of the AFOEV (observer
Verdenet, Bull. 26; 27a-28; 30). With this, our material statistically yields
a mean cycle-length of about 19d+/-5d. That means that the findings of Mattei
and the AFOEV, from a comparatively very short time interval, are confirmed
by our 40 years' data, thus indicating a stable behaviour of the star.





                       W. WENZEL

                       Sternwarte Sonneberg
                       Zentralinstitut fur Astrophysik
                       der Akademie der Wissenschaften
                       der DDR