COMMISSIONS 27 AND 42 OF THE IAU
             INFORMATION BULLETIN ON VARIABLE STARS
                          Number 3883

                                            Konkoly Observatory
                                            Budapest
                                            20 May 1993

                                            HU ISSN 0374 - 0676


            A NEW CATACLYSMIC VARIABLE S 10930 IN LYRA


When blinking a pair of Sonneberg 400/1600 mm astrograph plates in the course
of the search for an optical counterpart of the BATSE gamma-ray burst source
920804 (19h53mUT) (Greiner, 1993) I detected a new U Geminorum type variable at
the following position (1950.0):

              alpha=18h59m58s, delta=+42d50.4'

On 597 exposures taken with the astrographs 40/1600 mm, 400/1900 mm, and
170/1200 mm in the years 1963 to 1992 mainly by R.  Brandt, L.  Meinunger and
G.  A.  Richter, I found 10 eruptions.  The star was brighter than 15.3m pg on
altogether 26 plates and in most cases invisible, much fainter than the quoted
value, on the remainder.

Observed maximum brightness:  13.2m pg, brightness estimated on the POSS I
prints:  18.0m (not conspicuously coloured).  List of observed eruptions:

Date of highest  Observed    Lower limit       Number of
brightness      maximum      of duration     eruption plates
       UT        pg
1970 June 2     15.4m                             2
1973 Sep. 1     13.3                              1
1983 June 10    14.7            5^d               6
1985 July 4     13.2            13                7
1986 Sep. 11    13.9                              1
1987 Oct. 1     13.5                              1
1988 Apr. 19*   15.2                              1
1988 July 10*   14.7            12                1**
1989 Oct. 4     13.4                              2
1992 Sep 17     14.0             5                4

Remarks: * fainter than 17.2m between the two 1988 dates
        ** one additional plate yields 15.5m at July 22

The pg magnitude system (see Figure 1) has been linked to the Mt.  Wilson
Selected Area 38.

The methods described by Wenzel and Richter (1986) or Richter (1986) for
statistically evaluating the mean cycle length concurrently yield 300+-50 days.
This value does not severely disagree with modern Kukarkin-Paregano
relationships, although it must be borne in mind that these statistical
considerations do not include possibly existing undetected short eruptions of
lower maximum brightness.


                              [FIGURE 1]


This work has been supported by funds of the German Bundesministerium fur
Forschung und Technologie under contract no.  05-5S0414.


  W. WENZEL
  Sternwarte
  D O-6400 Sonneberg
  Germany

References:

Greiner, J., 1993, unpublished
Richter, G. A., 1986, Astron. Nachr., 307, 221 [BIBCODE 1986AN....307..221R ]
Wenzel, W., Richter, G. A., 1986, Astron. Nachr., 307, 209 [BIBCODE 1986AN....307..209W ]