COMMISSIONS 27 AND 42 OF THE IAU
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 3882

                                            Konkoly Observatory
                                            Budapest
                                            20 May 1993

                                            HU ISSN 0374 - 0676


         UNSUCCESSFUL SEARCH FOR AN OPTICAL COUNTERPART
                      OF GRS 1915+105


The detection of a new X-ray "transient" in Aquila (first observation 1992 Aug.
15) by the Granat WATCH experiment was announced by Castro-Tirado et al.
(1992).  Shortly afterwards GRS 1915+105 was confirmed by the BATSE/Compton
Observatory team (Harmon et al.  1992) in the energy band 20-230 keV, also of
dates before the original discovery.  The source had remained at about 300mCrab
between 1992 mid-August and the end of September.

On 11 plates taken by E.  Splittgerber at the Sonneberg astrographs 400/1600 mm
and 1070 Sonneberg Sky Patrol exposures (limiting magnitude 12m to 15m pg)
gained from 1928 to 1992 mainly by P.  Ahnert, H.  Huth, and B.  Fuhrmann we
searched for an optical counterpart at the ROSAT position (Greiner 1993).

No optical transient, or enhancement of the image of an object, could be
detected within a circle of about 1' radius.  The threshold of the checked
astrograph plates are between 16.2m and 17.5m pg, the deepest plate being of
1992 Aug.  24.9.  By the way, these plates fill the gap in the material of
Castro-Tirado et al.  (1993).

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


                          W. WENZEL
                          E. SPLITTGERBER
                          Sternwarte
                          D O-6400 Sonneberg

                          J. GREINER
                          Max-Planck-Institut fur
                          Extraterrestrische Physik
                          D W-8046 Garching
                          Germany

References:

Castro-Tirado, A. J., et al., 1992, IAU Circ., 5590 [BIBCODE 1992IAUC.5590....2C ]
Castro-Tirado, A. J., et al., 1993, INTEGRAL Workshop Feb. 1993 at Les
   Diableres (paper submitted to Astrophys. J. Suppl.) [BIBCODE 1994ApJS...92..469C ]
Greiner, J., 1993, IAU Circ. in preparation [BIBCODE 1993IAUC.5786....1G ]
Harmon, B. A., et al., 1992, IAU Circ., 5619 [BIBCODE 1992IAUC.5619....2H ]