COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                      Number 3143


                                       Konkoly Observatory
                                       Budapest
                                       5 February 1988

                                       HU ISSN 0374-0676


         A POSSIBLE VARIABLE STAR INSIDE THE ERROR BOX
                      OF GRBS 790331


   A possible unknown variable star has been found inside the error box of
the gamma-ray burst source 790331 (Laros et al., 1985).
   The faint star at RA =19h 25m 25.4s(+-1.3s), delta =+03 35'40"(+-20")(1950.0)
having normally mpg ~ 15.7 shows increased brightness at mpg ~ 14.6 on the plate
taken by the 40 cm astrograph at the Sonneberg Observatory of the Central
Astrophysical Institute of the Academy of Sciences of the GDR on July 26, 1962
(JD 243 7872.468). The plates taken by the same instrument ~ 1 h before and
~ 2 d after show the star at the normal, fainter light.



                               [FIGURE 1]

 Figure 1: Finding chart for the suspected variable star. Size of the frame
           represents 9x6 arcmin^2.


  The investigation of this star using more than 400 astrograph plates from
the Sonneberg collection has revealed no other brightening in the time interval
1928 - 1987, although low-amplitude (~0.3 - 0.4 mag,) magnitude variations 
cannot be ruled out. The examination of the POSS prints has revealed no remarkable
color of the star.

  More optical data are needed to confirm the variability found, to make a
classification of this suspected variable star and to clarify the possible 
relation to the GRBS 790331.




                         R. HUDEC
                         Astronomical Institute
                         251 65 Ondrejov
                         Czechoslovakia





Reference:
Laros J.G. et al.: 1985, Ap. J. 290, 728. [BIBCODE 1985ApJ...290..728L ]