A SEARCH FOR FAINT BLUE STARLIKE OBJECTS IN THE CENTRAL PART OF THE ERROR REGION OF THE JUNE 13, 1979, GAMMA-RAY BURST

Single compact objects of a neutron-star type in the solar neighborhoo d with a finite, nonzero surface temperature are potential sources of gamma-ray bursts (GRBs). Within the framework of this hypothesis, a me thod of searching for an appropriate optical candidate in the error re gion of an energetic GRB is considered. A 120 '' x 80 '' area of the s ky that includes the central part of the gamma-ray error box of GRB790 613 is studied in the B, V and R bands. The B-V and V-R colors were me asured for 263 sources with a signal-to-noise ratio (S/N) > 4 up to ma gnitudes B less than or similar to 26.(m)2, V less than or similar to 25.(m)7, and R less than or similar to 25.(m)2. There are no blue (in the two color indices) objects up to B approximate to 25(m) near the c enter of the gamma-ray error box, which can be interpreted as the abse nce of a compact object with a temperature in the range (0.5-1.5) x 10 (5) K in this direction to distances as large as 20-40 pc. Optical and X-ray data are used to place a possible general upper limit, T-lim < 1.8 x 10(5) K, on the temperature of the putative compact objects in t he vicinity of the Sun. The study of blue (B-V < 0) objects in the gam ma-ray error box of GRB790613, the smallest in the northern sky, using the results of searches for point sources in the soft X-ray band in t he error regions of bright GRBs, does not rule out the existence of su ch ''cool'' (T less than or similar to 10(5) K) objects, These objects could contribute significantly to the observed density of hidden mass not far From the Sun, and some of them could be associated with the n earest GRB sources.