X-RAY OBSERVATIONS OF 4U 1700-377 HD 153919 AT 35-1300 KEV BY THE SIGMA TELESCOPE OF THE GRANAT OBSERVATORY/

From 1990 to 1992, 4U 1700-377 was in the field of view of the SIGMA t elescope for 15 observing sessions. On 12 September 1990, strong varia bility of the hard x-ray flux of this source was detected. During the most powerful burst, the source flux increased by a factor of approxim ately 10 over approximately 6000 sec. On 27 September 1990, variabilit y of the x-ray flux was observed with a quasiperiod of approximately 5 4 h. Approximating the spectrum of 4U 1700-377 by a bremsstrahlung spe ctrum of optically thin plasma gives a temperature (characterizing the hardness of the spectrum) of approximately 45 keV. It is noteworthy t hat the shape of the spectrum remains constant for a change in the sou rce luminosity of over an order of magnitude.