New mode of activity of MXB 1730-335.

The results of an observation of a new mode of activity in the X-ray source MXB 1730-335 are reported. The observation was conducted with the X-ray astronomy satellite Hakucho during August 1979. Changes in the shape and energy content of the bursts are described for three phases of activity. Particular attention is given to a description of the bursts during the second phase of activity. The peak luminosity of bursts during the second phase was between 1 and 3 x 10 to the 38th ergs/s, decreasing as the duration increased beyond 150 s. The total energy E was in the range 1-6 x 10 to the 40th erg, corresponding to an accreted mass of 1-5 x 10 to the 20th g. The energy spectrum is simulated by a blackbody spectrum of temperatures from 1.5 to 2.0 keV, with a column density for the absorbing matter of 2.4 x 10 to the 22nd H per sq cm. The area of the emitting region was about 10 to the 13th sq cm.