Observation of an outburst of comet Hale-Bopp in September 1996

The light curve and images of comet Hale-Bopp (C/1995 OI) in September 1996 are studied. It is found that an outburst happened on 10-11 September 1996 . The magnitude of the inner coma region increased by 2.1 and 1.4 mag on th ese two days, respectively. Two globular ejecta were found near the nucleus of the comet on 10-11 September 1996. By extrapolating backward from the e jecta, it is found that the initial time of the outburst was on 9 September 1996 (9.5 +/- 0.2 UT). The physical reason for this outburst is still unce rtain. The projected radial velocities of ejecta are 120 and 97 m/s. (C) 20 00 Elsevier Science Ltd. All rights reserved.