The 1994 Large Outburst from 4U0115+63 Observed by BATSE

In 1994 May - June, observations of the recurrent transient Be/X-ray binary 4U0115+63 were carried out with the BATSE experiment on board the Compton Gamma Ray Observatory. Significant hard X-ray detections of the characteristic 3.6 second pulsations were made throughout the duration of the outburst, which lasted for over 40 days. Outbursts from 4U0115+63, a neutron star in a 24.3 day, moderately eccentric orbit, have been observed by many experiments over 20 years. However, this large outburst is the first since 1978 for which the orbital elements may be uniquely determined. We will present the lightcurve of the outburst, a preliminary analysis of the orbital elements, and a comparison of the orbital elements to those determined in other historical outbursts.