Timing the Geminga Pulsar with EGRET Data

摘要

The pulsation of Geminga has been detected to date only at high energies (Egreater than 0.1 keV). Since x-ray exposures are short and Geminga is at best only marginally detected in gamma-rays at E less than 30 MeV, the primary means of timing Geminga is with high-energy gamma-rays. The EGRET observation data are analyzed to determine the 1995 ephemeris for Geminga which is provided in this report. We continue to count every revolution of Geminga during the GRO mission with a rotational phase resolution which improves with additional exposure. With improved statistics, two additional peaks are tentatively detected in the 'minor bridge' region.