Investigation of the Unusual Outburst Behavior of GRO J2058+42

GRO J2058+42 is a 198 s pulsar discovered by BATSE during a giant outburst in September 1995. The giant outburst was followed by weaker outbursts. The weak outbursts exhibit odd-even intensity behavior from 20-50 keV with a 110 day cycle, which suggests a 110 day orbital period with 2 outbursts per orbit. We propose 2 series of observations spanning about 14 days around the peak of each outburst type to characterize differences in pulse profiles and spectra. These observations and BATSE observations will be used to constrain orbital parameters. Knowledge of the orbital parameters is crucial to the understanding of the unusual outburst behavior of this system.