GX 339-4

M. Oda and the Hakucho Team, Institute of Space and Astronautical Science, University of Tokyo, telex: "The Hakucho satellite has been observing GX 339-4 (= 4U 1659-48) since June 5 (cf. IAUC 3609). The source exhibited intermediate intensity (0.1-0.2 Crab at 1-10 keV) during June 5-22, with a moderate day-by-day intensity variation. Beginning about June 24, GX 339-4 turned into an unusually bright state (0.4-0.5 Crab at 1-10 keV). During a scan of the data, no significant intensity variability has been found on timescales of 0.1-500 s (upper limit 10-20 percent). A more detailed analysis is in progress. Hakucho will have continued observing this object until about July 20. We encourage optical observers to monitor this source.