Pulsar Counterparts of Gamma-Ray Sources

The EGRET catalogue of unidentified X-ray sources has more objects along the galactic disk than at high galactic latitude, where identifications are comparatively easier. On the other hand, the Egret/GRO mission has already identified several known radio pulsars as gamma-ray sources as well as discovering Geminga's nature as a pulsar. If Geminga is not a unique case, as it is very likely not to be, than other galactic sources could, in fact, be radio quiet isolated neutron stars. For these, the identification work is extremely difficult and should anyway start from high resolution X-ray/optical data.Comment: 6 pages, LaTeX, macro aipproc.st

Is the Fuzziness of GRB970228 constant?

In view of the data gathered in September 1997, we review the flux values collected so far for the "fuzziness" seen in the optical counterpart of GRB970228. Comparison between the ground based data collected in March and the data of September 1997 suggests a fading of the fuzz. Given the diversity of the data in hand, the magnitude of the effect and its significance are not easy to quantify. Only new images, both from the ground and with the Space Telescope, directly comparable to the old ones could settle this problem.Comment: 6 pages, Latex, 6 postscript figures, 1 postscript table Proceedings of the 4th Huntsville Gammma-Ray Burst Symposiu

Proposed New Test of Spin Effects in General Relativity

The recent discovery of a double-pulsar PSR J0737-3039A/B provides an opportunity of unequivocally observing, for the first time, spin effects in general relativity. Existing efforts involve detection of the precession of the spinning body itself. However, for a close binary system, spin effects on the orbit may also be discernable. Not only do they add to the advance of the periastron (by an amount which is small compared to the conventional contribution) but they also give rise to a precession of the orbit about the spin direction. The measurement of such an effect would also give information on the moment of inertia of pulsars