The X-ray Light Curve of the Exotic Binary LSI +61(deg) 303

LSI +61(deg) 303 is an exotic, high-mass X-ray binary associated with the highly variable radio source GT 0236+610 and possibly also with the gamma -ray source 2CG135+01. The radio source has a bright (100--300 mJy) radio outburst once per 26.496 day orbital period. In 1996 March we observed LSI +61(deg) 303 with the PCA and HEXTE aboard RXTE as part of a multi-wavelength campaign. Our goal is to understand the relationship between the X-ray and the radio emission from this source. Eleven 10,000-second pointings (one with the PCA off) were distributed over one orbital period with supporting daily radio observations at 2.25 and 8.3 GHz (GBI) and 15 GHz (Ryle telescope). We present the X-ray lightcurve of the source over one orbital period. We compare our data to the radio outburst and the low signal-to-noise average X-ray lightcurve measured with the RXTE ASM (J. M. Parades et al. 1997, A&A 320, L25), as well as ASCA measurements of the X-ray flux and spectrum (D. Leahy, F. A. Harrison, and A. Yoshida 1997, ApJ, 475, 823). We also use the HEXTE data to constrain the hard X-ray spectrum of this source without the possibility of contamination due to the nearby QSO which plagued previous measurements.