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We present the results of an H-alpha monitoring campaign on the BeXRB andmicroquasar system LS I +61 303. We use radial velocity measurements of HeIlines in our spectra to re-evaluate the orbital elements and to betterestablish the time of periastron. We list equivalent widths and otherparameters for the H-alpha emission line and discuss the orbital phase relatedvariations observed. We call attention to a dramatic episode of emissionweakening that occurred in less than a day that probably resulted from exposureto a transient source of ionizing radiation. We argue that the increase inH-alpha and X-ray emission following periastron probably results from thecreation of an extended density wave in the disk created by tidal forces. Wealso discuss estimates of the size of the disk from the H-alpha equivalentwidth measurements, and we suggest that the disk radius from the averageequivalent width corresponds to a resonant truncation radius of the disk whilethe maximum equivalent width corresponds to a radius limited by the separationof the stars at periastron. We note that a nearby faint companion is probablyan unrelated foreground object.Comment: 18 pages including 7 figures and 2 tables, accepted to Ap

Joint Hα and X‐Ray Observations of Massive X‐Ray Binaries. II. The Be X‐Ray Binary and Microquasar LS I +61 303