We present optical photometry of the eclipsing supersoft source CAL 87. These observations comprise long-term data accumulated as a by-product of the MACHO Project, and high-speed, white-light photometry of a single eclipse. We (i) derive an improved ephemeris of T0 = HJD 245 0111.5144(3) + 0.442 677 14(6)E for the time of minimum light, (ii) find the eclipse structure to be stable over a period of ~4 yr, and (iii) investigate the colour variation as a function of orbital phase. The resolution afforded by the high-speed nature of the white-light observations enables us to see new structure in the light-curve morphology.
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Alcock et al. (1997) studied this question.