CCD photometry of low mass X-ray binaries: LMCX-2, 1556-60 and 1957+11

We present preliminary results from V-band CCD photometric observations of several low-mass X-ray binaries with faint optical counterparts obtained at ESO and CFHT from February to September 1984. LMCX-2 exhibits large (0.3–0.5 magnitude) variations consistent with a possible 6.4 hour period. 1556-605 shows 0.2–0.5 magnitude variations suggesting that the orbital period is longer than 7 hours. 1957+115 shows short time scale (1 hour) variations of 0.1 magnitude.Based on observations obtained at the European Southern Observatory, La Silla, Chile and with the Canada-France-Hawaii telescope, Mauna Kea, HI.