  The intense galactic X-ray source GX 349+2 (Sco X-2) belongs to the class of
persistently bright low-mass X-ray binaries called Z-sources. GX 349+2,
although observed in X-rays for more than 30 years, has only recently been
optically identified with a 19th mag star. Of the six known Z-sources, only two
(Sco X-1 and Cyg X-2) have been studied in the optical. It has been suggested
that Z-sources as a group are characterized by evolved companions and
correspondingly long orbital periods (Sco X-1, P=0.8 d; Cyg X-2, P=9.8 d).
Recently Southwell et al. (1996) have presented spectroscopic observations of
GX 349+2 suggesting a 14 d orbital period. We have obtained broadband
photometry of the system on six consecutive nights, and find a statistically
significant 21.85 +/- 0.4 h (3 sigma) period of 0.14 mag half-amplitude,
superposed on erratic flickering typical of Sco X-1 type objects. As with other
Z-sources, caution will be needed to insure that the variations are truly
periodic, and not simply due to chaotic variability observed over a relatively
short time span. Depending on the origin of the brightness variations, our
proposed period could be either the orbital or half the orbital period. If our
period is confirmed, then the nature of the 14 d spectroscopic variation found
by Southwell et al. (1996) is unclear. There is evidence that the mass function
of GX 349+2 is similar to that of Sco X-1.
