The intense galactic X-ray source GX 349+2 belongs to the class of persistently bright low mass X-ray binaries called Z-sources. 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). GX 349+2 has only recently been optically identified with a 19th magnitude star. We previously reported on photometric evidence for a 22 h period. Additional observations obtained on 6 consecutive nights in July 1996 confirm this period and refine its value to 22.4 h. X1608-52 is one of only a few recurrent soft X-ray transients which exhibit persistent X-ray emission between outbursts. Observations of the field after the recent X-ray outburst (IAUC 6331, 6336) show that the faint optical counterpart QX Nor last seen in 1977 has reappeared. Data from May-July 1996, 3-5 months after the outburst, show the counterpart at about R=19.9 and variable on timescales of days. A comparison to identical observations last year shows that the object has brightened by at least 2 mag in R. We also detected QX Nor in the IR in BOTH quiescence and outburst. A faint source is visible at J but not R in May 1995. J frames obtained in August 1996 show the star brighter by about 0.8 mag (J~ 17). GX 13+1 is a bright X-ray burst source, located in the galactic bulge. Due to the heavy obscuration in the galactic center direction, no optical counterpart brighter than R ~ 22 mag has been detected, although recently a K=12 IR counterpart was found. Our previous photometry suggests variability of ~ 0.4 mag on a timescale of several days. Results of a recent photometric monitoring program will be presented.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1996