2002ApJ...570..793B

We present infrared photometry of the Galactic bulge X-ray binary systems GX 13+1 and GX 17+2 obtained in 1997 July and August using OSIRIS on the 1.8 m Perkins Telescope at Lowell Observatory. GX 13+1 clearly varies over ∼0.6 mag in the K band. Our light curve suggests a modulation on a timescale of ∼20 days, which is in agreement with previously proposed orbital periods for the system. The IR counterpart of GX 17+2 is also variable in the K band over ∼0.8 mag on a timescale of days to weeks, extending the variability first seen by Naylor, Charles, & Longmore). We discuss the implications our data have for Deutsch et al.'s identification of ``star A'' as the true IR counterpart of GX 17+2. The variability observed in our photometry of the blend of star A and the foreground star NP Ser implies a ∼4 mag intrinsic variation in the K band for GX 17+2.