Infrared Photometric Variability of GX 13+1 and GX 17+2

Bandyopadhyay, Reba M.; Charles, Philip A.; Shahbaz, Tariq; Wagner, R. Mark
Bibliographical reference

The Astrophysical Journal, Volume 570, Issue 2, pp. 793-798.

Advertised on:
5
2002
Number of authors
4
IAC number of authors
1
Citations
14
Refereed citations
14
Description
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.