We report the results of Hubble Space Telescope ( HST ) and Chandra X-ray Observatory ( CXO ) observations of the GLIMPSE-C01 ( hereafter GC01 ) star cluster .
Color-magnitude and color-color diagrams suggest a cluster age of \gtrsim 2 Gyrs up to \sim 10 Gyrs ( dependent on GC01 ’ s metallicity ) , a distance of 3.3-3.5 kpc , and strong differential reddening with A _ { V } = 14 - 22 .
After performing astrometric corrections , we find that nine of the 15 X-ray sources have at least one NIR counterpart within the 2 \sigma CXO positional error circles .
However , given the very high density of NIR sources in the cluster , most of these counterparts are likely due to chance coincidence .
We jointly analyze the X-ray and NIR properties to assess the likelihood of true associations .
Based primarily on their X-ray properties , we identify an LMXB candidate ( source X2 ) , a CV candidate ( source X1 ) , and an AB candidate ( source X9 ) .
Source X11 is detected during an X-ray flaring episode with a flare luminosity ( L _ { X } = 2.1 \times 10 ^ { 33 } erg s ^ { -1 } ) and has a quiescent luminosity L _ { X } < 8.0 \times 10 ^ { 30 } erg s ^ { -1 } , in 0.5–8 keV at the distance of GC01 , suggesting that the source is either an AB or CV .
We also discuss the limits on an intermediate mass black hole at the center of GC01 and the challenges of X-ray source classification imposed by the limitations of the existing data and instrumentation along with future prospects in the James Webb Space Telescope era .