SIMBAD references

We observe the nearby, low-density globular cluster M71 (NGC 6838) with the Chandra X-Ray Observatory to study its faint X-ray populations. Five X-ray sources are found inside the cluster core radius, including the known eclipsing binary millisecond pulsar (MSP) PSR J1953+1846A. The X-ray light curve of the source coincident with this MSP shows marginal evidence for periodicity at the binary period of 4.2 hr. Its hard X-ray spectrum and luminosity resemble those of other eclipsing binary MSPs in 47 Tuc, suggesting a similar shock origin of the X-ray emission. A further 24 X-ray sources are found within the half-mass radius, reaching to a limiting luminosity of 1.5x10³⁰ ergs/s (0.3-8 keV). From a radial distribution analysis, we find that 18±6 of these 29 sources are associated with M71, somewhat more than predicted, and that 11±6 are background sources, both Galactic and extragalactic. M71 appears to have more X-ray sources in the range L_X=10³⁰-10³¹ ergs/s than expected by extrapolating from other studied clusters using either mass or collision frequency. We explore the spectra and variability of these sources and describe the results of ground-based optical counterpart searches.