1996A&A...314L..21G

We have observed GRS 1739-278 with the ROSAT HRI on March 31, 1996. The improved X-ray position proves the identification with an earlier discovered variable radio source. We derive an extinction of A_V=14±2 from the dust scattering halo, which implies a distance of d∼6-8.5kpc. Thus, GRS 1739-278 radiates at least near the Eddington limit for a 1M_☉ compact object. The existence of the dust scattering halo necessitates a prolonged X-ray activity period prior to the ROSAT observation. Combined with the non-detection by Granat during an earlier galactic center observation, we speculate that the X-ray turn-on of GRS 1739-278 happened in Nov./Dec. 1995.