The Spectrum and Accurate Location of GRS 1758 - 258

We observed the “micro-quasar” GRS 1758–258 four times with Chandra. Two HRC-I observations were made in 2000 SeptemberOctober spanning an intermediate-to-hard spectral transition (identified with RXTE ). Another HRC-I and an ACIS/HETGS observation were made in 2001 March following a hard-to-soft transition to a very low flux state. The accurate position (J2000) of the X-ray source is RA = 18 01 12.40, Dec = −25 44 36.0 (90% confidence radius = 0.6), consistent with the purported variable radio counterpart. All images are consistent with GRS 1758–258 being a point source, indicating that any bright jet is less than ∼1 light-month in projected length, assuming a distance of 8.5 kpc. The March spectrum is well-fit with a multi-color disk-blackbody with an inner temperature of 0.50 ± 0.01 keV, interstellar absorption of nH = (1.59± 0.05)× 10 22 cm, and (un-absorbed) 1−10 keV luminosity of 4.5×10(D/8.5 kpc) ergs s. No narrow emission lines are apparent in the spectrum and upper limits to line equivalent widths are given.