  On 2010 October 13, the X-ray astronomical satellite Rossi XTE, during the
observation of the newly discovered accretion powered X-ray pulsar IGR
J17480--2446, detected a lunar occultation of the source. From knowledge of
lunar topography and Earth, Moon, and spacecraft ephemeris at the epoch of the
event, we determined the source position with an accuracy of 40 mas (1{\sigma}
c.l.), which is interesting, given the very poor imaging capabilities of RXTE
(\sim 1\circ). For the first time, using a non-imaging X-ray observatory, the
position of an X-ray source with a subarcsecond accuracy is derived,
demonstrating the neat capabilities of a technique that can be fruitfully
applied to current and future X-ray missions.
