The X-ray source RX~J004717.4-251811 in the nearby starburst galaxy NGC~253 was found to undergo changes from a low to a high state twice , during an XMM-Newton EPIC observation in December 2000 and also during a Chandra observation one year earlier .
These transitions are interpreted as egresses from eclipses of a compact object in a high mass X-ray binary system ( HMXB ) .
The phase of eclipse egress during the Chandra observation is given by barycenter corrected MJD 51539.276 \pm 0.006 and the binary period determined to p = ( 352.870 \pm 0.012 ) d / n by the time difference between the two egresses and number n of periods in-between .
Allowed periods may be further constrained by additional XMM-Newton , Chandra , ROSAT , and Einstein observations resulting in only seven acceptable periods with 1.47024 d and 3.20793 d most promising .
No significant regular pulsations of the source in the range 0.3–1000 s were found .
Fluctuations on time scales of 1000 s were observed together with extended intervals of low intensity .
The energy spectrum during the bright state can best be described by an absorbed flat power law ( N _ { H } =1.9 \times 10 ^ { 21 } cm ^ { -2 } , \Gamma =1.7 ) .
In the bright state the source luminosity is 4 \times 10 ^ { 38 } erg s ^ { -1 } ( 0.5–5 keV ) , just compatible with the Eddington luminosity of a 1.4 M _ { \sun } neutron star .
A possible optical identification is suggested . RX~J004717.4-251811 parameters are compared to other eclipsing X-ray binaries ( XRBs ) .