F. Haberl et al., ROSAT OBSERVATIONS OF THE LMC BE X-RAY BINARY EXO-0531.1-6609 - THE LONG-TERM VARIABILITY/, Astronomy and astrophysics, 302(1), 1995, pp. 1-4
The Be/X-ray binary EXO 0531.1-6609 was in the field of view of 40 poi
nted ROSAT PSPC observations distributed over 4 years. Most of the obs
ervations yielded upper limits below 0.02 counts s(-1) consistent with
several detections at this low-intensity level. A strong outburst las
ting for more than two months was seen from March to May 1993. With a
maximum observed intensity of 0.5 counts s(-1) the brightness of the o
utburst is comparable to that seen in 1983 by EXOSAT. The PSPC energy
spectrum is consistent with a power law with photon index 1.5 as typic
ally observed from this class of X-ray binaries.