A0538-66

N. E. White and P. J. N. Davison, Mullard Space Science Laboratory; and G. Carpenter, Birmingham University, report: "Ariel 5 observations of the Large Magellanic Cloud revealed two x-ray outbursts, on June 30 and July 16, respectively. The risetime of these events was one to two hours, and there followed an exponential-like fall with an e-folding time of eight hours. The peak luminosity was about one-sixth that of the Crab (5 x 10**-9 erg cm**-2 s**-1 in the 2-17 keV band), and there was some evidence from the second outburst for a regular pulsation at about 80 seconds. The data are consistent with both events arising from the same source. The rmc experiment yields a 90-percent-confidence position of R.A. = 5h39m +/- 4m, Decl. = -66o.9 +/- 0o.2 for the earlier event. This measurement was made while the satellite pointing axis was drifting rapidly. Consequently an indirect method was required to obtain the position, and this is reflected in the large uncertainties. We note that the above position is only 0o.4 from that of LMC X-4 and that the July 16 outburst occurred during an LMC X-4 eclipse (cf. IAUC 3095)."