X-Ray Flare in Lupus

L. Kaluzienski and S. Holt, Goddard Space Flight Center, report the detection with the Ariel 5 all-sky monitor of an x-ray flare from a source in the constellation Lupus. The source appeared during Oct. 25d09h-25d14h UT, attained a peak 3-6-keV intensity of ~ 0.33 Crab on Oct. 26 and faded back below detectable levels early on the 27th. Upper limits to the flux during ~ 0.5-day periods adjacent to the flare are ~ 0.1 Crab. Fine-mode observations of this region conducted on Oct. 19-20 and 28 yield corresponding upper limits of ~ 0.05 Crab. The source is located at R.A. = 15h13m, Decl. = -43o.2 (equinox 1950.0), with a 90-percent-confidence error-circle radius of ~ 2o. It is noted that the observed flare timescale is intermediate between those of previously reported x-ray flares (cf. IAUC 3174) and the x-ray novae and that no known x-ray sources lie within the error Circle.