Thermonuclear bursts from the candidate ultracompact binary 1A 1246-588
Some activity recently from an old Ariel V source, 1A 1246-588. It's listed in SIMBAD as a high-mass binary, but recent optical observations instead suggest that it is an ultracompact binary with a very low-mass donor. Then, in late May, the RXTE/ASM detected a flare, which subsequent analysis showed to be consistent with a long thermonuclear burst. (An earlier burst was detected by BeppoSAX). These types of bursts occur in very low-accretion rate sources where a deep fuel layer can build up prior to ignition. There are only a handful of ultracompact binaries in the Galaxy, and substantial interest in their properties and evolution.
See also ATel 875