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ATEL # 1216; R.H.D. Corbet (UMBC and NASA/GSFC), R.A. Remillard (MIT/MKI), A.M. Levine (MIT/MKI), F.E. Marshall (NASA/GSFC), and T.E. Strohmayer (NASA/GSFC) report for the RXTE ASM team at NASA/GSFC and MIT
on 14 Sep 2007; 21:24 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Robin Corbet (email@example.com)
Subjects: X-ray, Binaries, Neutron Stars, Transients
Observations with the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM) of the soft X-ray transient Aquila X-1 reveal a recent increase in flux that indicates that an outburst is in progress.
Recent daily average measurements with the RXTE ASM in the 2 - 12 keV energy range are: MJD 54351.318008, 0.9 +/- 0.5 cts/s; 54352.5, 3.4 +/- 0.2; 54353.4, 5.2 +/- 0.4; 54354.6, 7.1 +/- 0.4; 54355.3, 8.7 +/- 0.5; 54357.2, 13.1 +/- 0.4. For comparison, the Crab produces 75.5 cts/s in the ASM. The ASM flux from Aql X-1 is now higher than the outburst in May 2007 first detected by Rodriguez et al. (ATEL #1079) and higher than any daily average flux seen with the ASM since at least MJD 53720 (December 2005).