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TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2306 SUBJECT: RXTE PCA Observations of SGR1806-20 Region DATE: 03/07/18 02:53:20 GMT FROM: Craig Markwardt at GSFC <craigm@milkyway.gsfc.nasa.gov> RXTE PCA Observations of SGR 1806-20 Region A. Ibrahim (GWU/GSFC), C. Markwardt (UMD/GSFC), J. Swank (GSFC), K. Hurley (UCB), T. Cline (GSFC), & W. Parke (GWU) Report: In response to the burst activity reported by IPN on Jul 14 (GCN 2297), we pointed the RXTE PCA at the position of SGR 1806-20 on Jul 15, 11:35-12:20 UT. A 0.4 mCrab pulsed flux was detected with a period of 5.54 s +/- 0.01 s. The PCA saw 3.5 mCrab total flux, but as much as half is due to Galactic ridge emission in the field of view, so that the pulsed fraction could exceed 20%. The large difference between the pulse period and the last observed pulse period of SGR 1806-20 (Woods et al. 2002, ApJ, 576, 381) suggests that a new pulsar is present. There are no known pulsars with that period in the 1.2 deg radius field of view of the PCA and we can rule out the nearby candidate SGR 1801-23 (Cline et al. 2000, ApJ, 531, 407). If the new pulsar were responsible for the recent bursts, there would be three SGRs in a small region. However it is possible that both SGR 1806-20 and another pulsar are active simultaneously. PCA scanning observations are planned. This message is citeable.
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