SIMBAD references

C. B. Markwardt, University of Maryland and Goddard Space Flight Center; J. M. Miller, Harvard-Smithsonian Center for Astrophysics; and R. Wijnands, University of St. Andrews, report a new outburst of the millisecond accreting pulsar SAX J1808.4-3658 (cf. IAUC 7369). In RXTE PCA scans of the Galactic center on Oct. 13.279 UT, an x-ray source whose position is consistent with SAX J1808.4-3658 was detected with a flux of 65 mCrab (2-10 keV). On Oct. 9.5, the PCA flux was < 0.5 mCrab. Two minutes of pointed data detected x-ray pulsations at the frequency 400.953 ± 0.008 Hz (barycentered). This frequency is consistent with the known pulsar spin frequency and orbital Doppler modulation. The RXTE ASM instrument detected the source on Oct. 14.30 and 14.37 at fluxes of 105 and 76 mCrab, respectively. In its 1998 outburst, the source also exhibited fast radio and optical transients, so multiwavelength observing is encouraged.