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ATEL # 1956; Elif Beklen (METU), Mark H. Finger (USRA)
on 10 Mar 2009; 1:47 UT
Distributed as an Instant Email Notice (Transients)
Password Certification: Dr. Mark H. Finger (Mark.Finger@msfc.nasa.gov)
Subjects: X-ray, Binaries, Neutron Stars, Pulsars, Transients
Observations with the NaI detectors of the Gamma-ray Burst Monitor (GBM) on Fermi show 66 s pulsations in the 12-25 keV band consistent with the transient Be/X-ray binary pulsar Cepheus X-4 (GS 2138+56). The source was first detected on 2009 March 7 and was again detected on March 8. On both days the pulse frequency was consistent with 15.07552(15) mHz, and the r.m.s. pulsed flux was consistent with 2.8(2)E-10 erg/cm^2/s (12-25 keV).