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4U 1901+03 observations with Fermi/GBM

ATel #3839; Peter Jenke (MSFC/NPP), Mark H. Finger (USRA)
on 30 Dec 2011; 22:25 UT
Credential Certification: Dr. Mark H. Finger (Mark.Finger@msfc.nasa.gov)

Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar

Referred to by ATel #: 12515

Pulsations from the HMXB 4U 1901+3 are currently being detected with Fermi/GBM in the 8-25 keV band with a period near 2.762 s. The current outburst was previously reported by Sootome et al. (ATel #3829). We first detected this source on December 20. Observations from December 20 - 29 are inconsistent with the orbital ephemeris given by Galloway et al. (2005) unless a correction is made to the orbital epoch. We have calculated a new orbital epoch: T_pi/2 = MJD 55927.25(30). From this epoch and that given by Galloway et al. we calculate a refined orbital period of 22.5348(21) days. Using this new ephemeris we measure a spin frequency of 362.0838(27) mHz for the time period between December 23.0 and December 25.0.

GBM Pulsar Project