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ATEL # 2023; Mark H. Finger (USRA), Elif Beklen (METU)
on 18 Apr 2009; 1:45 UT
Password Certification: Dr. Mark H. Finger (Mark.Finger@msfc.nasa.gov)
Subjects: Binaries, Pulsars, Transients
Pulsations from the recently discovered accreting pulsar Swift J0513.4-6547 in the LMC (H. A. Krim et al. ATEL #2011) have been detected in the Fermi/GBM rates between 2009 March 1 and March 28. Pulse searches were made for several multi-day intervals covering January 30 to April 15. The searches included both trial frequencies near the 36.66 mHz (27.28 s period) RXTE measurement (ATEL #2011), and trial frequency rates in the range expected for accreting pulsars near Eddington luminosity. The intervals with detections were:
Time Range Epoch Frequency Frequency Rate (MJD) (MJD) (mHz) (1E-12 Hz/s) 54819.0-54897.0 54893.984 36.59407(13) 48(2) 54897.0-54902.0 54899.339 36.62742(18) 102(5) 54904.6-54908.5 54906.509 36.67029(15) 30(3) 54908.5-54912.5 54910.552 36.67429(13) -8(3) 54912.5-54918.0 54915.296 36.66989(13) -6(3)These times, frequencies, and frequency rates are barycentric. A plot may be seen at http://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/swiftj0513_fig1.png The pulsed flux (mean-minimum 12-25 keV) reached 15 mCrab between March 18 and March 22, giving a lower limit to the luminosity of 7E+37 erg/cm^2 s. The frequency rate in the second detection interval is consistent with a pulsar accreting from a disk near the Eddington rate. The negative frequency rates in the last two intervals are likely due to Doppler shifts from the (unknown) binary orbit.
GBM Pulsar Project