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Rapid Brightening of A0535+26 Observed by Fermi GBM

ATEL # 2324; Colleen A. Wilson-Hodge (NASA/MSFC), Mark H. Finger (USRA), Ascension Camero-Arranz (FECYT) and Valerie Connaughton the GBM Occultation Project and GBM Pulsar Project teams
on 2 Dec 2009; 23:54 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Dr. Mark H. Finger (

Subjects: X-ray, Gamma Ray, Binaries, Pulsars, Transients
Referred to by ATEL #: 2336, 2337

A0535+262 is brightening rapidly in GBM observations. On November 30, 2009, Fermi GBM Earth occultation observations showed that the flux had risen rapidly to 480+/-100, 460+/-70, and 620+/-100 mCrab in the 8-12, 12-25, and 25-50 keV bands. On December 1, 2009 the flux continued to rise to 580+/-105, 640+/-50, 444+/-80 mCrab in the 8-12,12-25, and 25-50 keV bands respectively.

After remaining fairly constant at 10 mCrab from November 19-24, the pulsed rms flux in the 12-50 keV band began to rise, reaching 70 mCrab on December 1. From Nov 29 to Dec 1 the pulse frequency increased at a rate of 1.22(7) x 10E-12 Hz/s reaching 9.66094(4) mHz on Dec 1.5.

Observations with other observatories are encouraged.

GBM Occultation Project and GBM Pulsar Project

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R. E. Rutledge , Editor
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