1 National Space Institute, Technical University of Denmark2 Astrophysics, National Space Institute, Technical University of Denmark3 unknown
During an observation of the Galactic Center the JEM-X instrument on INTEGRAL detected an unusally long X-ray burst from GX 3+1. The burst began on August 31 at 18:57 UTC After an precursor spike lasting 7 s where the burst reached a flux of about 2000 mCrab in the 4 to 20 keV band the flux fell to around 500 mCrab and then decayed with an e-folding time of about 700 s. This burst appear as intermediate between the normal type-I X-ray bursts (e-folding times up to a few tens of seconds) and the very long "superbursts" (e-folding times of several hours). Prior to the outburst the source flux was about 150 mCrab. Follow-up observations are encouraged.