TITLE: GCN CIRCULAR NUMBER: 20086 SUBJECT: GRB 161020A: A long GRB detected by INTEGRAL DATE: 16/10/20 20:35:50 GMT FROM: Sandro Mereghetti at IASF-Milano/INAF S.Mereghetti (IASF-Milano), V. Savchenko (APC, Paris), D.Gotz (CEA, Saclay), C.Ferrigno (ISDC, Versoix), and J.Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report: a gamma ray burst lasting about 15 s has been detected by IBAS in the IBIS/ISGRI data at 00:34:40 UT of 2016 October 20. This burst was also detected by Fermi/GBM (trigger num. 498616490). The burst occurred immediately after the end of a slew of the INTEGRAL satellite. For this reason the corresponding IBAS Alert was not distributed in real time. From an offline analysis we derived the burst coordinates (J2000): R.A.= 161.0309 deg DEC.= -54.7687 deg with an uncertainty of about 2 arcmin (90% c.l.). The burst had a peak flux of 0.8 counts/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 4e-7 erg/cmq. A plot of the light curve will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html