TITLE: GCN CIRCULAR NUMBER: 29650 SUBJECT: GRB 210312B: A long GRB detected by INTEGRAL DATE: 21/03/12 22:02:02 GMT FROM: Sandro Mereghetti at IASF-Milano/INAF S.Mereghetti (INAF, IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC, Versoix) and J.Borkowski (CAMK, Torun) report: a gamma ray burst lasting about 5 s has been detected by IBAS in the IBIS/ISGRI data at 20:52:17 UT of March 12, 2021 The refined coordinates (J2000) are: R.A.= 155.8431 deg DEC.= +76.8714 deg with an uncertainty of 2 arcmin (90% c.l.). The burst had a peak flux of about 1.5 ph/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 2e-7 erg/cm2 A plot of the light curve will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html