0770002

AGILE detected 3C 454.3 at an extremely high gamma-rayflux level about 1.8E-5 ph/cm2/s on December 3rd asreported in ATel #2326. Subsequently Fermi detected it evenat higher flux about 2.2E-5 ph/cm2/s as reported inATel #2328.3C 454.3 is currently the most intense gamma-ray sourcein the sky much brighter than the Vela pulsar.The response time we request is dictated by the exceptionalityof this event since this is currently the most intense gamma-rayflare form an AGN ever detected.The source is very active also in the optical R band as reportedin ATel #2325 reaching a magnitude of R=14.1.The observations should be performed with the hexagonal ditherpattern in order to obtain a simultaneous coverage below 20 keVwith the JEM-X instrument during the whole observation.We request possibly a single observation 400 ksec longwith no follow-up observations.During a gamma-ray flare in November 2007 we obtainedan INTEGRAL ToO and we published the results inVercellone et al. 2009 ApJ 690 1018. [truncated! Please see actual data for full text]