Energetics of the superflare from SGR1806-20 and a possible associated gravitational wave burst

We discuss in this paper the energetics of large gamma ray superflares observed from Soft-Gamma Repeater sources. The last recorded event has in fact ruled out some models for the energy release. For the first time actual information about a possible associated gravitational wave emission may have been gathered from the LIGO data, even in the case that most of the energy was emitted in gamma-rays. Even upper limits on the amplitude of the latter h at the expected frequency f(c) <= 2 kHz may be useful to further constrain the remaining mechanisms.