BeppoSAX Observations of the Soft Gamma-Ray Repeater SGR 1806-20

We have observed with the BeppoSAX satellite the quiescent counterpart of the Soft Gamma-ray Repeater SGR 1806-20. Observations performed in October 1998 and in March 1999 showed that this pulsar continued its long term spin-down trend at an average rate of ~8 10e-11 s/s while its flux and spectrum remained remarkably constant between the two observations, despite the soft gamma-ray bursting activity that occurred in this period. We also reanalyzed archival ASCA data, that when compared with the new BeppoSAX observations, show evidence for a long term variation in luminosity.