The Hubble Deep Field North reveals a supernova at z~0.95

We report the discovery of a variable object in the Hubble Deep Field North (HDF-N) which brightened, during the 8.5 d sampled by the data, by more than 0.9 mag in I814 and about 0.7 mag in V606, remaining stable in B450. Subsequent observations of the HDF-N show that two years later this object has dimmed to about its original brightness in I814. The colours of this object, its brightness, its time behaviour in the various filters and the evolution of its morphology are consistent with it being a Type Ib supernova in a faint galaxy at z.