The discovery of proper motion of Geminga's optical counterpart

Summary After reviewing the evidence that the X/γ-ray source 1E0630+ 178/Geminga is a relatively young, isolated neutron star similar to the Vela Pulsar, we present our recent discovery of the proper motion of its faint optical counterpart. This measurement confirms the proposed optical identification, and suggests a distance of the order of 100 pc, consistent with the upper limits derived from the Geminga high-energy emission. The hypothetical nearby supernova event which originated Geminga about 350 000 years ago is also briefly discussed. Paper presented at the 6th Cosmic Physics National Conference, Palermo, 3–7 November 1992.