  We report on the catastrophic disintegration of P/2016 G1 (PANSTARRS), an
active asteroid, in April 2016. Deep images over three months show that object
is constituted by a central concentration of fragments surrounded by an
elongated coma, and presents previously unreported sharp arc-like and a narrow
linear features. The morphology and evolution of these characteristics
independently point toward a brief event on 2016 March 6. The arc and the
linear feature can be reproduced by large particles on a ring, moving at ~2.5
m/s. The expansion of the ring defines a cone with a ~40deg half-opening. We
propose that G1 was hit by a small object which caused its (partial or total)
disruption, and that the ring corresponds to large fragments ejected during the
final stages of the crater formation.}
