  We report the first observations of an astronomical object using a
superconducting tunnel junction (STJ) device, a pixel detector with intrinsic
energy resolution in the optical wavelength range. The Crab pulsar was observed
using a 6 times 6 array of Tantalum STJs at the 4.2-m William Herschel
Telescope on La Palma. Each array element provides photon counting capability
recording up to ~ 10^3 photons per pix per s with an arrival time accuracy of
about 5 microsecond, and providing a wavelength resolution of about 100 nm. We
derive a photometrically resolved light curve which, however, shows no
significant colour index variations with pulsar phase.
