2002ApJ...577L..19R

We report on a deep search for radio pulsations toward five unidentified ASCA X-ray sources coincident with EGRET γ-ray sources. This search has led to the discovery of a young and energetic pulsar using data obtained with the new Wideband Arecibo Pulsar Processor. PSR J2021+3651 is likely associated with the X-ray source AX J2021.1+3651, which in turn is likely associated with the COS B high-energy γ-ray source 2CG 075+00, also known as GeV J2020+3658 or 3EG J2021+3716. PSR J2021+3651 has a rotation period of P∼104 ms and P{dot}∼9.6x10^–14, implying a characteristic age of τ_c∼17 kyr and a spin-down luminosity of E{dot}∼3.4x10³⁶ ergs.s^–1. The dispersion measure DM∼371 pc.cm^–3 is by far the highest of any observed pulsar in the Galactic longitude range 55°<l<80°. This DM suggests a distance d≳10 kpc and a high γ-ray efficiency of ∼15%, but the true distance may be closer if there is a significant contribution to the DM from excess gas in the Cygnus region. The implied luminosity of the associated X-ray source suggests the X-ray emission is dominated by a pulsar wind nebula unresolved by ASCA.