Almost thirty years after its discovery by the COS-B satellite, the gamma-ray source 2CG 078+2, also known as the "gamma-Cygni source", has finally been identified as a gamma-ray loud radio-quiet pulsar, PSR J2021+4026, by the Fermi $\gamma$-ray space telescope, through the direct finding of a 265ms periodicity.

The signal-to-noise ratio of the pulsed $\gamma$-ray data allows to improve the location of the pulsar from 32", as based on the centroid of the $\gamma$-ray photons, to better than 10" deduced from maximizing the strength of pulsations. We have found a Chandra X-ray source positionally consistent with PSR J2021+4026, but with too few counts to permit the confirmation of pulsations in the X-ray data.

Optical imaging of the gamma-Cygni reveals no optical counterpart down to limits of $r^\prime >25.2$ and $i^\prime >23.0$, emphasizing the extreme spectrum of this bright gamma-ray source. The search for an optical counterpart of gamma-Cygni requires the largest telescopes available with the capability of detecting coherent pulsations.