The Fermi satellite was launched in 2008 with two gamma-ray sky observation instruments on board. The LAT (Large Area Telescope) has detected more than 250 gamma-ray emitting pulsars in the energy range between 20 MeV and 300 GeV. These discoveries were largely possible thanks to the contribution of radio observations carried out at the NRT in Nançay. Thanks to regular monitoring and to precise ephemerides, these observations have allowed to stack the rare gamma-ray photons in phase with the rotation of the pulsars. The comparison of the radio and gamma-ray emission beams has also brought new answers about the emission mechanisms at work in the magnetospheres of neutron stars.
Lucas Guillemot coordinates the gamma-ray pulsar timing observations with Fermi and the NRT and ensures the availability of the data to the national and international community. This activity constitutes an Observation Service of the Institut National de Sciences de l’Univers du CNRS (INSU).