Probing Vela Pulsar down to 20 GeV with HESSII observations

Observations of the Vela pulsar (PSR B0833-45) with the High Energy Stereoscopic System phase II array (H.E.S.S.II) have resulted in a high-significance detection of its pulsed emission down to 20 GeV. The very low-energy threshold reconstruction and analysis methods developed specifically for the monoscopic mode are presented together with detailed comparison of the results obtained with five years of Fermi-LAT data. A very good agreement is obtained between the two instruments, thereby validating the overall analysis chain and the response model of the largest H.E.S.S. telescope (CT5). The high event statistics are used to probe the spectrum of PSR B0833-45 above 20 GeV. (authors)