Dr. Halim Ashkar was awarded the HESS prize for his contribution to the H.E.S.S. multi-messenger program. Halim recently graduated from the Université Paris-Saclay where he worked at IRFU / CEA Paris-Saclay on many aspects of the H.E.S.S. transient program. For example, he added a connection between the UTMOST radio telescope and the H.E.S.S. transients follow-up system, which enables automatic follow-up of FRBs and participated in several MWL campaigns searching for MWL counterparts to FRBs (DeeperWiderFaster, MeerKAT). In this context he was responsible for the joint H.E.S.S. and Swift campaign on SGR1935+2154 during the activity phase in April/May 2020 linked to the detection of the first Galactic FRB and its X-ray counterpart. Halim also developed, implemented and commissioned novel algorithms in the transient follow-up system improving the automatic response of H.E.S.S to gravitational wave detections. These have been used successfully during the physics run O3 of Advanced LIGO and Advanced Virgo. Since 2019 Halim is leading the gravitational wave task group of the H.E.S.S. collaboration. Using this expertise, he also extended the H.E.S.S. gamma-ray burst program to cover large uncertainty regions (e.g. tiling of bursts detected by Fermi-GBM) thereby greatly improving our chances of catching the VHE emission associated to gamma-ray bursts.