Today, June 04, 2021, the H.E.S.S. collaboration published results of observations of the gamma ray burst GRB190829A. The study appeared in Science Vol. 372, Issue 6546, pp. 1081-1085 (2021) and is available on arXiv 2106.02510 as well. Only the third gamma ray burst to have been detected at very high energies (photon energy > 100 GeV), GRB190829A has a very small distance to Earth compared to most GRBs observed in all energy bands. With a redshift of only z=0.0785, the gamma rays emitted from this explosion suffer only little absorption on their way to Earth and its properties can hence be explored even up to TeV energies, significantly exceeding the range offered by the first two GRBs detected in this energy band.
Unlike GRB180720B, detected with the H.E.S.S. telescopes in 2018 and GRB190114C, observed with the MAGIC telescopes earlier in 2019, GRB190829A has been monitored during three subsequent nights. This extended coverage of the decay in flux, together with high-quality spectral studies offered new insights into the physical processes in these most luminous cosmic explosions. Further information may be obtained in the June 2021 edition of the ‘HESS – Source of the Month’.