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The large H.E.S.S. II Cherenkov telescope in Namibia at dusk

Recurrent nova · August 2021

RS Ophiuchi

The 2021 eruption of the recurrent nova RS Ophiuchi became the first Galactic transient detected at very high energies.

Our part

Observed and announced within the H.E.S.S. transients programme.

Follow-up, step by step

  1. August 2021
    Optical observers

    The nova erupts, visible to the naked eye.

  2. Shortly after
    Fermi-LAT

    Detects the outburst in gamma rays.

  3. 9 August 2021
    H.E.S.S.

    First night of observations gives a clear detection, reported promptly to the community.

  4. First five nights
    H.E.S.S.

    A strong signal at the position of the nova.

  5. About 17 days later
    H.E.S.S.

    The emission has faded but is still detectable.

Artist's impression of the RS Ophiuchi binary system, a white dwarf accreting matter from a red giant companion

Papers

From the news

The story as it happened.