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Welcome to the webpages of H.E.S.S., one of the leading observatories studying very high energy (VHE) gamma-ray astrophysics. To learn more about H.E.S.S. and the high energy universe, or to view pictures from the telescopes and the site in Namibia visit the About H.E.S.S. section.

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H.E.S.S. operations extended until 2024
October 1, 2021

Major step for the HESS experiment and ground-based gamma-ray astronomy in general: In the current context of emerging multi-messenger, multi-wavelength astronomy, the HESS Steering Committee evaluated the possible options for the future of HESS beyond the currently ongoing first extension phase. After careful analysis of the proposed strategy for the upcoming years, the Steering Committee unanimously voted in favour of a second extension phase of HESS operations for an additional duration of 2 years, ending October 1, 2024. The corresponding extension agreement is currently being finalized between the relevant parties.

The second extension was approved in recognition of the very succeful measures to increase the operational efficiency, further increase of the amount of observing hours by including moonlight observations, significant progress in data analysis, important scientific results emerging from operations in recent years and an attractive science program for the forthcoming three-years. This way, HESS will be preparing for the future CTA era while continuing to deliver exciting and excellent science.

H.E.S.S. collaboration member Alison Mitchell wins Emmy Noether grant
August 14, 2021

Congratulations to Alison Mitchell for winning an Emmy Noether grant from the Deutsche Forschungsgemeinschaft. Her six-year project "Unveiling the Origin of Galactic Cosmic Rays: Exploring Pulsar Environments at the Highest Energies" will use H.E.S.S. and ultimately CTA to tackle this important question in two steps: After focusing on technical improvements to data analysis and towards detailed and precision studies of individual PWNe systems, the second aim will be to increase the number of known TeV PWNe and halos, conducting multi- wavelength and population studies. The grant will enable Alison to start an Emmy Noether team within the H.E.S.S. group of Erlangen University in October 2021.

The project focus is on the acceleration and transport of Cosmic Rays in Pulsar environments. Within the last year, evidence has emerged that Pulsar Wind Nebulae (PWNe) accelerate electrons and positrons to PeV energies, but the origin of other PeV particles remains unconfirmed. Recent measurements of two nearby pulsars showed surprisingly slow diffusion of Cosmic Rays, causing some tension with current theoretical models.

Alison has started her scientific career as a PhD student in the H.E.S.S. group at MPIK in Heidelberg and subsequently worked for the CTAO, the University of Zurich and ETH. During this time Alison remained a member or an associate member, respectively, of the H.E.S.S. collaboration. For her numerous contributions within the H.E.S.S. collaboration, Alison was awarded the H.E.S.S. Prize in 2020.

New insights into gamma ray burst: H.E.S.S. publishes observations of the third GRB detected at very high photon energies
June 04, 2021

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'

Gammapy selected as open-source software of choice for analysis of H.E.S.S. data
May 10, 2021

Data obtained with the H.E.S.S. telescopes are recorded and stored in "root" format, which is widely used in the particle physics community. From the early phases the collaboration developed several proprietary analysis methods. Processed data are stored in proprietary file structures. In order to facilitate exchange and common treatment of data obtained with other facilities and to allow efficient adaptation of open-source software, the H.E.S.S. collaboration explored data analysis with different open-source tools using the open FITS data format for some time.


Based on extensive tests and development and adaptation, the collaboration now chose Gammapy as its open-source analysis framework. Gammapy v1.0rc Gammapy will be released in the next weeks.

Gammapy-based studies will complement the well-established proprietary analysis methods used by the H.E.S.S. collaboration and facilitate further development of the tools by challenges posed in exploring real observations obtained with H.E.S.S..

H.E.S.S. collaboration member Manuel Meyer wins ERC grant
April 10, 2021

Congratulations to Manuel Meyer for winning a Starting Grant from the European Research Commission on "Searching for axion and axion-like-particle dark matter in the laboratory and with high-energy astrophysical observations". Manuel and his group will join the H.E.S.S. group at the University of Hamburg starting June 2021.

The grant will enable Manuel to start a dedicated research group which will search for hypothetical axions and axion-like particles. Such particles are predicted in certain theories of particle physics and could explain several unresolved questions in particle physics and cosmology. For example, they are candidates to explain the mysterious dark matter. Manuel Meyer’s team will search for axions by contributing to dedicated laboratory experiments and by searching for their signatures with astrophysical observations — including observations of distant galaxies with the H.E.S.S.

Manuel has started his scientific career as a PhD student in the H.E.S.S. collaboration, has worked as a H.E.S.S. member in several groups of the collaboration thererafter and kept his association with the H.E.S.S. collaboration also while working as a Feodor Lynen Research Fellow at Stanford University.

H.E.S.S. completes a very successful year 2020
February 10, 2021

2020 will have its place in history. The Covid-19 pandemic affected the lives of many people all over the world. That is why we are grateful to the continued efforts of our local crew and shifters, and many members of the collaboration, in keeping H.E.S.S. running during this unprecedented time. Thanks to their hard work, the experiment completed an extremely successful year 2020. We celebrate a record telescope efficiency resulting in the largest annual amount of data taken in the history of H.E.S.S..

2020 has been the first full year in the H.E.S.S. extension phase that started with the installation of a new camera on CT5, the world's largest Imaging Atmospheric Cherenkov Telescope (IACT). For this phase the collaboration had set new goals to increase operational efficiency and agility. While the implementation was challenged by global, Covid-19 induced travel restrictions, the high goals that had been set for H.E.S.S. have been met. Not only did the H.E.S.S. telescopes continue observations throughout the pandemic-stricken year - no small feat. The new camera runs flawlessly. Many new features in operations increased the on-target time. As a result the number of observing hours obtained with all telescopes has increased further and reached a new record level.

The new camera on the CT5 telescope (shown here after its arrival in Namibia, © C. Föhr, Heidelberg) worked smoothly throughout its first year on site, contributing to the high telescope efficiency.

2020 has been the most successful year in terms of data-taking in the history of H.E.S.S. The operational efficiency exceeded 95% for the full 5 telescope array for most of the year, with an average telescope efficiency of 98%. In the entire year about 1180 hours of dark-time observations were taken with each of the 5 telescopes. This record level is unrelated to weather conditions, which caused weather losses that were close to the long-term average.

In addition, the collaboration started taking data under moonlight conditions, reflecting the increasing importance of time-domain astronomy for the H.E.S.S. science program. This mode is still in its ramp-up phase and is expected to lead to a further increase of observing time in 2021.

The collaboration does not take for granted all the work that has gone into making sure the operations were smooth and successful, but aims for another high in 2021 and is looking forward to again meet in person and celebrate together.

We mourn the passing of our friend and colleague
January 10, 2021

Friends and colleagues were sad and shocked to learn that on January 9, 2021 Albert Jahnke died in his hometown, Windhoek, in Namibia. Albert, who has joined the local crew of the H.E.S.S. experiment on its Farm Göllschau site in 2006, died of an infection with Covid-19.

The H.E.S.S. Collaboration offers its deepest condolences to the family and friends of Albert Jahnke.

Albert Jahnke graduated from Windhoek and subsequently Technikon in South Africa. He had worked in telecommunication with various schools and enterprises before deciding to combine his profession with his long-standing interest in astronomy. In 2006 he joined the team in charge of operating the H.E.S.S. array on Farm Göllschau. First he was responsible for training the monthly shift-crews of H.E.S.S. members, mostly from Europe, for their four-week observing campaigns. Albert introduced them to the safety regulations, instrumentation and operation of the telescopes and observational procedures and worked alongside with them for the first few nights of the monthly shift. He kept his responsibility for this activity throughout his entire engagement in H.E.S.S. and has worked closely with more than a hundred two-to-three-person shift crews.

Over the years Albert took up other duties, contributed to many installations on the H.E.S.S. site, worked tirelessly on maintaining all hardware components, and cooperated closely with the many teams of the collaboration that are in charge of any subsystem of the array to ensure the proper functioning. He contributed to almost all aspects of local operations. His dedication to H.E.S.S. was outstanding and it has frequently been difficult to prevent him from working overtime well past his term of duty. He was always available to help shift-crews with any problem they might face at any time of the day and often provided advice even from home when being off-duty.

Beyond work in the control-building and with the telescopes, Albert's contribution to life on Göllschau will probably be best remembered for his excellent barbecues. These weekly events were known as highlights in the monthly shifts and very much looked forward to by returning visitors.

Albert enjoyed working for H.E.S.S. and was a devoted, reliable and hard-working colleague who contributed much to the success of the experiment. Following a very difficult year he fell victim to the pandemic during a well-deserved Christmas and New Year break.

He has been a good friend to many members of the collaboration. He will be truly missed.