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 HESS running during this unprecedented time. Thanks to their hard work, the HESS experiment had an extremely successful year in 2020. We celebrate a record telescope efficiency resulting in the largest annual amount of data taken in the history of the HESS experiment.
2020 has been the first full year in the HESS extension phase that started October 2019 with the installation of a new camera on CT5, the world’s largest Imaging Atmospheric Cherenkov Telescope (IACT). For the extension phase of HESS the collaboration had set new goals to increase operational efficiency and agility. While the roll-out and implementation of the upgrades were challenged by global travel restrictions to limit the spread of Covid-19, the high goals that had been set for HESS have been met. Not only did the HESS telescopes continue observations throughout the entire year without interruption – 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 hoeached a new record level. 2020 has been the most successful year in terms of data-taking in the history of HESS. The operational efficiency exceeded 98% for the full 5 telescope array for most of the year, with an average telescope efficiency of 95%. 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 HESS 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 all the work that has gone into making sure the operations were smooth and successful for granted, but aims for another high in 2021 and we is looking forward to again meet in person and celebrate together.