LST-2’s Camera Support Structure was successfully installed on the North site of CTA observatory
On Thursday 3 July 2025, the Camera Support Structure (CSS) for the second Large-Sized Telescope (LST-2) was successfully installed on the North site of the Cherenkov Telescope Array (CTA) Observatory in La Palma, Spain.
A large structure to support the telescope's camera
The CSS is a composite structure responsible for holding the camera steady at its focal distance. It is composed of a carbon-fibre arch made of six tubes and a camera frame that secures the telescope’s camera, both designed and produced by LAPP (Laboratoire d’Annecy de Physique des Particules). The whole structure is reinforced by a set of 26 carbon-fibre tension rods.
Following months of ground-level assembly and preparation, the teams used a 75-metre-high crane to lift and position the arch on the telescope. Rope access techniques were then employed by the LAPP team to fine-tune the fittings along the arch before the crane was released. The operation concluded with the tensioning of all 26 rods.
This achievement marks the installation of the final mechanical component of the LST-2, the last of four LSTs (Large-Sized Telescopes) currently under development on the La Palma site. The optical systems, including the mirrors and camera, will be installed next.
Meanwhile, tests on the LST-4 drive system, which began several months ago, have continued to progress. The camera was installed a month ago, marking an important step towards commissioning the telescope.
LAPP's participation in CTAO
LAPP is heavily involved in the construction of the CTA observatory’s large telescopes, the LSTs (Large-Sized Telescopes), which are designed to capture lower-energy events and study transient phenomena. For example, LAPP is working on the detection of gamma-ray bursts, as well as on observations of the eruptions of active galactic nuclei.
The Astronomy-Gamma team at LAPP is responsible for producing the arch of the LST telescopes supporting the camera, all in composite materials. It is also developing the telescope motion and computer control system and optimising communications between the software environment, programmable logic controllers and other on-board devices.
LAPP is also involved in generating alerts for rapid observations, carrying out high-performance analysis projects and projects based on machine learning techniques, as well as off-site computing and data archiving.
In 2019, a team from LAPP was awarded the Cristal collectif by the CNRS for its contribution to the design and construction of the large telescopes (LST) at the CTAO observatory.
More information :
- News on the CTAO website: https://www.ctao.org/news/the-lst2-mechanical-structure-completed-with-installation-of-the-camera-support-structure/
- CTAO website: https://www.ctao.org/
- CTA at LAPP: https://www.lapp.in2p3.fr/en/research/cta
- Cover photo: The large telescopes at the CTA observatory. Credit: Armand Fiasson (LAPP)