On 3 July, the CTAO LST Collaboration successfully installed the camera support structure (CSS) on the LST-2, one of the three Large-Sized Telescopes (LSTs) currently under development on the CTAO-North site in La Palma, Spain. The CSS is a composite structure comprising a carbon-fibre arch made of six tubes and a camera frame that secures the telescope’s camera. With the CSS now in place, the LST-2’s mechanical structure is complete, paving the way for the integration of the optical elements.
The CSS is responsible for holding the camera, which measures 3-by-3 metres and weights 2.5 tonnes, steady at the so-called focal distance, even as the telescope moves. The focal distance is the precise point where all the reflected Cherenkov light converges and can be captured for analysis. For the LSTs, this distance is approximately 28 metres, about the height of a ten-story building.
The robust CSS, including the parabolic arch and camera frame, was designed by the LST team at LAPP (Laboratoire d’Annecy de Physique des Particules) in France. This system is made of carbon fibre to keep the large structure stable and light, enabling rapid repositioning of the telescope while minimising shadowing of the camera.
To reinforce and stabilise the CSS, the LST team at INFN (Istituto Nazionale di Fisica Nucleare, Italy) also installed a set of 26 carbon-fibre tension rods. With the full system in place, the camera remains extremely stable, shifting by less than 3 cm sideways and less than 1 cm towards the mirrors, even when the telescope is pointing directly upwards at the zenith.
The installation on 3 July was coordinated by both teams. 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 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, which now enters the integration phase, during which the optical systems, including the mirrors and camera, will be installed.
The CTAO LST Collaboration is an In-Kind Contributor (IKC) for the Observatory, in charge of building the Large-Sized Telescopes (LSTs). The collaboration is made up of over 400 scientists and engineers from 67 different institutes across 11 countries: Brazil, Bulgaria, Croatia, Czech Republic, France, Germany, Italy, Japan, Poland, Spain and Switzerland.
Congratulations to the LST Collaboration for this milestone!
