INAF Arcetri Journal

The monthly newsletter of the INAF Astrophysical Observatory of Arcetri

January 2025 | Issue 1

The PNRR-funded STILES project foresees the installation of 64 new receivers (covering the frequency band called 5B, between 8.4 and 15.3 GHz) in the MeerKAT antennas. These radio telescopes are operated by the South Africa Radio Astronomy Observatory and will be integrated in SKA-MID in the coming years.
The Max Planck Institute for Radio Astronomy (MPIfR) has been awarded by INAF for the supply of 64 (+ 2 spare) receivers. The MeerKAT Band 5B receiver is composed of a chain of microwave components mainly consisting of a passive feed-system (circular horn antenna, marker coupler and ortho-mode transducer), two low noise amplifiers (one for each polarization) and a section for further RF conditioning of the signals.
The passive components and the two low noise amplifiers of the front-end are inserted in a cryogenic environment to ensure excellent receiver noise temperature performance. The aggressive schedule of the PNRR funding scheme dictated the acceptance of the first receiver to be executed by the end of 2024. The first receiver was first validated at the MPIfR laboratory during the Factory Acceptance Test (middle November) and then at the operational site in South Africa at the Site Acceptance Test (middle December, see picture below). The MPIfR is now proceeding with the series production to deliver all receivers at the site by November 2025.

Technical Director: Pietro Bolli

Testing activities are started in the ADONI optical laboratory on the LATT mirror! The LATT is a prototype of an active mirror for space telescopes, controlled by 19 voice coil actuators. The working principle is shared with its bigger brothers the LBT and VLT adaptive mirrors, based on an optical surface "floating" in front of the support when in operation.

Laboratory tests include electromechanical and optical characterization at different "floating" distances (or gap) and, more important, in rough vacuum. Air shall in facts be removed from the gap to reduce the mechanical coupling with the support; to this purpose, a stylish plexiglass vacuum chamber (the Vacquarium) has been procured and installed in the lab, housing the LATT.

You are welcome to come and participate to the tests, but please do not slam the doors!

Coordinator: Runa Briguglio