Dear colleagues,

After 63 years since its establishment on the basis of international cooperation, ESO is now de facto evolving "from world-class to world-leading", in light of the huge progress within its strategy for the 2020s. Let me share with you some achievements and challenges that developed during 2025.

After the great success of the program in the last seven editions, ESO is delighted to announce that the call for applications for the 8th ESO Summer Research Programme is now open. This fully funded program is available to students in STEM fields who have not yet started a Ph.D. program and have completed at least two years of their degree.

The stellar 'Initial Mass Function' (IMF) is a fundamental observable and a crucial component for the understanding of a vast range of astrophysical processes. It is suspected to have its roots in the mass distribution of dense molecular cloud cores resulting from molecular cloud fragmentation, but what shapes this 'Core Mass Function' (CMF) and how core masses really relate to stellar masses, remains unclear. This ESO workshop will summarize and discuss recent observational and theoretical progress on these questions and explore ways forward with ongoing progress in instrumentation (e.g., ALMA upgrade, ELT(s)).

On December 1st, 2025, ESO signed an agreement with a large international consortium for the design and construction of MOSAIC, a Multi-Object Spectrograph for ESO's Extremely Large Telescope (ELT). The consortium is lead by the Principal Investigator Roser Pelló from Marseille Astrophysics Laboratory and includes partners from 14 countries across Europe and beyond. MOSAIC will have complementary capabilities in terms of multiplex, wavelength coverage and spectral resolution compared to the the other instruments under construction for the ELT. 

AGN feedback has become a key element in understanding how galaxies evolve. The time is ripe to discuss what has been learned and plan future lines of research also in the context of upcoming facilities. The workshop will take place on July 6-10, 2026, at the ESO Headquarters in Garching near Munich. Do not miss the chance to present your work and participate in shaping the future of this exciting scientific area! The deadline for abstracts is January 15, 2026.

The expansion of adaptive optics (AO) from an "instrument" concept to a "facility" concept, like the AO Facility (AOF) on UT4, has been a huge success. AO is now routinely used on UT4, enabling exquisite science on the smallest spatial scales while providing more stable image quality during longer exposures. This success, however, has led to a large imbalance in telescope pressure factors in the past few periods with many users wanting to benefit from these assets. To address this hurdle and ensure more highly-rated community proposals get scheduled, ESO is launching several key actions. One of these initiatives is the "Second Generation Deformable Secondary Mirror" project (2GDSM).

After extensive assembly and testing work at the UK Astronomy Technology Centre (UK ATC) in Edinburgh, ESO and the MOONS team are happy to announce that the instrument is ready for shipping. The testing included not only pure performance aspects, but also of operability in Paranal and safety (among others). MOONS will provide exquisite simultaneous optical to near-infrared spectra for close to 1000 locations at a time (either in high or low resolution mode, R=6000 and R=18000 for the H band, respectively). The instrument will be located at UT1 and will be able to reach objects in the whole 25 arcmin diameter field of view of the telescope. Tools have been produced by the consortium and, in collaboration with ESO, embedded in the ESO "ecosystem" to help the community exploit at maximum the capabilities of MOONS, from highly reddened corners of the milky way to the deepest extragalactic fields. 

The latest edition of ESO's Science and Technology Journal, The Messenger, is now available online. This issue 195 focuses on Expanding Horizons, which is the process that ESO has established to define its next major undertaking after the Extremely Large Telescope. Expanding Horizons is an open and inclusive process, in which the whole ESO community is invited to participate. This issue also features an article describing the status of telescopes and instruments that ESO will be providing to the community in the 2030s.

Due to a cooling liquid spillage, UT3 has been out of operations since October 23. The recovery of the affected systems is ongoing, please consult the LPO news page for updates. At the time of writing, the recovery sequence foresees to restart science operations first with SPHERE, then CRIRES and then X-Shooter. The restart with SPHERE and CRIRES is expected to take place in early November, while the X-Shooter recovery will take several more weeks. This is due to the contamination of X-Shooter with cooling liquid that requires careful cleaning and realignment of optical elements. 

Find out more about the Future of UV Astronomy in the Age of HWO meeting. Don't miss your chance to register - the deadline is 5 November 2025. Join the discussions shaping the future of UV science! The workshop will take place on 16 December 2025 at ESO, Garching bei München, extended to a consortium meeting (by invitation) on 15 & 17 December 2025 at the Carl von Siemens Foundation, München.