News
4MOST Social Media Launch
2025-09-18
The Science Communication working group are excited to announce that 4MOST is now active on multiple social media platforms. You can now follow 4MOST on LinkedIn, Bluesky, and Instagram to stay up to date with news, project updates, behind the scenes insights, science highlights, and learn about the team behind it all.
Find us here:
We are excited to share with you the work being done across the 4MOST community!
4MOST installation on VISTA
2025-09-12
In June 2025 the last subsystems of 4MOST were shipped from the AIP, Germany, to Paranal, Chile. We are glad to report that all of the shipments arrived safely at the VISTA telescope and that 4MOST in its entirety is now at Paranal.
With the arrival of the final shipments at Paranal, installation of the various subsystems has been carried out by the many specialist teams. The metrology system that monitors the fibre spine positions was installed and calibrated using the focal surface test tool. The test tool was then removed from the focal plane and the team from AAO reintegrated, tested, and installed the fibre positioner onto the telescope. A team from MPIA then installed 4MOST's electronic cabinets and wiring for all of the systems. Finally, the cassegrain cable wrap and the almost 2500 fibres were installed, with the fibres being connected to the fibre positioner.
The recent shipments also included the two low resolution and the high resolution spectrographs. As these were dismantled for shipping, they have been reassembled and aligned in the New Integration Hall at Paranal Base Camp by teams from CRAL and AIP. The two low resolution spectrographs have been reassembled and tested, meeting all of their specification requirements and even exceeding many. On the 5th and 7th of September the low resolution spectrographs were craned into the VISTA dome and installed side by side under the main telescope platform. The high resolution spectrograph currently remains in the New Integration Hall for final checks before being installed on VISTA in the coming weeks.
To demonstrate the hard work that has been taking place at Paranal, Allar Saviauk has produced a short film documenting the recent installation work. The film can be viewed at https://cloud.aip.de/index.php/s/3GF8B3jQiKbTbec.
With the installation of 4MOST nearing completion, we now look forward towards celebrating everyone's hard work with 4MOST's first light!
ESO Picture of the Week: Fantastic 4MOST
2025-07-23
On the 22nd July 2025, 4MOST featured in ESO's picture of the week. With work well underway to install 4MOST on VISTA, we were treated with an image of the installed fibre positioner, with the backlit fibres positioned to create the Fantastic 4 logo.
In addition to the image, ESO and 4MOST released a video showing the fibre positioner in action as it created the iconic logo. It reveals the precise and coordinated motion of the 2436 fibres as they moved gracefully into place.
ESO's picture of the week article, image, and video can be found at:
- Article and image: https://www.eso.org/public/images/potw2529a/
- Video: https://www.eso.org/public/videos/potw2529a/
This marks an exciting milestone in 4MOST's journey, highlighting the tremendous work and dedication from everyone involved over the years. A huge congratulations!
4MOST Milestone: Second Major Shipment to Chile
2025-06-18
On the 9th May 2025, ESO gave the green light to start packing some of the subsystems at the AIP, Germany, for shipment to Paranal, Chile.
Work began on detatching the fibre system from the fibre positioner and removing the fibre slits from the spectrographs. The smaller subsystems (detectors, fibre feed, electronics cabinets, calibration system, metrology, and secondary guiding) were then shipped by airfreight on the 20th May and safely arrived in Santiago, Chile, on the 29th May.
On the 13th June, ESO and the 4MOST consortium held a meeting regarding preliminary acceptance in Europe (PAE). 4MOST successfully passed PAE, initiating the final shipment which predominantly contains the spectrographs.
With the AIP integration hall now looking rather empty, we are one step closer to the start of operations. In the coming months, we look towards installing and commissioning 4MOST on VISTA.
SITCOM Observing School
2025-04-22
During the week beginning 7th April, nine members of SITCOM were hosted at the Astrophysical Observatory of Asiago for an observing school. For some members the school provided them with their first observing experience, while it gave other members a chance to refresh their observing knowledge.
During the school the team learnt the basics of observing, including how to determine if and when a target is most optimal to observe, the calibration data that is required for the data reductions, how to setup and observe using the 1.22m Galileo telescope at the Astrophysical Observatory of Asiago, and finally how to reduce the observations.
How many astronomers does it take to observe a galaxy? (Credit Marica Valentini)
Using what they had learnt, they planned and executed three nights of observations using the 1.22m Galileo telescope. The team observed a number of targets including galaxies such as NGC4565 and M104, planetary nebular, binary stars, and transient events. In particular, the group observed three objects of high interest: Nova X SER, T Corona Borealis, and an unclassified supernova-like transient. The unclassified transient was initially classified as a supernova II and continues to be monitored by staff at the Astrophysical Observatory of Asiago.
The attending SITCOM members thank Marica Valentini for organising the school, and to the staff at the Astrophysical Observatory of Asiago for hosting.
Science Team Meeting 2025
2025-03-13
The most recent 4MOST Science Team Meeting took place on February 24th-28th 2025 at the University Federico II, Italy, and online.
As 4MOST nears the start of operations, this meeting focused on the ongoing and future preparations required for a successful survey start. There were many in-depth discussions surrounding the survey strategy and simulations, with surveys communicating and converging on the future progression of the strategy and simulations. Plans for the phases leading up to the start of operations were discussed, with sessions focusing on the plans for commissioning and operation rehearsals.
Although the meeting primarily focused on the technical preparations, there were also sessions focused on science. There were discussions regarding the plans for DR0, the publication process, and the communication of 4MOST science to public audiences. Additionally, the wide range of science talks displayed the ongoing and future science projects that 4MOST will facilitate. All available presentations and recordings can be found on Docushare.
Overall, this science team meeting was a success, although it highlighted that there is still plenty of work to be done before the start of operations.
4MOST Wide Field Corrector checks out
2025-03-06
During the 4MOST hardware integration campaign on Paranal in October 2024, one of the verification measurements done on Paranal during the incoming inspection was the measurement of the Wide Field Corrector optical throughput. At the time, the result of this measurement indicated a loss of optical throughput compared to reference measurements done in Potsdam before shipment. Nevertheless, the WFC was installed on the VISTA telescope and telescope re-commissioning has been ongoing since then.
Possible reasons for the measured loss of throughput have been intensively investigated over the past months, however, since we had no physical access to the WFC, it was not possible to make tests to better understand the root cause of the problem. After discussions between the Consortium and ESO, it was decided to remove the WFC from the VISTA telescope and move it to a clean room on Paranal to investigate the issue. Removing the WFC from the telescope is a complex procedure involving removal of the Cable Wrap system (CaCW), the 4MOST test camera (FSTT), the Guiding and WFS unit, and finally the WFC itself. On 2 March 2025, a team from AIP arrived on Paranal to carry out this work in collaboration with ESO staff.
On 4 March 2025, the WFC optical throughput was re-measured. We are very pleased to report that the results confirm the Potsdam measurements, and the WFC performance is now verified to be nominal and in specifications. Over the next couple of days, we will reinstall all the components on the telescope and the final steps of VISTA re-commissioning can be carried out as planned.
We used the opportunity in the clean room to clean the L1 front and L4 back surfaces with CO2 snow to remove fine dust, as shown in the photo below.
First Technical Light with new Wide Field Corrector and Aquisition & Guiding systems
2024-12-05
4MOST First Technical light image: NGC2207 and IC2163, a pair of overlapping and probably interacting spiral galaxies at about 17 Mpc (55 million light year) distance, surrounded by much nearer stars in our own Galaxy. (Credit: 4MOST Consortium and ESO)
Following the successful 4MOST Paranal installation campaigns in October and November, on November 22 the Consortium and ESO met for the VISTA telescope re-commissioning readiness milestone. The purpose of this milestone was to verify that the VISTA telescope is ready for re-commissioning with the new 4MOST hardware. Once the new Wide Field Corrector and the Acquisition & Guiding and Wave Front Sensing systems have been fully characterized and commissioned, the VISTA telescope will be ready for installation of the remaining 4MOST subsystems, which in turn means start of formal 4MOST verification and commissioning.
We are pleased to report that the November 22 readiness review was successful, which allowed for the start of telescope recommissioning on November 24. It is very exciting to see the VISTA telescope back on sky after being dormant for quite a while. The testing of the telescope has now reached a point where we were able to make images on the technical cameras. With this message, we are delighted to share the official 4MOST “First Technical Light” image with you. The image, taken during the night of December 5, shows the galaxy NG2207. Image quality is already very good, which gives us great confidence in the performance of the VISTA telescope in the new 4MOST configuration.
The amount of work done, enabling the project to reach this milestone, is nothing short of amazing. On behalf of our entire team, we extend our deepest gratitude to each member of the consortium and the ESO support team for your support and dedication. Reaching this significant milestone would not have been possible without your collective efforts, expertise, and commitment.
Looking forward to the next exciting steps towards completing 4MOST!
Joar and Roelof
First 4MOST subsystem installed on VISTA
2024-06-12
On Sunday, June 9, the first 4MOST subsystem was installed on the VISTA telescope on Paranal. This was the 4MOST Cassegrain Cable Wrap, aka CaCW, which is a deliverable from AIP with contributions from MPIA. As this subsystem is quite large and heavy, and therefore must be shipped by sea containers, ESO agreed to ship it in advance of the PAE-1. The two sea containers arrived safely at Paranal on April 19.
On June 3, a team from AIP Potsdam and ESO Garching arrived on Paranal for the unpacking, inspection, re-integration and finally installation of the CaCW on the telescope. The work on site went quite well, and we were able to install the CaCW on the telescope on June 9, slightly ahead of schedule. With the very efficient and competent support from ESO, the work went quite well without any major issues.
We were able to gain quite a lot of experience from this mission in terms of shipping, logistics, planning, and collaboration with ESO on site. It gives us great confidence for the upcoming shipments and installation activities. Many individuals have contributed to making this happen, and it is a very important milestone for the project.
The 4MOST PI Roelof de Jong said: ''I am very happy to see the first 4MOST subsystem installed on the VISTA telescope. That everything went so smoothly gives great credit to the entire team that developed the subsystem and planned its shipment and installation. It also bodes well for future deliveries, where I look forward to further shipments later this year.''
Appointment of a new S9 survey co-PI
2024-02-29
The 4MOST Principal Investigator, Roelof de Jong, is pleased to announce that the 4MOST Executive Board has unanimously approved the appointment of Lara Cullinane as a new Survey co-PI of The Thousands and One Magellanic Clouds fields Low and High Resolution Survey (1001MC; S9). Lara is joining S9 Survey PI Maria-Rosa Cioni, who has been leading the Survey from inception and is also based at the AIP.
Lara works in the fields of near-field cosmology and (extra-)galactic archaeology, with a particular interest in dwarf galaxies. She received her PhD from the Australian National University (ANU) studying the outskirts of the Magellanic Clouds, placing some of the first kinematic constraints on ancient interactions between the two galaxies. Before joining the AIP and 4MOST, she was a postdoc at the Johns Hopkins University (JHU).
Lara will bring expertise in both optical spectroscopy and survey operations to S9. 4MOST data will provide an unparalleled view into the history of the Magellanic system and its effects on the Milky Way, and Lara is excited to be on the forefront of this exceptional new discovery space.