4MOST - 4-metre Multi-Object Spectroscopic Telescope
4-m Multi-Object Spectroscopic Telescope


First 4MOST subsystem installed on VISTA


VISTA telescope with CaCW installed. (Credit: Allar Saviauk)

The installation team from AIP, ESO Garching, and ESO Paranal in front on CaCW installed on the VISTA. (Credit: Joar Brynnel)

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


Lara Cullinane, new co-PI of the S9 survey.

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.

4MOST Milestone: First Major Shipment to Chile


Credit: AIP/Allar Saviauk.

On Thursday, February 29, the Cable Wrap - the largest physical subsystem of 4MOST - commenced its journey from AIP's facilities to ESO's Paranal Observatory in Chile.

"The decision to ship the Cable Wrap early marks a crucial step forward for the project. Rigorously tested by us and by ESO, and meeting all requirements, the subsystem will be installed on the VISTA telescope ahead of the next major 4MOST shipments to Paranal," says 4MOST project manager Joar Brynnel. "This proactive approach not only optimises space in the AIP integration hall but also accelerates the overall timeline, ensuring timely integration and deployment."

Two sea containers, meticulously packed and components wrapped to shield against dust and humidity, will be handed over to shipping partner DSV. Equipped with a crane for efficient loading, a large truck will transport the containers to the harbour of Hamburg, where they will be embarked onto a large ship bound for Chile. The voyage, spanning five weeks via the Panama Canal, will then continue on trucks via the Pan-American highway and culminate in the delivery of the Cable Wrap to Paranal Observatory.

Read more in the AIP press release and watch a video of the final test phase and first shipment at https://youtu.be/IN__wXps5Rg.

Successful Science Team Meeting


On site participants in front of the University Hall of Uppsala University.

The 4MOST Science Team Meeting, which took place from 12-16 February, was a great success, with a record 217 registered participants, either in person at Uppsala University, Sweden, or online.

This was likely the last in-person meeting before 4MOST sees first light and it therefore was key in shaping the future of the Project. It allowed survey teams to converge and delve into discussions on survey strategy and operations before the submission of the Survey Management Plan. It also provided a golden opportunity to plan and discuss the first technical and science papers.

In addition to plenary sessions discussing topics such as survey simulations, commissioning plans, or DR0 science and papers, there were several breakout sessions about the various infrastructure working groups, the various other 4MOST working groups, as well as on galactic and extragalactic science. All available presentations can be found on Docushare.

Some of the online participants on 15 February.

"First sky-light" for 4MOST fibres and spectrographs


Science slit integration from the side into LRS-A.

As part of the 4MOST assembly, integration and test (AIT) activities in the AIP integration hall, the science fibre-slits were installed into the Low-Resolution Spectrographs (LRS-A and LRS-B) and the High-Resolution Spectrograph (HRS), replacing the previous test-slit-units, reports LFF Workpackage Manager, Andreas Kelz.

Using various lamp sources and the 4MOST calibration system, exposures were taken to obtain both continuum and emission line spectra. These spectra have been successfully processed by the 4MOST QC1 pipeline to verify the spectrograph performance in wavelength coverage, spectral resolution, and image quality (FWHM) with the final fibre-slits in place.

"The installation of the science slits went smoothly and judging from the first impression, the performance of these final slits seems excellent, thanks to the entire team that developed, built and carefully measured the slit assemblies", said Kelz. More detailed analysis with respect to the three spectrograph arms (i.e., the blue, green, and red channels) is ongoing.

Using an addition setup, skylight was coupled into the fibre system. For the first time, hundreds of solar spectra were obtained with 4MOST - and the fibres and spectrographs have been "on-sky"!

Please see the attached photos courtesy of Andreas Kelz (AIP).

Science slit integration from the top into HRS.

Skylight (solar) spectra recorded with the LRS blue, green and red cameras (from top to bottom).

Skylight (solar) spectra recorded with the HRS blue and green cameras (from top to bottom) with ThAr light in the simultaneous calibration fibres.

Science Team Meeting 2024


The University Hall of Uppsala University.

The next 4MOST Science Team Meeting is now open for registration. It will take place in Uppsala on 12-16 February 2024. Participants can follow the sessions online or in person. Please see http://4mmosst.wikidot.com/science-team-meeting-february-2024 for more details.

The science that 4MOST will enable is at the core of this meeting. We therefore invite all participants (online and in-person) to submit suggestions for contributed talks, including title and abstract, using a Google form. These should not be the usual survey-presentation talks, but rather focus on a specific science question that 4MOST data will help address, and can be connected to ongoing research projects with other surveys and instruments. There is also a possibility to submit general suggestions for the meeting agenda using the same Google form. Your input will help us develop the programme, so we kindly request that abstracts/feedback are sent before 8 January.

Congratulations to Kate Maguire


Kate Maguire

The 4MOST Project congratulates Kate Maguire from Trinity College Dublin for being awarded an ERC Consolidator Grant, CosmicLeap, to explore the deaths of white dwarfs, mapping the full diversity of ways in which these bodies explode. This will be crucial for defining new precision samples for cosmology, as well as determining the rates and contributions of white dwarf explosions to the origin of the elements.

"One of the key aims of the project is to obtain rapid spectroscopy of the largest sample of white-dwarf transients to date," explains Kate. "The first days after explosion are when the signatures of their diversity is greatest and these spectra will be crucial for distinguishing between explosion scenarios. I'm excited to work closely with the 4MOST team and members of the S10 Time Domain Extragalactic Survey (TiDES) to achieve my research aims."

Kate obtained her PhD from Queen's University Belfast before taking up a post-doctoral research position at the University of Oxford. She held Marie Skłodowska-Curie and ESO fellowships at the European Southern Observatory headquarters in Munich from 2013-2015 and an Ernest Rutherford Fellowship at Queen's University Belfast from 2015-2019. She is currently an Associate Professor at Trinity College Dublin.

Congratulations to Ása Skúladóttir


Ása Skúladóttir

The 4MOST Project congratulates Ása Skúladóttir from the University of Florence for being awarded an ERC Starting Grant for her research project studying the origin of the Milky Way and its chemical elements. Ása is the Survey PI of 4DWARFS (4MOST survey of dwarf galaxies and their stellar streams) and this ERC Starting Grant will enable her to build a strong team to analyse the 4MOST data of her Survey.

"Like all larger galaxies, the present Milky Way was formed through a sequence of mergers of smaller dwarf galaxies over its lifetime," explains Ása. "Around our galaxy there are now dozens of known dwarf galaxies as well as 'stellar streams' – streams of stars that we think are associated with old dwarf galaxies that were destroyed during their interaction with the Milky Way."

Ása's ERC project, 'TREASURES', will combine data from Gaia and from the 4DWARFS Survey to study individual stars of various ages, thereby tracking the evolution of the Milky Way and its chemical enrichment throughout cosmic time. "The data," Ása further explains, "will also provide an opportunity to investigate the hierarchical formation of the Milky Way and provide the most complete overview of the evolution of dwarf galaxies, reconstructing their histories: from formation to disintegration."

Ása Skúladóttir is from Iceland. After obtaining her PhD in Astronomy in 2016 at the Kapteyn Institute of the University of Groningen, she worked as a post-doc at the Max Planck Institute for astronomy (MPIA) in Heidelberg, Germany, from 2016-2019. She then joined the University of Florence, first as a post-doc, and since early 2021 as RTD-A (equivalent to an Assistant Professor).

Long Fibre Feed installation at CTS and connection to AESOP


The 4MOST Fibre System, deployed at the Cassegrain Test Stand (CTS) at AIP. On the ground is the fibre strain relief assembly and the three transport cases for the slit assemblies. The elevation chain connects to the CTS structure and the fibre route continues inside the cable rotator.

The 4MOST System Integration is proceeding nicely according to plan. On 19 July 2023, the final optical fibre relay with all the science and auxiliary fibres (aka, the Long Fiber Feed or LFF) was connected to the Fibre Positioner AESOP. This is an important milestone on the path towards full system integration in Potsdam. Please see the attached photos courtesy of Andreas Kelz (AIP).

"After the Fibre-Feed system has been built and assembled, it successfully passed Local Acceptance Review in May 2023," said LFF Workpackage Manager, Andreas Kelz. "Subsequently, the fibre system was folded, packed and transported across the AIP campus to the main integration hall, where it has been integrated into the Cassegrain Cable Wrap and mounted onto the Cassegrain Test Stand. The fibre elevation chain and strain relief units are mounted in the same positions as on VISTA. Finally, all 181 fibre connectors have been plugged to the backside of the AESOP positioner."

All fibre connectors (i.e., the 168 for science fibres, 12 guide cables and 1 fiducial connector) are plugged to the backside of the AESOP positioner. Also, all service cables and cooling lines (three o'clock) are connected to AESOP and the limit switches.

Unique view of the 4MOST focal plane


Amazing view of the 4MOST focal plane as seen through the Wide Field Corrector. You can access here a high-resolution version of the image.
Courtesy of Michael Schroeck (AIP)

This photo was taken in the AIP Integration hall on 19 July 2023. It shows an amazing view of the 4MOST focal plane as seen through the Wide Field Corrector (WFC) from the perspective of the telescope’s secondary mirror. The hexagonal pattern of bright dots in the centre shows the area of the AESOP spines. Just outside the spines, visible as bright squares,  one can recognise the six technical CCDs (guiders and wavefront sensors) through their pickup prisms. The bright rings are the fiducials used by the 4MOST metrology system to precisely measure the position of the spines. One can also spot the baffles inside the WFC as faint concentric rings outside the focal plane.  

This is a rare occasion to enjoy such a view. It further demonstrates that 4MOST is complete and ready for verification in the AIP Integration hall!