A time-lapse of the universe in more detail than ever before: that's the aim of the NSF-DOE Vera C. Rubin Observatory in Chile, which will unveil its first images of the night sky on 23 June. Researchers at Leiden Observatory have played a major role in making it all possible.
The first images will offer an early look at just how powerfully Rubin's enormous camera performs, says Leiden-based researcher Henk Hoekstra. 'The combination of quantity and quality is remarkable. What really makes this special is that we'll be creating a ten-year time-lapse, with snapshots taken every three to four days.' Thanks to its massive camera, the observatory will be able to capture extremely faint objects spread across vast areas of the cosmos.
The observatory is located on Cerro Pachón, a mountain in central Chile, and will repeatedly scan the universe over the next decade using the world's largest digital camera. It is named after Vera C. Rubin, the American astronomer who provided the first convincing evidence for the existence of dark matter.
Watch parties around the world - including in the Netherlands
All over the world, watch parties are being organised to celebrate the first images from the Rubin Observatory. In the Netherlands, scientists involved in the Rubin mission, along with students and other astronomy enthusiasts, will gather at Sonnenborgh Museum and Observatory in Utrecht to mark the occasion.
Dutch expertise has played a key role in the Rubin project. Programme manager Elisa Chisari (Utrecht University) brought together colleagues from Utrecht, Leiden and Groningen to make a meaningful contribution. Researchers from Leiden University developed a critical piece of hardware called DREAM (Dutch Rubin Enhanced Atmospheric Monitor): an advanced observing system that monitors cloud cover in real time. The system helps the telescope choose the best direction to observe.
Rescuing valuable data by avoiding cloud cover
The DREAM system takes a full-sky image every six seconds and tracks the brightness of some 6,000 stars to measure how clear the sky is. 'Although the Rubin Observatory is based in Chile because of its generally excellent weather, around 5 to 10% of nights are still partly cloudy,' explains Hoekstra. 'If we know where the clear patches are, we can still collect useful data.'
Thanks to the system - installed in Chile by Remko Stuik - it's possible to salvage observations that would otherwise be lost. The team estimates that DREAM could recover roughly 5% of data that would have been missed. 'For a billion-dollar project, that's an extra $50 million worth of science,' says Hoekstra. In addition to its technical function, the DREAM project also gives researchers access to scientific data: six of the eight Dutch astronomers involved in Rubin are based in Leiden.
DREAM is based on technology from the MASCARA project, developed in Leiden to detect planets around other stars. That earlier project was led by Ignas Snellen. According to Hoekstra, DREAM stands out for its quality and reliability, which is why the Rubin team approached Leiden. Snellen adds: 'It's fantastic to see MASCARA technology finding a second life in this state-of-the-art observatory.'
The Dutch Rubin programme
The Dutch contributions to the Rubin Observatory involve researchers from Leiden University (PIs: Henk Hoekstra, Koen Kuijken, Sjoert van Velzen, Remko Stuik, Anthony Brown and Joop Schaye), the University of Groningen (PI: Amina Helmi) and Utrecht University (PI: Elisa Chisari). Together, they contribute to the observatory and its many scientific collaborations, bringing expertise in data processing and analysis, hardware, and modelling.
