Data for the catalogue was collected over 200 nights between 2015 and 2019 using the PAUCam camera, mounted on the William Herschel Telescope in La Palma. The catalogue is now accessible through the PAUS website and the CosmoHub web portal.

Spanning a massive 50-square-degree region of the sky, equivalent to about 250 full moons, the catalogue includes information on 1.8 million astronomical objects. This vast dataset will allow astronomers to generate highly accurate cosmic maps, which are essential for understanding the formation of structures in the Universe and for the study of dark matter and dark energy.

Professor Enrique Gaztanaga, Director of the PAUS Survey and member of the University of Portsmouth's Institute of Cosmology and Gravitation, commented: "The PAU Survey offers a groundbreaking approach to creating cosmic maps, made possible through the design and development of a novel instrument and a dedicated survey to collect and analyse data in ways never done before. It has been a privilege to collaborate with such a talented and dependable group."

The accelerated expansion of the Universe, largely driven by dark energy - making up around 70% of the cosmos - remains one of astronomy's biggest enigmas. The PAUS catalogue aims to shed new light on this mystery, offering a comprehensive and accurate characterisation of galaxies at distances exceeding 10 billion light years.

This resource will be highly beneficial to the astronomical community, providing key data for both scientific analysis and the calibration of other cosmological surveys.

The PAUCam camera was specifically engineered to accurately determine galaxy distances, allowing astronomers to study the expansion of the Universe under the influence of dark matter and dark energy. The project builds upon earlier surveys, including the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) and the Kilo-Degree Survey (KiDS), combining datasets to produce highly accurate distance and time information for deep-space objects.

This extensive catalogue represents a major leap forward in cosmic research, offering photometric redshift measurements that allow astronomers to determine the distances of galaxies as they appeared billions of years ago.

To achieve these measurements, the PAU camera uses 40 colour filters across the optical spectrum, photographing each field multiple times through different filters. This approach captures the redshift effect, which causes light from objects moving away from us to shift toward the red end of the spectrum. Redshift is a crucial factor in calculating the distance of cosmic objects from Earth.

David Navarro-Girones, a PhD student at ICE-CSIC and lead author of one of the papers released noted: "The precision in measuring galaxy distances depends on the number of filters you use, as each filter provides different information about the galaxy. The great advantage of PAUS is that it combines information from 40 different filters, allowing for highly accurate distance measurements. This level of precision is crucial for the study of the structure of the universe, which in turn requires data from a large number of galaxies."

Details of the new catalogue are described in two articles published in the 'Monthly Notices of the Royal Astronomical Society' (MNRAS). One article focuses on measuring galaxy distances, while the other outlines the calibration process of the PAUS data.

In the coming months, the PAUS team plans to present ongoing studies on galaxy clustering and the alignment of galaxy shapes, further contributing to our understanding of how the Universe formed and evolved.

Related Links
The Physics of the Accelerating Universe Survey
Understanding Time and Space