Leiden University led an international research team that produced the deepest low-frequency radio image of the sky to date on Nov. 13, 2026, using the LOw Frequency Array (LOFAR) to observe ELAIS-N1, a northern sky region with little dust, gas, or stars. The LOFAR observatory has studied ELAIS-N1 for years as part of mapping low-frequency radio sources.
The image holds 63,000 radio sources, including quasars and star-forming galaxies, and its resolution is twenty times that of LOFAR’s previous image, the research team said. Modern interferometry made the leap possible, linking radio signals from many telescopes into one sharper picture. The 8-billion-pixel image came from 200 hours of telescope time and 400 terabytes of data. Until recently, handling this much data at such resolution was impossible.
Gains in calibration and data-reduction methods also helped reduce the time needed.
ASTRON researchers and collaborators built the Spider platform, which is hosted at SURF in the Netherlands as a high-performance data processing platform. De Jong reported that Spider handled the full dataset within a few months, cutting processing time by a factor of ten.
LOFAR’s high sensitivity revealed filaments surrounding radio galaxies, particularly near galaxy clusters, along with their structure and spectral characteristics. Getting this detail required mixing high-resolution and low-frequency observations. The sensitivity also lets LOFAR study extended low-frequency radio emissions from active galactic nuclei well.
Quasars are especially dominant in the image. They sit at the centers of bright galaxies, and supermassive black holes power them, with accretion disks producing jets that move at relativistic speeds. The jets stream from the black holes’ polar areas as hot gas and dust and give off radiation. LOFAR is well suited to study them because it detects extended low-frequency radio emissions.
Small, young galaxies with high star formation rates form the other major population in the image, the research team said. Radio waves pass through the gas and dust that obscure visible and infrared light. That gives a clear look at star formation processes inside these galaxies, letting scientists trace how early Universe galaxies developed into today’s larger spiral and elliptical systems.
The sharp detail lets scientists distinguish individual radio sources and massive jets, opening the study of how jets interact with their surroundings and evolve over cosmic time. In previous surveys at lower resolution, distant galaxies and their jets looked like little more than featureless blobs, making single galaxies hard to distinguish from clusters. The new view provides fresh opportunities to study these interactions.
LOFAR’s design supports the deep view. Researchers said the telescope has 38 stations in the Netherlands, joined by 14 international stations across Europe, and that the farthest stations sit nearly 2,000 kilometers apart. The LOFAR European Research Infrastructure Consortium brings together expertise from the Netherlands, Germany, France, the United Kingdom, Poland, Italy, Sweden, Ireland, Latvia, and Bulgaria. This creates one of the world’s largest, most sensitive, and highest-resolution radio telescopes.
Processing the data demanded new techniques that precisely fix severe distortions from Earth’s ionosphere, the electrically charged layer of the upper atmosphere. Dr. Cyril Tasse of the Paris Observatory led work on the algorithms, and robust automation and optimization made it possible to study 13,000 hours of observations.
On Feb. 19, 2026, an international collaboration using LOFAR published LoTSS-DR3, a detailed radio sky map of 13.7 million cosmic sources. It is the most complete count yet of supermassive black holes that are actively growing. The findings will appear in Astronomy & Astrophysics. The survey shows a dramatically different view of the universe than optical wavelengths, with emission largely from relativistic particles moving through magnetic fields.
The release drew on more than ten years of observations, processing, and analysis, and it needed continuous processing and monitoring over many years and more than 20 million core hours of computing time. Pulling data from telescope archives and sharing computing work across many high-performance systems created another challenge. Alexander Drabent of Thuringian State Observatory called the data volume immense. Square Kilometer Array Observatory scientist Dr. Wendy Williams said, “LoTSS-DR3 is not an endpoint, but a major milestone.”
New processing methods now make it practical to image survey data at far higher resolution. The collaboration plans to build upon LoTSS-DR3.
The radio data will be especially useful when combined with optical, infrared, and X-ray observations of the same patch of sky to determine properties such as the distance and mass of each radio source. Astronomers can use multi-wavelength observations to characterize each radio source. This complements the LOFAR image and supports studies of distant galaxies and black holes.
The research team says the work demonstrates the potential of LOFAR2.0. ASTRON is developing LOFAR2.0 with European partners, so the telescope can produce wider, higher-resolution images. LOFAR is currently undergoing the upgrade, which offers a two-fold increase in survey speed.
The Square Kilometer Array will combine South Africa’s MeerKAT array with the Inyarrimanha Ilgari Bundara site, also called the Murchison Radio-astronomy Observatory, in Australia. The upgrades are intended to keep LOFAR competitive with next-generation radio telescopes such as the Square Kilometer Array.
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