Advanced X-rays Uncover Long-Lost Star Map in Menlo Park

Scientists at SLAC National Accelerator Laboratory use synchrotron technology to detect traces of ancient Greek astronomer Hipparchus' star catalog.

Published on Feb. 13, 2026

Got story updates? Submit your updates here. ›

Researchers at SLAC National Accelerator Laboratory in Menlo Park, California are using advanced X-ray technology to uncover a long-lost star map created by ancient Greek astronomer Hipparchus. The team is analyzing pages of the Codex Climaci Rescriptus, a medieval manuscript, in hopes of recovering Hipparchus' star catalog that has been hidden for over a millennium.

Why it matters

Recovering Hipparchus' star catalog would provide valuable insights into the birth of modern science, as it represents one of the earliest attempts to comprehensively map the night sky. The findings could also help settle a longstanding debate over whether the Roman astronomer Ptolemy plagiarized Hipparchus' work.

The details

Scientists at SLAC are using high-energy X-rays from a synchrotron particle accelerator to detect traces of the original ink used by Hipparchus, which contained more calcium than later inks. This allows them to identify the older writing beneath newer text in the Codex Climaci Rescriptus, a palimpsest manuscript where the original text was scraped off and reused. Researchers have already identified full illustrations believed to be part of Hipparchus' star map.

  • On January 23, 2026, a SLAC spokesperson said researchers had identified full illustrations believed to be part of the star map.
  • In early February 2026, researchers from the Museum of the Bible, University of Washington, CNRS, and Stanford University spent a week scanning 11 pages of the Codex Climaci Rescriptus at SLAC, working 24 hours a day.

The players

SLAC National Accelerator Laboratory

A U.S. Department of Energy national laboratory located in Menlo Park, California that operates a synchrotron particle accelerator used in the research to uncover Hipparchus' star map.

Hipparchus

An ancient Greek astronomer who is believed to have created a comprehensive star catalog around 100 BCE, which has long been lost to history.

Victor Gysembergh

A researcher at the French research institute Centre National de la Recherche Scientifique (CNRS) and the lead scholar on the project to recover Hipparchus' star map.

Keith Knox

An imaging scientist with the U.S.-based nonprofit Early Manuscripts Electronic Library who is part of the team working to uncover the lost star map.

Ptolemy

A Roman astronomer whose star catalog has long been compared to Hipparchus', leading to debates over whether he plagiarized Hipparchus' work.

Got photos? Submit your photos here. ›

What they’re saying

“If you take high-energy X-rays and hit iron, it absorbs them and then radiates X-rays at a lower wavelength. We detect those wavelengths and get a picture of where that metal is.”

— Keith Knox, Imaging Scientist (Almanac News)

“It sheds new light on many aspects of early astronomy, from its highest achievements to its reception in poetry, art and myth.”

— Victor Gysembergh, Researcher (Almanac News)

“This material would have remained entirely inaccessible otherwise.”

— Victor Gysembergh, Researcher (Almanac News)

“The coordinates we are finding are incredibly accurate for something that is done with the naked eye, with no magnifying instruments, and the influence of that continued by later astronomers like Ptolemy, the Roman astronomer.”

— Victor Gysembergh, Researcher (Almanac News)

What’s next

Researchers have left SLAC and are now analyzing their findings. If the effort is successful, more pages of the Codex Climaci Rescriptus and other manuscripts may be scanned next. Scholars are hoping to publish a paper about the technology and their discoveries.

The takeaway

The recovery of Hipparchus' star catalog, one of the earliest comprehensive attempts to map the night sky, would provide invaluable insights into the origins of modern science and astronomy. The findings could also help settle longstanding debates about the relationship between the work of Hipparchus and Ptolemy, two of the most influential ancient astronomers.