A team of astronomers has, for the first time, observed the faint companion star orbiting the millisecond pulsar PSR B0655+64 in the GALEX Near‑UltraViolet band. The new image gives a magnitude of 24.06 ± 0.26, confirming that the secondary star can be seen in ultraviolet light.

To find this companion the researchers cross‑matched hundreds of catalogues from optical, infrared and ultraviolet surveys. They used an association radius equal to three times the nominal survey astrometric uncertainty and then calculated the probability that each match could occur by chance. The resulting chance–coincidence probabilities were as low as about 10‑⁴–10‑³, which makes the detection statistically robust even in crowded fields.

This discovery adds a new data point to the spectral energy distribution of the system, helping to refine models of the companion’s temperature and composition. Earlier work had reported only infrared and optical detections, so the ultraviolet measurement completes the picture from near‑UV to mid‑IR.

The study also examined time‑series data from the Catalina survey for another millisecond‑binary, PSR J1023+0038. Its V‑band light curve shows a clear 0.4–0.7 mag modulation over the binary’s orbital period, corroborating earlier multi‑band observations of flux variability.

While the ultraviolet detection is reliable, the authors note that their method depends on precise astrometric uncertainties and that the faintness of the companion limits further spectroscopic analysis with current instruments.