Arthur B. C. Walker Jr., American physicist and academic (born 1936)

Arthur Bertram Cuthbert Walker Jr. was an American solar physicist and a pioneer of EUV/XUV optics. He developed normal incidence multilayer XUV telescopes to photograph the solar corona. Two of his sounding rocket payloads, the Stanford/MSFC Rocket Spectroheliograph Experiment and the Multi-Spectral Solar Telescope Array, recorded the first full-disk, high-resolution images of the Sun in XUV with conventional geometries of normal incidence optics. This technology is used in solar telescopes such as SOHO/EIT and TRACE, and in the fabrication of microchips via ultraviolet photolithography.

April 29 is the 119th day of the year in the Gregorian calendar; 246 days remain until the end of the year.