40 CCDs of the MegaCam wide-field camera: design and first tests of the front-end electronics

40 CCDs of the MegaCam wide-field camera: procurement, testing, and first laboratory results

40 Harmonia CCD Spectrum

40 New Southern Red Variables

40 previously unreported variable stars in the OGLE-II database

40 Signs of Supermassive Black Hole Binaries

40 years of whistlers

40, 000 years of extinctions on the ``planet of doom''

40-70 day meridional propagation of global circulation anomalies

400 GeV Gamma Rays From AE Aquarll

400 Gev gamma rays from the X-ray pulsar 1E2259+586

400 Jahre Mathematik und Astronomie an der Universitat Wurzburg: Alma Julia Herbipolensis 1582-1982 (400 Years Mathematics and Astronomy at the Wurzburg University: Alma Julia Herbipolensis 1582-1982)

400 years of large fluence solar proton events

400 years of Uranometria.

400-kW Harmonic Filter

4000 years of climate change in Northern Spain from speleothem records

4001 Ptolemaeus CCD Spectrum

400mm aperture lidar system and its applications

400th Anniversary of Johannes Kepler's Birth: AAAS Symposia, Annual Meeting: Philadelphia, 27 December

4015 Wilson-Harrington, 2201 Oljato, and 3200 Phaethon: Search for CN Emission