Section L NOTES AND REFERENCES: gives notes on the data and references for source material found in the almanac. Section K TABLES AND DATA: includes Julian dates, selected astronomical constants, relations between time scales, coordinates of the celestial pole, reduction of terrestrial coordinates, interpolations methods, vectors and matrices. Section J OBSERVATORIES: is a worldwide index of observatory names, locations, MPC codes, and instrumentation in alphabetical order and by country. Section H STARS AND STELLAR SYSTEMS: contains mean places for bright stars, double stars, UBVRI standards, ubvy and H beta standards, spectrophotometric standards, radial velocity standards, variable stars, exoplanet and host stars, bright galaxies, open clusters, globular clusters, ICRF2 radio source positions, radio flux calibrators, x-ray sources, quasars, pulsars, and gamma ray sources. Section G DWARF PLANETS AND SMALL SOLAR SYSTEM BODIES: includes positional and physical data on selected dwarf planets, positional information on bright minor planets and periodic comets. Section F NATURAL SATELLITES covers positional information on the satellites of Mars, Jupiter, Saturn (including the rings), Uranus, Neptune, and Pluto. Section E PLANETS: consist of detailed positional information on each of the major planets including osculating orbital elements, heliocentric ecliptic and geocentric equatorial coordinates, and physical ephemerides. Section D MOON: contains detailed positional information on the Moon including phases, mean elements of the orbit and rotation, lengths of mean months, ecliptic and equatorial coordinates, librations, and physical ephemerides.

Section C SUN covers detailed positional information on the Sun, including the ecliptic and equatorial coordinates, physical ephemerides, geocentric rectangular coordinates, times of transit, and the equation of time. Preprints of many of these data also appear in Astronomical Phenomena. Section B TIME-SCALES AND COORDINATE SYSTEMS: contains calendar information, relationships between time scales, universal and sidereal times, Earth rotation angle, definitions of the various celestial coordinate systems, frame bias, precession, nutation, obliquity, intermediate system, the position and velocity of the Earth, and coordinates of Polaris. Preprints of many of these data appear in Astronomical Phenomena, another joint publication by USNO and HMNAO. Publication contents Section A PHENOMENA: includes information on the seasons, phases of the Moon, configurations of the planets, eclipses, transits of Mercury or Venus, sunrise/set, moonrise/set times, and times for twilight. In addition to ancillary information, the Astronomical Almanac Online extends the printed version by providing data best presented in machine-readable form. It is designed to broaden the scope of the publication, not duplicate the data. The Astronomical Almanac Online is a companion to the printed volume. It is available one year in advance of its date. The book also includes references to the material, explanations, and examples. The material appears in sections, each section addressing a specific astronomical category.

The almanac largely contains Solar System ephemeris and catalogs of selected stellar and extragalactic objects. It is considered a worldwide resource for fundamental astronomical data, often being the first publication to incorporate new International Astronomical Union resolutions.

The Astronomical Almanac is an almanac published by the United States Naval Observatory (USNO) and His Majesty's Nautical Almanac Office (HMNAO) it also includes data supplied by many scientists from around the world. Alexander's band, the dark region between the two bows of a double rainbow.Annual publication containing astronomical information, especially about the Solar System.A circumzenithal arc over Grand Forks, North Dakota The Belt of Venus over Paranal Observatory atop Cerro Paranal in the Atacama Desert, northern Chile Crepuscular rays at sunrise in Malibu, California

Names of astronomical phenomena