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The 26 inch (66 cm) aperture telescope, with which Asaph Hall discovered the moons of Mars in 1877; the telescope is shown at its modern Northwest DC location.. President John Quincy Adams, who in 1825 signed the bill for the creation of a national observatory just before leaving presidential office, had intended for it to be called the National Observatory.
[1] [2] In the United States, a nautical almanac has been published annually by the US Naval Observatory since 1852. [2] It was originally titled American Ephemeris and Nautical Almanac. Since 1958, the USNO and HMNAO have jointly published a unified nautical almanac, The Astronomical Almanac for use by the navies of both countries. [2]
Two sample pages of the 2002 Nautical Almanac. The Nautical Almanac has been the familiar name for a series of official British almanacs published under various titles since the first issue of The Nautical Almanac and Astronomical Ephemeris, for 1767: [1] this was the first nautical almanac to contain data dedicated to the convenient determination of longitude at sea.
Twilight occurs according to the solar elevation angle θ s, which is the position of the geometric center of the Sun relative to the horizon. There are three established and widely accepted subcategories of twilight: civil twilight (nearest the horizon), nautical twilight, and astronomical twilight (farthest from the horizon).
The Astronomical Almanac [1] is an almanac published by the United Kingdom Hydrographic Office; it also includes data supplied by many scientists from around the world.On page vii, the listed major contributors to its various Sections are: H.M Nautical Almanac Office, United Kingdom Hydrographic Office; the Nautical Almanac Office, United States Naval Observatory; the Jet Propulsion Laboratory ...
The American Ephemeris and Nautical Almanac was published for the years 1855 to 1980, containing information necessary for astronomers, surveyors, and navigators. It was based on the original British publication, The Nautical Almanac and Astronomical Ephemeris, with which it merged to form The Astronomical Almanac, published from the year 1981 to the present.
From 1865 to 1884, the Bureau was responsible for the Office of Detail, which handled the assignment and detailing of naval officers. That Office had been established in March 1861, just prior to the outbreak of the Civil War, in the Office of the Secretary of the Navy. The Office of Detail reverted to the Secretary's office on October 1, 1884 ...
Twilight, the period in the morning during which the sky is brightening, but the Sun is not yet visible. The beginning of morning twilight is called astronomical dawn. The period after the Sun rises during which striking colors and atmospheric effects are still seen. [5] Civil twilight being the brightest, while astronomical twilight being the ...