The star maps are in OpenEXR's half-float format, which provides higher dynamic range in a linear colorspace while easily accommodating very large files. The boundary, figure, and grid images are conventional grayscale TIFF files. The new images use the transformation described in the Hipparcos and Gaia documentation. ![]() The original images used ICRF/J2000 coordinates in a galactic coordinate transformation meant for B1950. Update: The galactic images were replaced on January 4, 2021. It also works as a standalone image showing the edge-on view of our home galaxy, from the inside. The galactic coordinate mapping is probably better for 2D animation and compositing. The celestial coordinate mapping will be the more useful one for 3D animation, since camera rotations in the software will correspond in a straightforward way to the right ascension and declination in astronomy references. The distortion of the stars in those parts of the map is just an effect of the projection. The oval shapes near the top and bottom of the star maps are not galaxies. They are designed for spherical mapping in animation software. The maps are presented in plate carrée projections using either celestial (ICRF/J2000 geocentric right ascension and declination) or galactic coordinates. The constellation figures also come from the IAU, although they're not official. The constellation boundaries are those established by the International Astronomical Union in 1930. It is contrasted with oblique ascension, the point on the celestial equator which rises with a celestial object as seen from almost anywhere else on Earth, where the celestial equator intersects the horizon at an oblique angle.This set of star maps was created by plotting the position, brightness, and color of 1.7 billion stars from the Hipparcos-2, Tycho-2, and Gaia Data Release 2 star catalogs, with help from the Yale Bright Star Catalog, UCAC3, and the XHIP Hipparcos cross-reference. An old term, right ascension refers to the ascension, or the point on the celestial equator which rises with any celestial object, as seen from the Earth's equator, where the celestial equator intersects the horizon at a right angle. Right ascension is measured eastward along the celestial equator from the primary direction. The primary direction of the system is the vernal equinox, the ascending node of the ecliptic on the celestial equator. Right ascension and declination as seen on the inside of the celestial sphere. When combined with declination, these astronomical coordinates specify the direction of a point on the celestial sphere in the equatorial coordinate system. Right ascension is the angular distance measured eastward along the celestial equator from the vernal equinox to the hour circle of the point in question. ![]() É contrastada com a ascensão oblíqua, o ponto no equador celestial que se eleva com um objeto celestial visto de quase qualquer outro lugar na Terra, onde o equador celestial cruza o horizonte em um ângulo oblíquo. Um termo antigo, ascensão direta refere-se à ascensão, ou ao ponto no equador celestial que se eleva com qualquer objeto celestial, visto do equador da Terra, onde o equador celestial cruza o horizonte em um ângulo reto. A ascensão direta é medida para o leste ao longo do equador celestial da direção primária. ![]() A direção principal do sistema é o equinócio vernal, o nó ascendente da eclíptica no equador celestial. Ascensão e declinação direitas como observadas no interior da esfera celestial. Quando combinados com declinação, essas coordenadas astronômicas especificam a direção de um ponto na esfera celestial no sistema de coordenadas equatoriais. Right ascension A ascensão direta é a distância angular medida a leste ao longo do equador celestial do equinócio vernal ao círculo de horas do ponto em questão.
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