Visible Objects

Aciqra shows a large number of objects of many different types. Some, like galaxies, nebulae, clusters and stars are relatively fixed objects and show up in almost the same place in the sky for years. Others, like asteroids, comets and planets require computations to determine their location in the sky at any given moment.

Stars

Aciqra includes over 2.5 million stars from the Tycho-2 and Hipparcos star catalogs. These catalogs include information on object coordinates, brightness (magnitude), color, proper motion and (for the Hipparcos catlaog) distance. Though fixed in comparison to solar system objects, stars do move slightly year after year. Proper motion and distance are used to help compute a highly precise position and magnitude for the star thousands of the years from the present.

Deep Space Objects

Aciqra uses the NGC and IC catalogs to provide information on deep space objects. Because these objects tend to be far away, they will not appear to move very much, even over periods of several thousand years. As a result, only information on the present state of the objects are provided. Such information includes object type, position, size, brightness (magnitude), shape and orientation. Approximately 13,000 objects are included in this catalog.

Sun, Moon and Planets

The Sun, Moon and Planets move rapidly in the sky on a daily basis. As a result, their positions must be computed regularly to keep up with their changing positions. The positions of the Sun and Planets are computed with VSOP87 theory -- specifically, the VSOP87D solution. This solution accurately computes planetary positions to within a few arcseconds (1 arcsecond = 1/3600 degrees) of accuracy for millennia into the future and the past. The position of the Moon is determined with the ELP2000-82 theory which has similar accuracy.

Minor Planets

Asteroids, comets and Kuiper Belt objects, like planets, have a continuously changing position in the sky thanks to their orbits. Their positions are computed from a set of Keplerian orbital elements valid for a given epoch close to the present. Their orbits change rapidly from epoch to epoch due to the influence of planets' gravity. Positions, especially those of Near Earth Objects, may be significantly off just a few weeks from the target epoch. Only one set of elements for a single epoch are stored in the database supplied with Aciqra.

Natural Satellites

The E5 theory is being used to determine the positions of the Galilean moons of Jupiter. Though there is a more modern, L1 theory available, the accuracy of E5 should be sufficient with an error undetectable with all but the biggest ground based telescopes.