Tools Astrocalculator Apparent Coordinates module The Apparent Coordinates calculator module Apparent Coordinates The Apparent Coordinates module converts the catalog coordinates of a point in the sky to its apparent coordinates for any date. The coordinates of objects in the sky are not fixed, because of precession, nutation and aberration. This module takes these effects into account. To use the module, first enter the desired target date and time in the Target Time/Date section. Then, enter the catalog coordinates in the Catalog Coordinates section. You can also specify the catalog's epoch here (usually 2000.0 for modern object catalogs). Finally, press the Compute button, and the object's coordinates for the target date will be displayed in the Apparent Coordinates section.