StarCalc is a professional astronomy, planetarium, and star mapping application. StarCalc lets you display star positions during any time of a given day and observed from any geographic location on Earth. Star positions can be viewed and presented as semi-spherical images of the whole sky or any user-defined sub-area. These images can be rotated, zoomed at different scales, screen-captured, and printed. The program supports plug-ins, and its efficient algorithms enable it to calculate a sky image in a fraction of a second.