ASTAP (Astro Stacking and Astrometric Plate solver) is a free and open-source software program designed for astronomical image processing and analysis. It was developed by Han Kleijn in the Netherlands and is available for Windows and Linux operating systems.
ASTAP can be used for stacking and aligning multiple astronomical images, however its primary purpose in our workflow is as a powerful astrometric plate solver service running in the background. It’s purpose is to examine an image taken of the sky and return exact coordinates. This can then be used to correct alignment of the main scope so that’s it’s pointing to the correct area of the sky.
One of the unique features of ASTAP is its ability to use multiple star catalogs, including the popular USNO, UCAC, and GSC catalogs, as well as its own built-in catalog. This allows users to achieve high levels of accuracy and precision when aligning images, even in crowded fields with many stars and other objects.