RegiStax is a free image processing software for amateur astrophotographers, released as freeware, which runs under Windows. A compatible version for Mac OS is also available as a emu file (see Download below)
Its purpose is to produce enhanced images of astronomic observations through combining consecutive photographs (an image “stack”) of the same scene that were taken over a short period of time. For example, many frames can be obtained from a video and then stacked in Registax. The process relies on the subject (for example a planet or the Moon) being unchanged between photographs, so that any differences can be assumed to be random noise or atmospheric interference.
The stack of images can be in the form of individual consecutive shots or from frames of a movie camera trained on the scene.
As the official website of Registax is having problems at the moment (hacking issue i think), i uploaded Registax and its update to my website. Please find bellow the new links :
IMPORTANT : Please note that you should install Registax 6.1 before installing the Update file.