It aligns and stacks images. Tutorial videos: https://youtu.be/yMwrJgzJiAo https://youtu.be/GY5q7bp8r88 Note: This app is designed to capture dark night sky object. In presence of Sunlight or Indoor light, the screen will be washed out. Requirement: This app requires Goto (computerized) telescope that tracks the sky object to prevent star trail. However, you can still use it on a static camera tripod to capture Milky Way for exposure more than 10 minutes.