Restrictions and Requirements

All input images must be either RAW files from supported cameras, RGB TIFF files or (not recommended) JPEG files. TIFF files should be 16-bit with a wide gamut profile such as ProPhoto RGB, ROMM RGB or Adobe RGB. Images must be RGB (not grayscale). FITS files are not supported. Astronomical cameras with monochrome sensors that use color filters to produce a set of images that must be assembled into an RGB image are not supported.

The camera is assumed to track the main objects of interest (stars, moon, …) on an equatorial mount. Some small error in the tracking is allowed. Small errors in tracking may improve noise reduction. Alt-azimuth mounts are not suitable for use with Starry Sky Stacker because the stars appear to rotate within the frame both during and between exposures.

There should be no foreground. Any foreground will get blurred and might interfere with alignment.

The pictures should be mostly stars. If a large part of the image is very bright and the rest is dark (e.g., a bright moon on a black background) or there is a large area that lacks detail (e.g., a large dark cloud) the images may fail to align.

All light frames should have identical exposure settings (duration, aperture, ISO, focus).

macOS 10.11 or newer. There is no version for Windows or Linux.