Starry Sky Stacker reduces noise in pictures of the night sky that are captured as a sequence of exposures using an equatorial mount or some other mechanism that ensures that stars move very little either during or between exposures. Starry Sky Stacker aligns the images to compensate for errors in tracking,
assigns a quality estimate to each image, allows the user to select images based on the quality estimate, and finds the median. The resulting image has much less noise than any of the original images.

What’s New

Version 1.3.1

Fixed an error that would cause a failure to align under certain combinations of lens focal length, sensor physical size and sensor pixel count. Failure was very likely with a telescope and a crop frame sensor.

Added a check box at the bottom of the open panel that overrides any lens information in the EXIF data. This is useful to telescope users in two cases: you are using a smart phone or some other camera that always puts a focal length in the EXIF data with a telescope, you always use a telescope and are tired of typing "1000" into the pop-up dialog that asks for lens focal length.

Ratings and Reviews

TomS51 ,

Happy with program

Have used this on three deep sky images and have been very happy with the result. It greatly reduced the noise and improved the quality of the images, which were based on sets of 12 to 40 images. The automatic image quality rating did not work so well in the 40-image case. Some of the images that were classified as poor were not so bad and some that were classified as good were not so good. You definitely want to check the image quality manually and not just rely on the program. Its easy to manually examine the images and eliminate ones that are not good. I found that the mean worked slightly better than the median in one case.

Calvin Knight ,

Updated Review

I purchased this program a few years back and had unfavorable results and gave a "less than stellar" review. Recently I returned to it, spent quite a bit of time reading the updated instructions and noticed some version improvements. After spending quite a bit of time with it and some other imaging software I got results better than I had expected. My final images seemed like they still have quite a bit of noise, but after running through other software the final image was stunning.

Developer Response ,

Could you contact me directly please? Launch Starry Sky Stacker and in the menu bar select "Help->Contact Developer". Starry Sky Stacker is working well for many people. I would like to find out why it is not working for you.

lightyearhour ,

Below average

For some reason, this program doesn't let me stack darks or flats. All it says is that my photos are not the same color settings when all my photos are clearly the same sRGBs, and have not changed that setting at all since starting Astro. Not sure if it's a bug but it should be fixed, since darks and bias frames are best practices for AP.

Developer Response ,

I think I know the reason that SSS is not allowing your darks and flats, but first, if you have a problem, the best thing to do is click on "Help" in the menu bar. There is a menu item there to send me mail. There is also a link to send me mail on every page of the online documentation. Most messages are replied to in under 24 hours. If you post a review, it will be months before I read it. 

The reason you are having a problem is almost certainly that you have two (or more) sRGB profiles with very similar, or possibly identical, names. So, your darks and flats probably do have different profiles like SSS says. The best solution is to switch to either the ProPhoto RGB profile or Adobe RGB profile. sRGB has a pretty restrictive gamut and you probably should not use it. I have seen several cases where users have somehow ended up with two or more sRGB profiles. I have never seen more than one instance of ProPhoto RGB or Adobe RGB on a user's computer. If you really must use an sRGB profile, you should be careful when working with SSS to always use the same sRGB profile.


Ralph Hill
9.6 MB

OS X 10.10 or later, 64-bit processor



Age Rating


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.