The best astrophotography software,
and which one to open first.

The short answer

• Deep sky, free, any OS: Siril.
• Deep sky, free, Windows, simplest possible: DeepSkyStacker.
• Planets and the Moon: AutoStakkert! to stack, RegiStax to sharpen.
• Nightscapes on a tripod: Sequator.
• Both kinds of target without assembling a workflow: Akastroid.
• No ceiling, and a year to spend on it: PixInsight.

Calibration, registration, stacking and a full set of post-processing tools, with a scripting language that can run a whole session unattended.

Install it if: The best free starting point for deep sky, on any operating system, if you are willing to learn the order the steps go in.

The catch: It does what you tell it and nothing you did not. The scripts in the manual assume you already know which one matches your data.

Loads lights, darks, flats and bias frames and produces a stacked master. That is its entire scope.

Install it if: A Windows beginner who wants one job done and is happy to finish the image somewhere else.

The catch: Windows only, development is slow, and it stops at the stack - the flat grey result it hands back still needs a second program.

The standard for planetary and lunar stacking: grades every frame of a video, keeps the sharpest, and aligns on a grid of points across the disc.

Install it if: Anyone stacking planetary or lunar video. It is free and it is very good at this one thing.

The catch: Stacking only - the result is deliberately soft and expects RegiStax or equivalent afterwards. No deep sky, and no macOS build.

Wavelet sharpening. Six sliders that pull detail out of a planetary stack at six different scales.

Install it if: The second half of a planetary workflow, after AutoStakkert! has produced the stack.

The catch: Unmaintained since 2011, and the sliders have no defaults worth starting from - the result is whatever you dial in, including badly over-sharpened.

Gradient removal, plus optional denoising. Not a stacker - it fixes one specific problem in an image you already have.

Install it if: Anyone whose stacked image has an uneven background from light pollution or moonlight.

The catch: One step of a workflow, so it is an addition to your shortlist rather than an answer to it.

Deep sky and planetary in one program: it measures your frames, decides the calibration, stacking, gradient, colour and stretch for itself, and shows you the numbers behind each choice.

Install it if: Someone who wants a finished image from a night's data without first learning which of five programs to open in which order - and who wants to see what it did rather than trust a black box.

The catch: Opinionated by design. If you want to drive every decision yourself, PixInsight gives you more control and Siril is free.

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Stacks wide-field nightscapes - Milky Way over a landscape - keeping the fixed foreground sharp while the stars are aligned.

Install it if: Camera-and-tripod nightscapes, which the telescope-oriented stackers handle badly.

The catch: Windows only, and it is for landscape astrophotography specifically - not much use on a telescope target.

The most capable image-processing platform in astrophotography, and the one nearly every published image passes through eventually.

Install it if: Someone past their first year who has hit a ceiling and wants no ceiling at all.

The catch: Months to learn, and the interface assumes you already understand the mathematics. It is not a first program, and its own community says so.

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What is the best astrophotography software for beginners?

For deep sky on any operating system, Siril - it is free, actively developed and covers the whole workflow. On Windows, DeepSkyStacker is simpler but stops at the stack. For planets and the Moon, AutoStakkert! followed by RegiStax. If you would rather not assemble a workflow out of three programs, Akastroid covers deep sky and planetary in one and is free to try.

Is there free astrophotography software that is actually good?

Yes. Siril, DeepSkyStacker, AutoStakkert!, RegiStax and GraXpert are all free, and the first four are what most of the images you have seen were made with. Cost is not the thing separating them from paid software - the difference is how much of the sequence you have to know before you start.

Do I need different software for planets and deep sky?

Traditionally yes, because the two need opposite things: deep sky stacks long exposures to beat noise, while planetary grades thousands of short video frames and keeps only the sharpest moments of seeing. That is why most people run DeepSkyStacker or Siril for one and AutoStakkert! plus RegiStax for the other. Akastroid was built to do both, detecting which kind of data you loaded.

What is the best astrophotography software for Mac?

Siril, PixInsight, GraXpert and Akastroid all have native macOS builds. DeepSkyStacker, AutoStakkert!, RegiStax and Sequator are Windows-only - AutoStakkert! and RegiStax can be coaxed into running under Wine, but that is an extra problem to own rather than a solution.

How much should I spend on astrophotography software?

Nothing, until free software has stopped being the limit. Almost everybody who buys a licence early finds the bottleneck was their focus, their guiding or their light pollution, not the program. Spend on the data first.