AkastroidWhat Akastroid does
Deep sky, planets and the Moon, from import to finished image, on Mac, Windows and Linux. Each item below says what it does and which step or program it takes the place of.
Free to try on your own data. Processing runs on your computer and needs no account.
What it replaces
The usual setup is DeepSkyStacker or Siril for deep sky, PIPP to prepare planetary video, AutoStakkert to stack it, RegiStax to sharpen it, GraXpert for gradients, StarNet for stars and Photoshop to finish. That is seven programs, several of them Windows-only, with an export between each.
Everything on this page is in one application, on macOS, Windows and Linux, under one licence. None of it is an add-on or a separate purchase, and none of it needs an internet connection. Some of those programs still do their one job better, and the article below says which.
Getting your data in
Akastroid opens what your camera wrote. There is no converting or exporting first.
FITS
The astronomy standard. Seestar, Dwarf, ZWO, ASIAIR, N.I.N.A., anything.
No conversion step before you can look at a night's work.
Smart telescopes by name
Seestar S30, S50 and the Pro models, DWARF 3, DWARF II and mini, Vaonis Vespera and Vespera II, Celestron Origin, Unistellar eVscope and eVscope 2. Thirteen instruments are recognised from the file header.
These write no focal length and no pixel size. Knowing the model supplies both, which is what makes plate solving, annotation and drizzle possible. An unrecognised model is named but contributes no numbers, because a guessed pixel scale solves to the wrong part of the sky.
XISF
What PixInsight writes. A WBPP run gives you a folder of these and nothing else. Akastroid opens them directly, compressed or not.
Almost nothing outside PixInsight reads these. Your WBPP output is not stranded in it.
Camera RAW
Seventeen formats: Canon CR2, CR3 and CRW, Nikon NEF and NRW, Sony ARW, SRF and SR2, Fujifilm RAF, Olympus ORF, Panasonic RW2, Pentax PEF, Adobe DNG, plus Hasselblad 3FR, Phase One IIQ and Leaf MOS.
A DSLR on a tripod is real data, and so is medium format. No TIFF export first and no demosaic settings to choose. Fujifilm X-Trans files are refused rather than debayered as though they were Bayer, which would invent a grid that looks like detail.
Planetary video
SER in every common color format, and AVI both uncompressed and MJPEG.
This is where PIPP normally goes in a planetary workflow. You do not need it here.
An existing deep-sky stack
A FITS, XISF or TIFF from a Seestar, Siril, DeepSkyStacker, ASTAP or PixInsight opens directly and Akastroid finishes it.
Useful for a stack you do not want to redo, or for trying Akastroid on data you already have. Planetary works the other way round: open the SER or AVI and Akastroid grades, aligns, stacks and sharpens the whole capture, because that is where a planet image is won or lost.
Calibration
Darks, flats and bias found from your folder layout and applied without being asked.
The step most beginners skip, apply in the wrong order, or quietly apply twice.
Your equipment, recognized
The telescope and camera are read from the file's own headers, with smart telescopes identified by name.
Pixel scale and focal length are known before you are asked for them, so plate solving and drizzle have what they need.
Deciding what is worth keeping
Every frame is measured before anything is stacked, and every rejection comes with a reason.
Star quality
Count, sharpness, roundness and how far each frame's stars have drifted from the session's own norm.
Judged against your session, not a fixed threshold. A mediocre night is not graded as a failure.
Sky quality
Background level, gradient strength, noise and signal-to-noise.
Tells you whether the drive to a dark site was worth it, in numbers.
Artifacts
Cloud, satellite and aircraft trails, lost focus and overexposure, each named.
You find out which frames were bad and why, instead of wondering why the stack is soft.
Optics or tracking
Elongated stars traced to the real cause by whether the elongation is in every frame or only some.
The most commonly misdiagnosed fault in the hobby, answered rather than guessed at.
Your call
Overrule any automatic decision with a click.
Every decision is shown, so you can change the ones you disagree with.
Guard rails on rejection
It will never throw away more than 40% of a night, never reject every frame, and never reject one without naming the fault. If the thresholds would leave nothing, the best half comes back.
Automatic grading should never quietly throw away a session. These limits stop it.
The processing log
Every decision written down with the number behind it, and a diagnostics report you can copy and send.
When something looks wrong you can see what happened, rather than starting again and hoping.
Building the image
The expensive, once-per-session work: alignment and integration.
Star alignment
Asterism matching, so frames that rotated between exposures still line up.
Field rotation from an alt-az mount, which is what most smart telescopes use, is handled.
Integration
Averaging, median, sigma clipping or winsorized clipping, chosen from how deep your stack is.
The method is picked from your frame count, and the log says why.
Drizzle
Reconstruct at higher resolution when your frames were dithered. Akastroid measures whether they were and says so.
Drizzle on undithered frames only softens the image, so it checks first.
Mosaics
Stacked deep-sky panels placed by their shared stars, level-matched at the seams and feathered together.
Wide targets without a wider telescope, and without hand-blending seams in Photoshop.
Natural color
A filter wheel's red, green and blue combined into true color, with hydrogen blended into the red where you shot it.
This is the default for an RGB set, so there is no setting to find.
Narrowband palettes
SHO (the Hubble palette), HOO and HSO, or any channel by hand with a strength for each.
This step usually means a second program.
Filters recognized
The filter is read from each file's header or name: Ha, OIII, SII, R, G, B, L and their various spellings, dual-band names included.
Your set usually lands in the right channels without any sorting.
Registered on stars
Filters shot on different nights are aligned on their stars first; different sizes are matched onto the largest.
This avoids color fringes from stacks that are a fraction of a pixel apart.
Dual-band color cameras
L-eXtreme, L-Enhance, ALP-T, NBZ and similar filters recognized, with star colors left alone instead of forced to white.
The usual cause of a muddy dual-band image is skipped.
Making it look right
Each step is set from measurements of your frame rather than from a preset.
Gradient removal
Light pollution, moon glow and vignetting modeled and removed while the sky keeps its level.
This is usually the largest visible change on a backyard image. The background is not subtracted to black.
Neutral sky
The green and magenta tints a stretch leaves in the background, measured from the sky's own most common value in each channel and shifted out.
A stretch carries color faithfully, which is right for the object and wrong for the sky. Two per cent is enough to read as a cast across a large area. It shifts rather than scales, so everything brighter than the sky is left as it was and the nebula keeps its color.
Photometric color
Your field matched against 1.48 million cataloged stars with measured colors, and the white balance fitted to what those stars are.
Color set by measurement, instead of by temperature and tint sliders.
Deconvolution
The blur is measured from the stars in your own stack and undone, with a guard that declines to run when the data cannot take it.
The sharpening is based on what your optics and the seeing did, instead of a radius you picked. It is included, not a separate purchase.
Adaptive stretch
The curve is solved from your histogram, not guessed, with bright cores protected so a nebula core stays a core.
This turns a flat gray stack into a picture. It is also the step that takes longest to learn by hand.
Tighter stars
Stars pulled in with the sharpening rather than smeared by the stretch, in four steps you control.
Soft, bloated stars are usually a stretch artifact, so this works on the stretch instead of shrinking stars afterwards.
Star reduction
Each star's own profile is drawn smaller in place, up to a third off its width at the same peak. The nebula underneath and neighbouring stars are left where they were.
Stars read smaller but not dimmer, and crowded fields get no ghosts between stars. The shrink only touches light that is symmetric about one star, and it is measured on real stacks before every release.
Star colour
A slider that saturates only the stars, cores and halos, clamped so no channel reaches white.
Blue stars get bluer and orange ones warmer while the sky and the nebula keep their colour. Measured: star chroma up more than 1.3x at the 2x setting, pixels away from any star unchanged.
Star halos
Every halo takes its own core's colour, and no star is ever green: green is capped at the average of red and blue on the star's light above the sky.
This removes the red rim a lens leaves on mid-brightness stars and the mint halo around bright ones, without desaturating the whole image.
Colour cast
The cast control at the top of the adjust panel, with a readout of how much green or magenta is in your sky before you move anything.
A colour cast is usually the first thing you check after a stack, so the control is at the top.
Denoise and detail
Multiscale, applied hardest where the signal is weakest and held back over real structure.
Noise reduction that leaves the faint dust in place.
Planets and the Moon
Lucky imaging from SER and AVI captures, in the same application as deep sky.
Frame grading
Every frame in the capture scored for sharpness, with a graph of how the seeing changed.
This is AutoStakkert's grading step. AutoStakkert does not run on macOS.
Compared with AutoStakkert
Stacked against AutoStakkert on eight captures, unsharpened, at matched physical frequencies and matched noise: level on detail, and quieter on every one.
The comparison page lists where Akastroid loses too. AutoStakkert stops at the stack, and the sharpening after it is usually RegiStax, unmaintained since 2011. Both are Windows-only.
Multi-point alignment
The disc tracked in pieces, so the atmosphere's local warping comes out.
This is most of the difference between a soft planetary stack and a sharp one.
Finer-grid integration
An undersampled planet is integrated onto a finer grid, recovering detail below the original pixel scale.
Helps most on small discs such as Mars, Uranus and Neptune.
Dispersion and wavelets
Red and blue realigned to green, then six sharpening layers you control directly.
Replaces RegiStax, which has been unmaintained since 2011 and is Windows-only.
Rotation animation
The capture stacked in time slices, so a planet that turned during the session is shown turning, written as a GIF or an AVI.
Every slice shares one reference and one sharpening, so the result rotates without flicker.
Lunar close-ups
When the Moon fills the frame or runs off its edge, frames are lined up by matching the whole surface rather than by hunting for a disc that is not there.
A drifting close-up stacks without streaks, and there are no alignment points to place by hand.
Every planet
Mercury through Neptune, the Moon and Venus in ultraviolet, color or mono, SER or AVI.
The same workflow for each of them.
Frame quality graph
Every frame ranked sharpest to softest on one curve, with a handle you drag to choose how many go into the stack.
You can see where the good frames end instead of guessing a percentage.
Plate solving
The field matched against the sky from the frames' own pointing information.
Tells you where the telescope was pointing, to the arcminute.
Annotation
Galaxies, nebulae, clusters and bright stars named in one click. Galaxies are drawn as ellipses at their real angle, and crowded fields stay readable.
Faint objects in the field get labelled too, which is often how you find out they are there.
Your catalogues
Messier, NGC, IC and everything else as separate switches, and stars and the coordinate grid on their own.
The Leo Triplet can be labelled as three galaxies without thirty IC entries around them.
Burned into the export
Apply the overlay and it is written into the file, with an undo.
You get a labeled image file to post, not a screenshot.
Finishing and sharing
Formats and sizes for whatever you do next.
Three styles
Natural, Enhanced and Dramatic, all rendered from the same data. Switching is instant.
Switching style does not redo the stack.
Color tools
Histogram, curves, hue-selective saturation, green-cast removal, temperature and tint, with a live preview.
The manual controls are there when you disagree with the automatic ones.
Crop, turn and mirror
Quarter-turns, a mirror on either axis, and a crop you drag on the picture itself, for planets and the Moon as well as deep sky.
Put north where you want it, and crop a small disc on a large sensor before export.
Maximum quality
A 16-bit TIFF at full size with lossless compression, plus presets for print, desktop wallpaper at up to 3840 px, and JPEG sized for social media.
The full-quality file is the default.
Custom watermark
Your name or credit, any corner, sized and faded to taste, previewed before export.
Off by default.
Keeps the data
A FITS master holding the float data with a record of what was done to it, and the unprocessed stack as a 32-bit float TIFF.
Another program can pick up the stack, and Akastroid reopens it as a stack rather than as a picture.
Exports that are checked
A written TIFF is read back and measured against the size it should be. A short file is deleted and reported ("only 16 MB of the 217 MB it needs, usually a full disk") rather than left looking finished.
A truncated file that reports success usually goes unnoticed for months. This one is reported at the time.
Gift artwork
A print-ready poster built around your real telescope image for a birthday, anniversary, wedding or graduation, with the photograph and the decoration clearly labeled as different things.
The photograph is yours, and the poster says which parts are decoration.
Runs entirely offline
Every stage of processing happens on your own machine. Your images are never uploaded, and there is no account to make.
It works at a dark site with no signal. The app checks for updates and reports once per version that it opened. One setting turns both off, and both are described in the privacy policy.
Free to try
A free tier on your own data rather than a countdown, then one payment, or $11.99 a month if you prefer.
You can check it on your own files before paying.
36 languages
English, Deutsch, Français, Español, Italiano, Português, 日本語, 简体中文, Русский, 한국어, العربية and 25 more. Switch at any time from the top bar.
The processing log and explanations are translated too.
Mac, Windows and Linux
A native application on Apple silicon, Intel Macs, Windows and Linux (beta). No Wine or virtual machine.
Most planetary tools are Windows-only.
Updates when you want them
New versions are offered, with the changes listed, and installed when you say so.
Nothing changes in the middle of a session.
What Akastroid will not do
There is no neural network in Akastroid and no model file in the download. Nothing paints in nebula structure or invents detail. It measures frame quality, noise and artifacts, sets parameters from those measurements, and then combines the pixels you photographed. The processing log records what was done. If a competition asks whether AI was used, the answer for Akastroid is no.
Download for Mac, Windows or Linux
Deep sky and planetary under one licence.