Calibration
Frames are grouped by filter, binning and exposure from their FITS headers. Master bias, dark and flat are built with median or sigma-clipped mean stacking, with dark-flat pairing where you shot them.
Each light is then bias-subtracted, dark-subtracted with exposure scaling, flat-divided, cosmetically corrected and given a pedestal. One-shot-colour sensors are handled from the BAYERPAT header: defect correction is CFA-aware, so a hot pixel is replaced from same-colour neighbours rather than the wrong ones.
Registration and integration
Auto Integrate Script (AIS) runs the whole of it in one pass — calibration, alignment, integration and auto-crop — from folders of raw frames to a finished stack, with every per-frame measurement written out beside it.
Star-based alignment resamples with Lanczos-3 and reports the residual for every frame. Drizzle integration is available when your sampling supports it. Colour frames are warped with a single transform across all three channels.
Integration weights frames on measured quality, normalizes background and scale locally, and rejects outliers through a single shared engine — Winsorized sigma, percentile, linear-fit or ESD. A guard watches the finished stack and warns in the log when it sees the dark-pixel signature of a feathering or rejection fault.
Plate solving
The solver is built in. It detects stars, selects anchors, cone-queries a local Gaia catalogue and fits a TAN or SIP solution with proper-motion correction — then writes the WCS into the FITS header.
There is no astrometry.net call and no solve-field subprocess. Once the catalogue is on disk, solving needs no network at all. A solution is only accepted after an independent cross-match check; when that check cannot be made, it fails rather than guessing.
Scripts
These run across folders and nights, not one open image — grouping frames, building masters, stacking, indexing an archive. This is most of what the app is for; the processes below are what you reach for afterwards, on the result.
A whole night, one pass
Folders of raw frames to a finished stack in one pass: grouping by filter, binning and exposure, masters, calibration, star alignment, weighted integration with rejection, and auto-crop. Every per-frame measurement it used is written out beside the result.
An archive, read-only
Indexes an archive from FITS headers — nothing is moved, renamed or modified, so it is safe to point at twenty years of data. Then it answers questions across folders: which darks sit within a temperature and exposure tolerance of this light, what is duplicated, which frames disagree with the folder they are in. Filing is a separate step: it builds the whole plan first, writes it to a file, and the last run can be undone.
At the telescope
Stack at the telescope while the session is still running, with the same per-frame quality control the full path uses. What builds up on screen is the same measured stack you would get afterwards, not a quick preview thrown away at the end.
Data Library, live
The same archive, two views from the app. Hover the panel — or use the buttons — to move between what the Library found and the plan it wrote. Nothing on disk changes until you apply it.
move_plan.json — and the last run can be undone.Processes
These run on an open image, not the whole session. Each one folds open to its real panel from the app — the controls are the app’s, shown as they appear; what you cannot do here is drag the sliders, because that is the Qt engine, not the page.
Photon-transfer measurement of sensor gain in e-/ADU and read noise in electrons, from pairs of frames rather than from the datasheet — the EGAIN written into a header is often wrong, and every noise figure downstream inherits that error.
Tilt, coma and tracking error read from star shapes across the field, so a soft corner is attributed rather than guessed at.
Per-channel readouts for the whole image or a selection — mean, median, deviation, and the histogram they came from.
One-shot-colour raw frames to RGB, driven by the BAYERPAT header. Mono frames are untouched by it.
Crop, rotate and flip, with resampling.
The auto-stretch the viewer uses to make linear data visible, applied to the pixels when you want it applied.
Shadows, midtones and highlights against a live histogram, with a preview before it is applied.
Curve editing on luminance and on individual channels.
A stretch with an explicit control over where contrast is spent, for data a midtone transfer handles badly.
Direct tonal adjustment on an already-stretched image.
Build RGB or LRGB from separate channels, including narrowband palettes.
Background neutralisation and white balance from selected regions.
White balance from Gaia photometry: the field is solved, detected stars are cross-matched to the catalogue, and the per-channel scales come from a regression of measured against predicted flux.
The same idea with the filter response taken into account rather than a broadband approximation.
Per-hue mixing, for shifting one colour without dragging the rest with it — and saturation by hue in the same place, so a nebula can be lifted without turning the stars into beads.
Removes the green cast narrowband and OSC data tend to carry.
Classical filtering, or the AstrylAI model. Both run locally; the model uses a compatible GPU when there is one.
Regularised Richardson-Lucy with a multiscale regulariser and deringing, blended through a star mask so the sky keeps its own grain instead of mottling. A model-based engine is in the build but not finished, and is not what this row describes.
Unsharp-mask style sharpening with edge protection.
Work on one spatial scale at a time — the layer where faint structure and noise are separable.
Splits stars from the rest, so the two can be stretched and sharpened on their own terms and recombined.
A mask from detected stars, with size and softness under control.
A mask from a brightness range, for confining any process to it.
Arithmetic across open images with named variables and the usual functions.
A surface fitted to sampled points and subtracted or divided out. Samples can be generated on a grid or placed by hand, and stars are rejected from them.
| Platform | Windows 10 and 11, 64-bit. One installer, no runtime to fetch separately. |
|---|---|
| Reads | FITS, XISF. One-shot-colour raw frames are debayered from the BAYERPAT header. |
| Writes | FITS as the working format. Export produces TIFF, PNG or JPEG with the displayed stretch baked into the pixels. |
| Calibration | Master bias / dark / flat, dark-flat pairing, exposure-scaled dark subtraction, CFA-aware cosmetic correction, pedestal. |
| Registration | Star-based alignment, Lanczos-3 resampling, optional drizzle, per-frame residuals. |
| Rejection | Sigma clip, percentile, Winsorized sigma, linear fit, ESD — one shared implementation for master frames and light integration alike. |
| Plate solving | Internal, offline, against a local Gaia catalogue. WCS written to the header. |
| Running it | |
| Memory | 16 GB is a sensible floor for full-frame stacks. Master frames switch to a chunked accumulation above about 4 GB, and the final light combine reads from disk in chunks, but each filter's lights are held in memory while they are measured and aligned, so very large sessions need more. |
| Working drive | Keep the session on a fast internal drive. Registration writes an aligned copy of every frame: a 104-frame 15-megapixel session is about 9 GB of intermediates, and reading them back from an external disk dominates the run. |
| GPU | Not required. The two AstrylAI models use a compatible GPU through DirectML when one is present and the CPU when it is not; nothing else in the pipeline needs one. |
| Alignment speed | The Lanczos-3 resampler is JIT-compiled when numba is available — measured at 1.6 s against 45 s per 15-megapixel frame without it. It is optional, and the pipeline is correct either way. |
| Network use | Licence sign-in, price list and release notes, Gaia catalogue download and target lookup when asked, run reports (a release build asks first; the beta sends them by default and says so). No image data is transmitted. |
| Logs | Written locally to %APPDATA%\AstrylStudio\logs\. Help ▸ Export Diagnostics bundles them for a bug report; the bundle deliberately excludes your session and licence files. |