Calibration
Masters, then lights
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
Aligned, weighted, stacked
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
Solved offline, on your machine
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.
| Platform | Windows 10 / 11, 64-bit. 16 GB RAM is a sensible floor for full-frame stacks. No GPU required. |
|---|---|
| Reads | FITS, XISF. One-shot-colour raw frames are debayered from the BAYERPAT header. |
| Writes | FITS and XISF 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. |
| Post-processing | Background extraction, colour and photometric colour calibration, histogram transformation, curves, denoise, sharpen, saturation, SCNR, multiscale, PixelMath, star and range masks, morphology. |
| Network use | Update check, Gaia catalogue download, licence sign-in. 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. |