Flat)¶

Master frames (bias_master, dark_master, flat_master) can be used directly
Directory-based masters (bias_dir, darks_dir, flats_dir) can be built automatically
When use_bias: true and use_dark: true, raw darks are bias-corrected internally unless dark_already_bias_corrected: true is set
dark_auto_select: true matches darks by exposure time (±5%)

External Sources (PCC and Astrometry)¶

For optional color calibration and astrometric solving, the pipeline can use external data/tools:

Siril Gaia DR3 XP sampled catalog (for PCC)¶

Can be reused if already downloaded by Siril.
Typical local path: ~/.local/share/siril/siril_cat1_healpix8_xpsamp/
Upstream source (catalog release): https://zenodo.org/records/14738271
Download via GUI3: Tab Tools → PCC → Download Missing automatically downloads missing catalog chunks (~2 GB, 48 chunks).

ASTAP (for astrometry / WCS plate solving)¶

Requires ASTAP plus a star database (e.g., D50 for deep-sky use).
Official site/downloads: https://www.hnsky.org/astap.htm
Download via GUI3: Tab Tools → Astrometry → Install CLI and Download Catalog download ASTAP binary and star database directly.

If these resources are not installed, core reconstruction still works, but ASTROMETRY/PCC phases may be skipped or fail depending on configuration. BGE (Background Gradient Extraction) works independently of external catalogs.