skycam_utils is an MMT-Observatory utility package for analyzing all-sky
camera images. It supports three distinct camera systems whose data formats and
calibration assets differ:
- Stellacam — the original narrow-dynamic-range all-sky camera and the main target of the Stellacam pipeline. Decommissioned in 2022; the pipeline is frozen and maintained only for legacy data access.
- ASI (ASI1600) — a one-off test camera, solved by running
astrometry.netsolve-fieldon a central cutout. Also frozen, for legacy data access. - Alcor OMEA 8C — an RGB CMOS all-sky camera in continuous operation since August 2024. Its geometry and photometry pipeline is the most fully developed part of the package and the focus of active development.
The Alcor OMEA pipeline is built around a single principle: the WCS is the one source of truth for geometry and orientation. When a raw frame is loaded, an ARC-projection world coordinate system is attached that maps every pixel to an (azimuth, altitude) on the sky, encoding the zenith offset, camera rotation, lens distortion, sensor tilt, and optical-axis tilt. Everything downstream — star photometry, the horizon mask, and sky-brightness maps — reads geometry from that WCS rather than re-deriving it.
Full documentation is at skycam-utilities.readthedocs.io, including installation, WCS calibration, photometry, the bad-pixel and horizon masks, sky-brightness mapping, and the full API reference.
skycam_utils is not published on PyPI, and its version is generated by
setuptools_scm at build time, so install from a git checkout:
git clone https://github.com/tepickering/skycam-utils.git
cd skycam-utils
pip install -e ".[test]"See the installation guide
for optional dependency groups and the external tools (astrometry.net, redis)
that some features require.
This project is Copyright (c) T. E. Pickering and licensed under the terms of
the BSD 3-Clause license. See the licenses/ folder for details.