Data Sources & Attribution
Clear-Skies Club relies on trusted astronomical datasets and APIs to provide accurate observation planning. We respect each provider's terms of use and provide proper attribution as required.
JPL Horizons
https://ssd.jpl.nasa.gov/horizons/Purpose
Solar system ephemerides, planetary positions, and orbital mechanics
How We Use It
We use JPL Horizons data for computing accurate positions of planets, moons, and other solar system bodies. Rise/set/transit times are calculated using validated JPL kernels.
License
Public domain (U.S. Government work)
Attribution
NASA/JPL-Caltech
Minor Planet Center (MPC)
https://www.minorplanetcenter.net/Purpose
Asteroid and comet orbital elements
How We Use It
Orbital data for asteroids and comets, including potentially hazardous objects and bright periodic comets visible in amateur telescopes.
License
Free for non-commercial use with attribution
Attribution
International Astronomical Union Minor Planet Center
Pan-STARRS / MAST
https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.htmlPurpose
Deep-sky object imagery
How We Use It
Survey imagery for deep-sky objects including galaxies, nebulae, and star clusters.
License
Publicly available with attribution
Attribution
Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation.
Digitized Sky Survey (DSS)
https://archive.stsci.edu/dss/Purpose
All-sky photographic survey imagery
How We Use It
Fallback imagery for objects not covered by Pan-STARRS. Used for finder charts and visual references.
License
Publicly available
Attribution
Space Telescope Science Institute / Digitized Sky Survey
NASA Image Library
https://images.nasa.gov/Purpose
Astronomical imagery and photographs
How We Use It
Featured images, planetary photography, and educational content. Each image includes specific attribution as required.
License
Generally public domain unless otherwise noted
Attribution
NASA
N2YO Satellite Tracking
https://www.n2yo.com/Purpose
Satellite orbital data and visible pass predictions
How We Use It
International Space Station (ISS) and bright satellite pass predictions. Two-Line Element (TLE) data refreshed regularly.
License
API access with attribution
Attribution
N2YO.com satellite tracking service
OpenWeather
https://openweathermap.org/Purpose
Weather forecasts and cloud cover data
How We Use It
Local weather forecasts, cloud cover percentage, visibility conditions, and sunset/sunrise times for observation planning.
License
API subscription (ODbL for data)
Attribution
OpenWeather
Skyfield
https://rhodesmill.org/skyfield/Purpose
Astronomical computations library
How We Use It
Python library used for high-precision astronomical calculations including object positions, rise/set times, and coordinate transformations.
License
MIT License
Attribution
Brandon Rhodes
HYG Star Database
https://github.com/astronexus/HYG-DatabasePurpose
Star catalog for bright stars and constellations
How We Use It
Star field rendering, finder charts, and constellation identification.
License
CC BY-SA 4.0
Attribution
Compiled by David Nash from Hipparcos, Yale Bright Star, and Gliese catalogs
Licensing & Commercial Use
We cache and attribute data according to each provider's terms of service. Most sources permit free use for typical astronomy applications with proper attribution.
For high-volume commercial use or API rate limit upgrades, additional licensing may be required from individual providers. We will surface any necessary licensing information to commercial users as needed.
Last updated: December 2025
Questions about data usage or licensing? Contact us