Clear-Skies.club
FAQ

Clear-Skies.club is an observation planning web app that helps amateur and pro astronomers plan observing sessions. It recommends targets, shows visibility windows, integrates weather and satellite passes, and exports printable plans.

Yes, an account is required to use the planner. We use passwordless email authentication (OTP-based login) for secure access. Once logged in, you can save your location, create observation plans, log observations, and export your plans.

Clear-Skies.club is a responsive web application that works on any modern browser — desktop, tablet, or mobile. No app installation required.

Open the Planner, enter your location (city name or coordinates), set your observation date and start time, then hit the Plan button. The planner will calculate visibility windows for hundreds of targets and rank them by altitude, darkness, and your equipment profile.

Yes. After generating recommendations, you can add or remove targets, reorder them, and annotate each with notes. Sessions can be exported as PDF, CSV, or JSON for offline use or printing.

Rise, set, and transit times are calculated using JPL Horizons ephemeris data and are accurate to within a few seconds for solar system objects. Deep-sky object positions use the HYG star database with precession corrections.

The planner automatically calculates astronomical twilight, civil twilight, and moonrise/moonset for your location and date. Targets are scored against moon separation and sky brightness to surface the best options for your specific night.

We use JPL Horizons (solar system ephemerides), Minor Planet Center (asteroid/comet orbits), Pan-STARRS/MAST and DSS (deep-sky imagery), N2YO (satellite tracking), NOAA GFS and Himawari-9 (weather/cloud data), OpenWeather (forecasts), and the HYG Star Database. Full details on the Data Sources page.

Most sources are public domain or freely available for non-commercial use with attribution. We comply with each provider's terms of service and cache data responsibly. See the Data Sources page for per-provider licensing details.

Deep-sky object thumbnails are sourced from Pan-STARRS, DSS, and NASA Image Library — all publicly available with attribution. We do not host or redistribute copyrighted imagery.

We use passwordless email authentication (OTP). Enter your email, receive a one-time code, and you're in. No passwords to remember or lose.

Plans can be exported as PDF (print-ready), CSV (spreadsheet-compatible), or JSON (machine-readable). Export options appear on the session summary screen after planning.

Your location is used solely to calculate sky positions and visibility windows. City-level location may be saved to your profile with your explicit consent. We never sell, share, or transfer location data to third parties.

We collect only your email, city-level location, and observing preferences. Data is used within your session for calculations and not permanently stored unless you explicitly save it. Read the full Privacy Policy for details.

Equipment management is a planned feature. In future releases, you'll be able to add telescope, mount, and camera specifications to your profile, which will help the planner provide more tailored recommendations based on your equipment capabilities.

Mount control (ASCOM/INDI) is a planned advanced feature. Initially we will support export formats that third-party mount software understands so you can import target lists.

A public API is planned for future releases to let power users query visibility metrics and manage saved planners programmatically. For now, please reach out if you have integration needs.

Minor differences (< 1 minute) are normal due to atmospheric refraction models and epoch differences. Larger discrepancies usually indicate a location or timezone mismatch. Double-check your coordinates and UTC offset in the planner settings.

Satellite pass data comes from N2YO and is updated every few hours. Very low-elevation passes (< 10°) are filtered out by default. Newly launched satellites may not appear until their TLE data is propagated. Try refreshing or checking back later.

Use the Contact page to send us a message. Include your location, date/time, browser version, and a description of the issue. For feature requests, describe your use case and we'll add it to the roadmap.