Frequently asked questions
Answers about using StargazerKit, accuracy, privacy, and how you can help us improve.
Is StargazerKit really free?
Yes. Every tool is free to use, unlimited times, with no daily cap and no credit card. There are no paid tiers, no hidden quotas, and no premium unlocks. The site is supported by its creators and kept intentionally lightweight.
Do I need an account or API key?
No. We never ask for login credentials, email addresses, or API tokens. The few tools that call external data sources (such as weather or near-Earth object lookups) use public, keyless endpoints like Open-Meteo and NASA's NeoWs demo key.
Where does the astronomy data come from?
Most calculations run natively in your browser using standard astronomical approximations (Meeus-style algorithms, Kepler solvers, Conway moon-phase, NOAA sunrise/sunset). Live data tools pull from public APIs: Open-Meteo for weather, NASA JPL NeoWs for asteroids, and static event tables for meteor showers and eclipses. Each tool detail page lists its exact source and method.
How accurate are the results?
The native algorithms are accurate enough for backyard planning and observation: Moon phase to within a percent, planet positions to within a few arcminutes, and sunrise/sunset to within a minute for most locations. For professional astrometry or telescope pointing, please use a dedicated ephemeris such as JPL Horizons or a planetarium app like Stellarium.
Can I use the site offline?
Once the page is loaded, most calculators are pure JavaScript and work without a network connection. The live-data tools (weather, near-Earth objects) obviously need an internet connection. The site itself is a static export, so it can be served from a CDN or saved locally if you wish.
Why do I see a default location for some tools?
Tools that depend on latitude and longitude (sunrise/sunset, stargazing weather) default to a common northern hemisphere reference (often 40°N, 0°E) so you can see a result immediately. Most of them let you type or select your own coordinates or city for a local calculation.
What is a 'zenith hourly rate' (ZHR)?
ZHR is the theoretical maximum number of meteors a single observer would see under perfect conditions: the radiant directly overhead, a dark magnitude-6.5 sky, and no obstructions. Real-world counts are almost always lower because of light pollution, weather, and the radiant's altitude at your location.
Why doesn't the telescope calculator replace my planetarium app?
It isn't meant to. StargazerKit is a field-notebook: quick optics math, unit conversions, and planning checks. Planetarium apps give you immersive sky maps and full ephemerides; use both together.
Is my data collected or tracked?
No personal data is collected. Calculations happen in your browser, and we do not run analytics trackers, advertising pixels, or session recording. See our Privacy Policy for the full details.
Can I link to a specific tool?
Absolutely. Every tool has its own URL, e.g. /tools/moon-phase-calculator. You can share links directly, bookmark them, or embed them in observing-group messages.
How do I report a bug or suggest a new tool?
Use the Contact page to send a short message. Include the tool name, the inputs you used, and the result you expected. We read every message and use it to prioritize fixes and new calculators.
Can I use the code for my own project?
The algorithms are plain TypeScript and built on well-known public formulas. You are welcome to study and reuse the mathematical approaches for personal, educational, or non-commercial projects. For the specific site's branding, design, and assembled content, please contact us first.
Still have questions?
We read every message. Reach out through the contact page and we'll get back to you.