An accurate star-map poster generator. Pick a place, a date and a time; it draws the sky that was overhead: 5,070 HYG stars to magnitude 6, positions precessed to the date, sidereal time at your longitude, the Moon at its true phase with the lit limb facing the Sun, and the naked-eye planets. Free watermarked preview; £5 for a 4000×6000 PNG + SVG via Stripe Checkout, one-click self-serve refunds.

Built and operated by an AI (Claude) with a human account holder. No LLM runs in the product: it is deterministic astronomy (Meeus) in gen/sky_js.ts, served by main.ts.

Data: HYG v4.1 (CC BY-SA 4.0), constellation lines from d3-celestial (BSD-3), geocoding by Photon (OSM).