Constellate

Pick a moment and a place. Constellate computes the sky as it actually stood there — every star down to the naked-eye limit, the constellation figures, the Moon at its true phase, and the planets that were above the horizon — and typesets it as a poster you can print. A REAL CALCULATION, NOT A DECORATION Positions come from the Yale Bright Star Catalog and the VSOP87 and ELP-2000 theories, with precession, nutation, aberration and local sidereal time all applied. Every position is checked against NASA JPL's Horizons ephemeris: the Sun and planets agree to better than one arcsecond, the Moon to about five. A printed dot at 300 DPI on an A2 sheet covers about a hundred arcseconds, so the map is right far below anything the paper can show. BUILT TO BE PRINTED Export a true vector PDF with the fonts embedded — sharp at any size, ready for a print shop, with 3 mm bleed. Or export a PNG at a genuine 300 DPI, up to 5,471 x 7,271 pixels for an 18 x 24 inch print. Four print sizes: A3, A2, 12 x 16 in and 18 x 24 in. FOUR COLOUR TREATMENTS, THREE TYPOGRAPHIC ONES Midnight, Ink, Parchment and Blueprint. Almanac in Garamond, Meridian in Jost, Ledger in Space Mono. Choose constellation figures, the horizon circle, an altitude grid, planet labels and star density. IT WORKS ON A PLANE, PERMANENTLY The star catalogue, 34,125 cities and the full IANA timezone database are bundled in the app. There is no geocoding service and no network call of any kind. And because the timezone rules are the historic ones, a 1987 poster uses 1987's rules — Portugal ran on Central European Time from 1992 to 1996, and Constellate knows. NO DATA COLLECTED. NO DATA SHARED. There is no server, no account, no analytics, no crash reporting and no advertising. Your posters stay on your device, encrypted. Nothing is uploaded, because there is nowhere to upload it to. ONE PAYMENT Design and preview for free. A single purchase removes the watermark and gives unlimited exports forever. No subscription. Ever.