The real sky over a real place, at a real minute. Pick the date, the time and the town, then download a print-ready vector PDF up to 24x36 inches, plus a 4000px PNG. Free, no signup, no watermark.
Every star is positioned by calculation from the date, the minute and the coordinates. Get the time zone right and the sky is right.
North and East are positive, South and West are negative. Pick the offset that applied on that date, including summer time if it was in force. There is no time zone lookup here, so this one is on you.
Any date from 1900 to 2100. Outside that range the sky is not drawn.
Leave a field empty to drop that line from the poster. The layout closes up around it. Edit the date, place or coordinates line and it stops following the place and date you picked above.
Balanced stops at magnitude 5.5, roughly what a good dark sky shows the naked eye. Everything goes to 6.0 and starts to look like static.
The known ones covers 46 figures, everything most people could name. All 88 fills the sky in and reads busier.
The PDF is vector, so the stars stay sharp at any print size. The PNG is 4000 pixels on the long side, made for screens, and a last resort for a print shop that will not take a PDF.
Star positions come from the Hipparcos catalogue, cut to magnitude 6.0, which is about 5,000 stars and everything a naked eye can pick out on a clear night. The page works out the Julian day from your date and time, converts it to Greenwich Mean Sidereal Time, adds your longitude to get local sidereal time, turns every star's right ascension and declination into an altitude and azimuth for your latitude, and projects the visible half of the sky onto a circle with a stereographic projection. Catalogue coordinates are for the year 2000, so they are also precessed forward or back to your date, which matters by about half a degree for a birthday in the 1950s. Dates are accepted from 1 January 1900 to 31 December 2100, so an older birth or an anniversary further back than 1900 cannot be drawn here.
Your local time is converted to UTC using the real time zone rules your browser already carries, which includes summer time as it was on that date, not as it is now. An hour of error would rotate the whole sky by 15 degrees, so this is the part that usually goes wrong in other tools.
It does not draw the Moon, the planets, the Milky Way or deep sky objects, and it does not shade for daylight, so a map for two in the afternoon is drawn exactly like a map for two in the morning. It does work out where the Sun was and tells you under the preview when the minute you picked was daylight or twilight, so you can move it if you meant a sky someone could actually see. It is the star field, honestly computed, and nothing else.
Send the PDF, not the PNG. It is a vector file, so the stars are real circles and the lettering is real type, and a print shop can scale it to any size without softening. It has no bleed and no crop marks, so ask for it printed to size rather than trimmed, or tell the shop to add its own bleed.
Dark posters eat ink and can band on cheap presses. If you are printing at home or through a budget service, the light colour option prints cleaner and is usually the safer choice. Matte paper suits a star map better than gloss.
The PDF uses the standard print fonts that every PDF reader carries, which cover the Latin alphabet including accents. Characters outside that, such as Cyrillic, Greek, Arabic, Hebrew, Chinese, Japanese or Korean, cannot be embedded and are dropped from the PDF. Letters that sit just outside it, Ł and ż and ő for instance, print as the nearest plain letter. You get a warning under the preview in both cases. A few marks that do print are quietly swapped for their plain equivalents so they come out right on every reader: curly quotes become straight ones, long dashes become hyphens, an ellipsis becomes three dots. The PNG keeps whatever you type exactly as you typed it.
The framed star map is one of the most reliably sold gifts on the internet. A printed one runs roughly $60 to $100, and the digital file on its own still goes for $25 to $40. Free generators do exist, which is worth saying plainly. What they hand back is a screen resolution image, usually around 1000 pixels wide, which looks fine on a phone and falls apart the moment a print shop scales it to A1. This page gives you the vector PDF instead, the same kind of file the paid sites sell, so a 60 by 84 centimetre print stays crisp.
Three things decide whether the map is the real sky or a pretty pattern. The date sets which constellations are up at all. The time of night sets how far the whole sky has rotated, and one hour off turns it by 15 degrees, which is very visible once someone who knows Orion looks at it. The place sets your latitude, which decides what never rises and what never sets. Pick the town from the list wherever you can, because that carries the time zone with it and handles summer time as it stood on that date rather than today.
The night we met, a wedding date, a birth, a first house, the last night of a trip. The big line is usually two names or one name, the small line above it is the occasion, and the lines below are the date, the town and the coordinates. Anything you leave blank simply disappears and the layout closes up, so a plain map with a single date underneath is one deletion away.
The catalogue, the constellation figures and the city list all ship inside this page, and the astronomy runs in your browser. The date you type, the place you pick and the names you write are never sent anywhere, and nothing is stored between visits.
Star positions and constellation figures come from d3-celestial by Olaf Frohn, BSD 3-Clause licensed, derived from the Hipparcos catalogue. City coordinates and IANA time zone names come from city-timezones by Kevin Roberts, MIT licensed. PDF writing uses jsPDF 2.5.2. Time zone rules come from your own browser.