A real star map. A wandering telescope.

The background contains 25,791 stars from the HYG v4.1 catalog, selected to apparent visual magnitude 7.5. Every star has a fixed position on a celestial sphere. The view pans, turns, rolls, and changes its field of view while those positions stay unchanged.

What is real

Right ascension, declination, apparent magnitude, and available B–V color indices come from the catalog. The initial view explores Orion and its surroundings. Returning to a camera position restores the same star pattern; resizing the window does not generate a new sky.

What is a visual interpretation

The camera follows a slow, continuous tour. Its movement, zoom, display colors, and brightness curve are chosen for reading comfort. This is a catalog-based visualization, not a telescope photograph or a live view from your location. Positions use the catalog’s J2000 epoch; the display does not calculate current proper motions, atmospheric effects, planets, or satellite orbits.

Source and license

Star data: HYG Database, David Nash / Astronomy Nexus. HYG v4.1 and this adapted subset are available under Creative Commons Attribution-ShareAlike 4.0.

The adaptation selects stars by magnitude, excludes the Sun, retains five positional and photometric fields plus available proper names, converts right ascension to degrees, rounds coordinates, and serializes the result for the web. Full attribution and transformation notes · Download the adapted catalog.

Every 15 seconds, a visible star is circled and identified by its catalog name or HYG ID, with its apparent magnitude beneath. The label stays fixed while its connector follows the star. The Observatory control panel can pause the camera and annotation cycle, or lock the annotation to a chosen star. The “Starfield” toggle on the website hides the entire background. Reduced-motion preferences are respected automatically.

The homepage opens with 20 seconds of brighter sky, identifying a star every 3 seconds during this opening. Once the homepage starts to fade in, annotations slow to every 15 seconds, followed by the sky settling to its quieter reading brightness. “Enter site” or Escape skips the opening; reduced motion shows the content immediately. Reloading the homepage replays the moving telescope, including when the address ends in a fragment such as #main. Saved pause and visibility preferences take effect after the opening finishes.

Origins and development

Observatory grew out of my interest in amateur astronomy. This visualization was coded using GPT 6 Astra.