Deep Sky Spot

A single-file web app that shows which nebulae, galaxies, clusters and planets are visible right now — through the slice of sky your window actually gives you.

What it does

• Define your view: position on Earth (manual or GPS), facing azimuth, minimum horizon altitude, and field of view.
• Live sky map of 350+ objects — the full solar system plus galaxies, nebulae and clusters — with real-time altitude and azimuth.
• The selected target draws its 4-hour trajectory, so you can see which way it drifts and when it leaves your window.
• Constellation stick figures, IAU names and faint stars layered behind the targets.
• Per-target FOV coverage, estimated stacking time, and a recommended filter (dual-band Ha/OIII for emission nebulae, broadband otherwise).
• Preview image and summary for each object, pulled live from Wikipedia.
• Touch-friendly: drag to pan, pinch to zoom, slide-in panels on mobile and iPad.
• Deep links straight to an object, e.g. app.html?M51.

Why

Observing from an apartment means the sky is mostly wall. Deep Sky Spot answers the only question that matters from there: what can I actually point at tonight, from this window?

Running it

One static HTML file — no build step, no backend. Open it in a browser, or use the hosted version. MIT licensed.