An astrophotograph is a measurement as much as a picture. Somewhere in that frame are catalogued objects with names, a supernova that may or may not have been visible the night you shot it, and possibly a comet that has since moved on. Until now, Tenrankai showed you the pixels and left the rest to you.

This release closes that gap. Powered by seiza, Tenrankai now plate-solves your astronomical images — fitting an exact WCS from the star field itself — and overlays what’s actually in the frame.

Objects in the Frame

Point Tenrankai at a seiza star catalog and object catalog in config.toml:

[astro]
star_data = "/var/lib/tenrankai/astro/stars.seiza"
object_data = "/var/lib/tenrankai/astro/objects.seiza"

Solved images gain an Objects toggle. Flip it and the deep-sky objects in the frame appear as labeled ellipses — NGC, IC, Messier, Sharpless, Barnard — each oriented to its true position angle, alongside tick marks for named stars. Shot a wide field that sits inside a large nebula? Rather than drawing an ellipse around your entire image, Tenrankai notes it in the corner: Field within: Sh2-276.

Labels nudge themselves out of each other’s way, so a crowded field stays readable.

Solving Without Coordinates

If an image’s sidecar carries ra and dec, that’s the solver’s starting hint. But plenty of images don’t have coordinates — and typing them in for a decade of archives is nobody’s idea of a good evening.

So mark the folder instead:

+++
title = "Deep Sky"
astro = true
+++

Now hint-less images in that folder (and below) get blind-solved: seiza searches the star field with no starting position and finds the answer. Your landscape photos are never blind-solved — the flag is what grants permission.

Solutions are persisted next to the image, so the work happens once.

Supernovae, Scoped to the Night You Shot

Point transient_data at a supernova catalog and solved images get live markers for transients in the frame.

The interesting part is the scoping. A supernova discovered last week has no business appearing on an image you took in 2019 — and equally, one that was blazing away the night you shot should be marked. So Tenrankai reads each image’s capture date and shows the transients that were plausibly there: from a year before the exposure through a month after. Everything else hides behind a quiet “+N old transients” toggle.

The catalog file is reloaded whenever it changes on disk, so a nightly cron keeps your entire archive current with no restart and no reprocessing:

0 4 * * * seiza build-data transients -o /var/lib/tenrankai/astro/transients.seiza

Comets and Asteroids, Where They Actually Were

Minor bodies move, which makes them a poor fit for anything precomputed. Give Tenrankai a minor_body_data file of orbital elements and it propagates every comet and asteroid to the exact moment of your exposure, then projects it through your image’s solution.

They’re drawn with orientation, not just position: comets get a dash along the anti-solar tail direction, asteroids a dash along their motion trail — pointing the way the smudge in your frame is actually pointing. Each is labeled with brightness and distance, like V~11.4, 1.83 AU.

Because they’re computed live from the capture date, nothing is ever stale.

Overlays Everywhere

The overlay isn’t confined to a single view. It rides along:

  • Into the zoom. Toggle objects on, then pinch-zoom on a phone or use the desktop loupe — the overlay scales with the image and stays put. Controls are positioned so they don’t fight your gestures.

  • Into your posts. Gallery images embedded in a blog post carry a compact Objects pill, and so do post hero images — as long as the hero is referenced as a gallery image:

    hero_image = "gallery:main:astro/ngc3310.jpg"

Write up an observing session, and the images in the write-up are just as annotatable as the ones in the gallery.

Catalogs Change; Your Solutions Don’t Have To

When you update the object catalog, Tenrankai doesn’t re-solve anything. The WCS is already stored, so objects are simply reprojected through it — milliseconds per image, either lazily on first view or in bulk:

tenrankai astro regen -g main
tenrankai astro regen -g main --dry-run   # See what would change

Quietly Optional

All of this is gated behind can_see_technical_details, the same permission that governs the rest of your technical metadata — so overlays are for the audience you choose. And with no [astro] section in your config, none of it exists: Tenrankai remains the same plain, file-based gallery it has always been.

Full setup, catalog generation, capture-date rules, and the API are documented in the new Astrophotography guide.