Last revised 29 September 2026
How this is put together
What Deep Field publishes, where every part of it comes from, how accurate the computed parts are, and what to do when one of them is wrong.
Two halves, and they are not the same kind of thing
About a twentieth of the words on this site are headlines and standfirsts belonging to the publications that wrote them. They are here as pointers: a headline, a clipped summary and a link straight back. Nothing is reproduced at length, no article body is ever copied, and every one carries the name of the publication on the same line. If you want the piece, the link is the piece — a summary that replaces the click has taken something.
Everything else is written or computed here. The glossary, the subject essays, the notes on each of the 110 Messier objects and the copy on every page are ours. So are the tables: what an object needs to be seen, how dark a place is, what the sky does from a given latitude. Those are not looked up anywhere, which is the reason this site exists — and it is also why the next section matters.
The computed parts are a model, with error bars
Whether you can see an object is worked out from its surface brightness against the brightness of the sky, plus what the aperture gathers. That is a real model and it is not a measurement. It does not know your eyes, your transparency, your seeing, how well dark-adapted you are, or whether the object is behind a tree. Treat a verdict of challenge as "some people will, some will not" rather than as a promise.
Sky brightness is estimated from satellite data, not measured. NASA's night-lights composite gives light leaving the ground; that is spread by an approximation of how light scatters and cut into nine bands anchored to places whose skies are known. Checked against twenty such places the ordering is right everywhere and the class is within one almost everywhere. That is the honest claim: good enough to tell a Bortle 3 from a Bortle 7, not good enough to argue a 4 against a 5. The plate resolves to about seven kilometres. A real measurement is a sky-quality meter pointed at your own zenith on your own night, and cloud, humidity, snow cover and the Moon all move it.
The Moon and the planets are computed from truncated series, accurate to about a degree — enough to say where something is, not enough to point a telescope with. Distances to deep-sky objects are the commonly cited values and most are uncertain at the ten per cent level, globular clusters especially. They are there to give a sense of scale, not to be quoted in a paper.
Where a page can only answer a question by guessing, it does not answer it. Rise and set times, which depend on where you are standing, are not on any page that does not know where you are standing. A confident wrong time is worse than no time.
How a story gets filed
Each subject has a hand-built vocabulary weighted by how decisive a term is: event horizon settles the question, orbit barely counts. The full list for each subject is printed on that subject's own page — nothing is hidden and nothing is inferred. A story can land under two subjects and often should. Anything that matches nothing stays untagged and runs in the main feed rather than being pushed somewhere to fill an empty field.
Nothing on this site is generated by a language model. The gather is a feed reader and a classifier; the writing is writing.
Photographs
Frames from ESA/Hubble, ESA/Webb, ESO and NOIRLab are used under CC BY 4.0 and credited as that licence requires; NASA material is generally public domain. The credit line comes through from the source unaltered and every frame links back to its own release page, where the full-resolution master and the observing details are. Where a caption is the observatory's, it is the observatory's — those pages carry no claim to be our writing and ask not to be indexed as though they were. Full credits are on the credits page.
Corrections
If a figure here disagrees with something you have checked, it is worth telling us: these are computed pages and an error in the model is an error on a hundred of them at once, which makes a single report unusually valuable. Corrections are made in the source, take effect on the next build — which runs every three hours — and material ones are dated on the page they affect.
Write to hello@cantinalabs.dev. The site is written and maintained by Dallin Buckles, who answers it.
Advertising, and what it does not buy
This site carries advertising, and no advertiser has ever been shown a page before it went up, asked for one, or been told what is on the way. There is no sponsored content here and no affiliate link on any page. Advertising does not appear on pages that are not asking to be read — the error page, the search box, the embedded scenes — and it does not appear on the photograph pages or the digests, because those are mostly other people's words and monetising somebody else's caption is not a thing this site is willing to do.
What is on the page is decided by the same rules whether or not it earns anything, and the privacy page says exactly what the network sets in your browser.