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Comment by mierle | Hacker News Reader

Wow, it's cool to see astrometry.net get put to use! I worked on astrometry.net back in undergrad and grad school. If you have questions about how it works, I can answer them.

How does it work? astrometry.net uses 4-star combinations to define codes, then indexes the codes on the celestial sphere. The particulars of each of these phases matter, but that's the basic idea.

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I remember my jaw dropping while sitting in a colloquium hearing about astrometry.net from David Hogg back in ...2007?

Fast forwarding a few years, we started using it at SOFIA Observatory to help speed up telescope acquisitions.

is A,B,C,D in the database the same as D,C,B,A? Or does order infer orientation?

It uses a hash which is scale and orientation independent. A lot of the details are described in this paper:

https://arxiv.org/abs/0910.2233

Order cannot infer anything. Only people, animals, and some programs can infer. Inanimate facts can at most imply.

I used to be in astronomy and I always thought astrometry.net was one of the coolest tools in the field. It feels about as close to magic as you can get.

Astrometry.net is damn handy. I don't use it too much these days for myself except for annotating images, but I do have some friends just getting into astronomy and it's blind solve is amazing to help them.

Plus when I show them plate solving their minds are blown. Hugely useful tool.

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