Hello HN!

As an amateur astronomer living in New York City, finding objects in the night sky has always been a huge challenge. I thought about using the smartphone's gyroscope and magnetometer, but the accuracy left a lot to be desired.

Then I learned about plate solving: given a picture of the sky, we can determine exactly where in the sky the camera was pointing by identifying the star pattern. This was a much better fit - as long as the phone and the optics are rigidly connected, we can repeatedly photograph the sky and determine the pointing direction with very high accuracy.

A lot of work was done to design an algorithm that works reliably with smartphone cameras, which have limited light sensitivity and wider field of view which includes buildings and trees. I experimented a lot with machine learning, and to my surprise, traditional CV methods actually performed better at extracting stars from the image.

The result is AstroHelm, an iOS and Android app that helps figure out where your telescope or camera is pointing, and guides you to the object of your choice. Just follow an arrow on screen, and the object will land right in your eyepiece or viewfinder. Everything happens on device, and no internet connection is required.

AstroHelm is free to use and comes with beginner-friendly objects selected for each night. Optional one time purchases unlock more objects and advanced features, such as interoperability with other astronomy software. I am also proud to partner with astronomy clubs and organizations to offer free licenses for outreach.

I hope AstroHelm can make it a little easier to discover the wonders of the night sky, and I look forward to your feedback!

Hey, I'd actually use that. I build telescopes (see personal site in profile) and only do visual astronomy. I voluntarily prefer to use old-ish phones, i.e. currently I am using an iPhone SE 2022. Do you think the weak signal under the night sky would work with your plate solving ?

This looks like a nice alternative to PiFinder. No extra hardware required. https://www.pifinder.io/

Good call ditching ML. Traditional CV still wins on power, latency, and determinism for star centroiding.

- Accurate up to within 10 arcseconds (1/360 of a degree)

- Computes coordinates in less than a second

For comparison, the sky moves 15 arcseconds per second. So without a motorized mount to keep the telescope on target, the accuracy will be short-lived.

This looks great, but why is there no "plus" version for Android?

I often use Stardroid/SkyMap for this, which is free (open source) software

https://github.com/sky-map-team/stardroid

>"Works Offline

The best dark-sky sites don't have Internet access. AstroHelm’s plate solving engine runs entirely on device. No internet connection required, and your camera images stay on your phone."

This looks like a great tool for the following application:

o Off-grid, deep wilderness, high mountain, broad desert or ocean navigation (like the way ancient seafarers would navigate via the position of the stars in the nighttime sky, relative to them)

(Also, if you're a Star Trek fan and/or futurist, you'd expect that computers on future spacecraft would or could run some version of this software, or at least some form of Plate Solving / Astrometric Solving algorithm...)

Anyway, the app looks great!

Related:

General wikipedia information page about Astrometric Solving (does not include algorithms!):

https://en.wikipedia.org/wiki/Astrometric_solving

Paper: New Algorithms for Automated Astrometry, by Chris Harvey (2004) (An excellent paper about all that is necessary for such an algorithm!):

https://cs.nyu.edu/home/people/in_memoriam/roweis/papers/Har...

Cool project!

Pls fix (AI slop?):

  Unsupported: Smartphone Eyepiece Adapter
  Eyepiece adapters hold the phone’s camera over the eyepiece so you can photograph through the telescope. AstroHelm does not support this configuration. The field of view is typically too small for plate solving to work

“After that, whatever I called for was in the field of view, even when I was using a 5mm eyepiece.”