Looks cool! Plate solving is an incredibly useful technology for astronomy, putting it into the smartphone makes it available for a lot of "non-smart" setups. Only one question: does it have a polar align feature? This is my biggest challenge, when e.g. setting up a simple star tracker. The app would be very useful for this.
HeavenFox 46 minutes ago [-]
We have a prototype polar alignment feature in the works! The benefit of plate solving is you can actually do a two-point polar alignment: just take two pictures with different RA, and we will know where the axis is. Taking more pictures would improve accuracy.
jnsie 53 minutes ago [-]
Really dumb question - but how does the phone know the distance from your phone lens to your telescope lens? I assume this varies greatly from mount to mount and will change how accurate the app is?
HeavenFox 44 minutes ago [-]
The distance doesn't matter, since the stars are almost infinitely far away, so there's no parallax. You do need to correct for the angle though. We support daytime alignment using, say, a distant treetop, or at night align on the object you are observing.
jnsie 4 minutes ago [-]
Ah, that's the piece I was missing. Thank you
chantepierre 6 hours ago [-]
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 ?
HeavenFox 1 hours ago [-]
It should. I have users reporting good experience with iPhone XS. It is heavily dependent on your local light pollution levels though.
danbruc 5 hours ago [-]
- 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.
HeavenFox 1 hours ago [-]
Since the plate solving happens periodically, the sky drift will quickly be corrected!
groby_b 1 hours ago [-]
It's meaningless anyway, unless you have a calibration approach the home page doesn't mention. Aligning a phone to within 10 arcseconds of where your scope is pointing is... ambitious :)
It would be easier if you could use an eyepiece adapter. I have no idea why the page claims "The field of view is typically too small for plate solving to work." for that approach - it works just fine with a FOV of at least 0.2 degrees or so, which is much smaller than what most beginner/intermediate scopes have.
And if you do have a scope with a smaller TFOV, I'd argue you're likely not the target audience for the app. (Yes, you can get there cheaply and as a first scope, but it's not the usual route)
Edit: I want to be clear it's not a diss on the app - it's great. Plate solving at that speed is pretty cool. I just wish it'd work at smaller TFOVs :)
HeavenFox 50 minutes ago [-]
So the reason that line of text is there is we designed AstroHelm to be mounted directly on the telescope facing the sky. We don't want our users to go to Amazon and search for "telescope smartphone mount", get an eyepiece adapter, and found that it doesn't work :)
As for why we don't support adding optics between the phone and the sky, there are a few reasons. The accuracy from phone's camera lens is good enough, and we don't want to introduce complexity. The plate solving algorithm also benefits heavily from knowing the field of view, which you get from phone's built in camera but need user input for custom optics. Finally, supporting smaller field of view means shipping a much larger star database which most users won't use, so it's just a waste of storage and bandwidth. Not to mention blind solving a small FoV would be very slow and not work interactively.
For alignment, we support two alignment methods. You can align it like a finderscope, i.e. aim your telescope at a distant treetop and drag the crosshair over it. Once you begin observing, you can also sync to the object, which should give you better accuracy.
solarist 5 hours ago [-]
OP mixed up accuracy and resolution.
skypanther 5 hours ago [-]
This looks like a nice alternative to PiFinder. No extra hardware required. https://www.pifinder.io/
Tepix 2 hours ago [-]
Interesting, thanks.
A related issue I’ve been wondering about: Why don’t gimbals for cameras and smartphones offer an astrophotography mode for long exposures of the night sky?
HeavenFox 1 hours ago [-]
They do! The "night mode" in camera apps all utilize gimbals
soltanov 6 hours ago [-]
Good call ditching ML. Traditional CV still wins on power, latency, and determinism for star centroiding.
fanatic2pope 6 hours ago [-]
This looks great, but why is there no "plus" version for Android?
HeavenFox 1 hours ago [-]
We launched Android recently and was using this opportunity to experiment with pricing and packaging a little bit!
peter_d_sherman 5 hours ago [-]
>"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!):
> The best dark-sky sites don't have Internet access.
I'm spoiled. The best dark-sky site near me, a meager 4 hour drive, is an astronomy campus with fiber internet providing wifi. Intentionally, it's not a lot of bandwidth to do streaming while you're bored, but enough to run apps like this. They also have a what they named the StarField which is an open field where there is a grid where every 10' or so has an electrical outlet popping up from the ground to power your gear. It's the darkest skies in my state that is not federal land.
preisschild 5 hours ago [-]
I often use Stardroid/SkyMap for this, which is free (open source) software
I’m not a professional by any means and am pretty new to astrophotography. Looking at the Stardroid repo there, it looks like it’s using GPS+Compass+IMU for pointing. That’s awesome for coarse positioning, but Plate Solving (what AstroHelm is doing) is using the photos themselves to do fine positioning. https://nova.astrometry.net/ is an open service that can take images and tell you where in the sky you were pointing. https://nighttime-imaging.eu/docs/master/site/advanced/plate... has some more details about different techniques and software packages. My understanding is that is basically identifies the 4-8 most prominent stars in the image and the angles between them and does a nearest neighbour search in a massive database. Pretty cool!
preisschild 2 hours ago [-]
Ah interesting, I thoughy this was also using IMU
rrr_oh_man 6 hours ago [-]
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
But:
“After that, whatever I called for was in the field of view, even when I was using a 5mm eyepiece.”
chantepierre 6 hours ago [-]
They mean that the FOV seen by the phone through an eyepiece is too small to run a successful plate solve.
The comment of the user says "the plate solve was precise enough that the object I wanted was centered (for the observer, not for the phone) when I used a 5mm eyepiece" (which is usually an high-power, meaning tiny-FOV eyepiece)
Most pointing methods aren't accurate enough to correctly center an object at high power and require you to use a lower power eyepiece, nudge the object a bit, then switch to high power. I understand how you read it as slop but the two sentences aren't contradictory, and the user comment hints to an useful pointing tool :)
Edit : bad tenses and grammar fixes
rrr_oh_man 6 hours ago [-]
Thank you for the explanation!
chantepierre 6 hours ago [-]
For more context, the other comment saying "I’m really impressed… guided me almost dead on to the double cluster when asked." is a bit funny, because the double cluster is easily seen naked-eye in suburban sky, which is as easy as it gets for deep sky objects. But the comment you quoted makes the app look good and I'm going to try it if the fall cloud cover ever goes away.
promptspheree 4 hours ago [-]
[flagged]
nateparkerdev 3 days ago [-]
[flagged]
Rendered at 17:38:08 GMT+0000 (Coordinated Universal Time) with Vercel.
- 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.
It would be easier if you could use an eyepiece adapter. I have no idea why the page claims "The field of view is typically too small for plate solving to work." for that approach - it works just fine with a FOV of at least 0.2 degrees or so, which is much smaller than what most beginner/intermediate scopes have.
And if you do have a scope with a smaller TFOV, I'd argue you're likely not the target audience for the app. (Yes, you can get there cheaply and as a first scope, but it's not the usual route)
Edit: I want to be clear it's not a diss on the app - it's great. Plate solving at that speed is pretty cool. I just wish it'd work at smaller TFOVs :)
As for why we don't support adding optics between the phone and the sky, there are a few reasons. The accuracy from phone's camera lens is good enough, and we don't want to introduce complexity. The plate solving algorithm also benefits heavily from knowing the field of view, which you get from phone's built in camera but need user input for custom optics. Finally, supporting smaller field of view means shipping a much larger star database which most users won't use, so it's just a waste of storage and bandwidth. Not to mention blind solving a small FoV would be very slow and not work interactively.
For alignment, we support two alignment methods. You can align it like a finderscope, i.e. aim your telescope at a distant treetop and drag the crosshair over it. Once you begin observing, you can also sync to the object, which should give you better accuracy.
A related issue I’ve been wondering about: Why don’t gimbals for cameras and smartphones offer an astrophotography mode for long exposures of the night sky?
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...
I'm spoiled. The best dark-sky site near me, a meager 4 hour drive, is an astronomy campus with fiber internet providing wifi. Intentionally, it's not a lot of bandwidth to do streaming while you're bored, but enough to run apps like this. They also have a what they named the StarField which is an open field where there is a grid where every 10' or so has an electrical outlet popping up from the ground to power your gear. It's the darkest skies in my state that is not federal land.
https://github.com/sky-map-team/stardroid
Pls fix (AI slop?):
But:“After that, whatever I called for was in the field of view, even when I was using a 5mm eyepiece.”
The comment of the user says "the plate solve was precise enough that the object I wanted was centered (for the observer, not for the phone) when I used a 5mm eyepiece" (which is usually an high-power, meaning tiny-FOV eyepiece)
Most pointing methods aren't accurate enough to correctly center an object at high power and require you to use a lower power eyepiece, nudge the object a bit, then switch to high power. I understand how you read it as slop but the two sentences aren't contradictory, and the user comment hints to an useful pointing tool :)
Edit : bad tenses and grammar fixes