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Finding the B-21's hangar location from the stars in its press image

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Re: Finding the B-21's hangar location from the stars in its press image

#211

Post by malfist »

mierle wrote: post #26

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.

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.

Re: Finding the B-21's hangar location from the stars in its press image

#212

Post by malfist »

4gotunameagain wrote: post #88
pifm_guy wrote: post #75

Earlier quoted context omitted.

In my case, I had nighttime images from the same camera, so all the calibration was already done... I was just looking for a rotated version of the nighttime image in the daytime image. But even in the general case, smallish image patches don't have enough distortion to matter, while still having plenty of oversampling, and only have 3 unknowns. You can probably do some kind of fft trickery to reduce it to 1 unknown.…

What does an optimization algorithm have to do with a brute force search? Even if your image patch is small, without previous images to compare, you need to brute force the entire sky? And how can "fft trickery" reduce the attitude state to 1 unknown ? 1 unknown with what units ? Sorry but I suspect you are making all these up.

It might be helpful if you read about what platesolving is: https://en.wikipedia.org/wiki/Astrometric_solving

It's a well defined problem of taking star positions and pinpointing its celestial coordinates. There's even a term for being able to do that without knowing anything about the camera, telescope or distortion, it's called blind solving. Plenty of tools to do it are available online and they're an essential part of an astrophotographers tools.

Fun fact, most of our ICBMs rely on plate solving to navigate so they can hit their targets even when GPS signals are disrupted.

Re: Finding the B-21's hangar location from the stars in its press image

#213

Post by greggarious »

whywhywouldyou wrote: post #171
gmiller123456 wrote: post #140

There's a few highly suspect details in the way the author got the 34-35 degree estimate. Maybe he was just really lucky and the errors cancelled out, but don't count on using his method to produce similar results. Polaris is about .8 degrees away from the celestial North pole, so using it alone can give a reading off by .8 degrees, and the orientation in the photo is actually nearing the worst case. The horizon does…

I'm sure you're correct, as the whole thing reads like "look how smart I am". 1. Extraneous details about satellites not being overhead at night -- as if government spy satellites operate on the same schedule with the same priorities as publicly known satellites. 2. Mentions things like them not scrubbing the EXIF data was a "mistake". How could it be a mistake if this was public information? 3. Says at the end "(thi…

> I'm sure you're correct, as the whole thing reads like "look how smart I am".

It's been that way for a long time. The whole "UFO movement" had it's flames fanned by agents of foreign power who literally salivate at how many useful idiots will do the work their analysts would have done.

Some officer in the Russian equivalent of the NRO is probably gonna take that post and run with it.

Re: Finding the B-21's hangar location from the stars in its press image

#214

Post by barelysapient »

baxtr wrote: post #182
jaxomlotus wrote: post #154

Earlier quoted context omitted.

If I were a betting man I would assume he started this exercise with the final assumed location in mind, and worked backwards from there to show how it could have been done.

That's actually what he was implying in his last tweet: > The press conference to reveal the aircraft was held here last week so we can confirm the location. A guess likely would have landed someone in the same location but fun anyway to star match. I'm sure this entire process could be done with just stars and no google maps as well

Aka, “parallel reconstruction”

Re: Finding the B-21's hangar location from the stars in its press image

#215

Post by jasonwatkinspdx »

whywhywouldyou wrote: post #171
gmiller123456 wrote: post #140

There's a few highly suspect details in the way the author got the 34-35 degree estimate. Maybe he was just really lucky and the errors cancelled out, but don't count on using his method to produce similar results. Polaris is about .8 degrees away from the celestial North pole, so using it alone can give a reading off by .8 degrees, and the orientation in the photo is actually nearing the worst case. The horizon does…

I'm sure you're correct, as the whole thing reads like "look how smart I am". 1. Extraneous details about satellites not being overhead at night -- as if government spy satellites operate on the same schedule with the same priorities as publicly known satellites. 2. Mentions things like them not scrubbing the EXIF data was a "mistake". How could it be a mistake if this was public information? 3. Says at the end "(thi…

> as if government spy satellites operate on the same schedule with the same priorities as publicly known satellites.

It's basically impossible to hide things in orbit. Hobbyists have been able to track the Misty spy satellite that has an inflatable cone to mask its optical signature. The major powers all operate space tracking radars that can spot anything up there bigger than about a baseball.

Also nearly all optical imaging sats are in sun synchronous orbits because it maximizes power generation vs solar panel size as well allows comparison of multiple days images with the same shadow angles.

> How could it be a mistake if this was public information?

Well they scrubbed the data from the website so that's a pretty clear indication it was a mistake. You're oversimplifying this into a binary thing, whereas a lot of security is more of the form "this isn't foolproof but there's no need for us to make it this easy."

Re: Finding the B-21's hangar location from the stars in its press image

#216

Post by gmiller123456 »

comboy wrote: post #202
gmiller123456 wrote: post #181

Earlier quoted context omitted.

For what it's worth, I measured the pixels between Kochab and Pherkad and got .0161 degress per pixel. Then measured from Polaris to my visual guestimate of where the horizon should be and got 34.14 deg, about half a degree off of the real location. I'd be interested to see what others get. For those not familiar with the stars, Polaris is just a few pixels from the top edge, nearly dead center (it's close enough to…

Wide angle lens distortion?

I thought lens distortion would be a problem too, but there's really not much distortion. The lines on the buildings and runway are all pretty straight, even near the corners of the photo where distortion would be at it's maximum. I'm willing to bet the photographer has a lot of experience photographic large planes and knew what steps to take to avoid it coming out all contorted.

Re: Finding the B-21's hangar location from the stars in its press image

#217

Post by daveslash »

vba616 wrote: post #168
daveslash wrote: post #23

This is very cool sleuthing. Really enjoyed the walkthrough. Though, if you would have asked me, I would have guessed Lancaster/Palmdale, because I know (a) That's where the unveiling was (b) I have seen B-1's fly over me while driving in Palmdale and (c) I know Edwards and a bunch of other spacey stuff is there. I feel like Captain Kirk looking for whales and saying " I think we'll find what we're looking for at the…

Do you mean B-1 or B-2? I thought the B-21 was intended as a successor to the B-2, only cheaper. Also, they look the same to me.

I'm sorry, yes... I meant the B-2, not the Rockwell B-1 Lancer. You are correct. We were driving through Palmdale and I saw one of the B-2 flying wings cruise over the freeway on approach. Was very very cool to see.... But thank you for the correction. B-2, not B-1.

Re: Finding the B-21's hangar location from the stars in its press image

#218

Post by daveslash »

mrexroad wrote: post #87
daveslash wrote: post #23

This is very cool sleuthing. Really enjoyed the walkthrough. Though, if you would have asked me, I would have guessed Lancaster/Palmdale, because I know (a) That's where the unveiling was (b) I have seen B-1's fly over me while driving in Palmdale and (c) I know Edwards and a bunch of other spacey stuff is there. I feel like Captain Kirk looking for whales and saying " I think we'll find what we're looking for at the…

Ahem, not to be that person… but I think you mean Admiral Kirk :) Either way, it’s a perfect reference.

You sir, are correct. Thank you for the correction! Please be that person. Btw, my wife and I were able to visit the Monterrey Bay aquarium for the first time this past November -- and I would just not shut up with the references. My wife loved them, but also was a bit over them by the end.

Re: Finding the B-21's hangar location from the stars in its press image

#219

Post by LarryMullins »

nradov wrote: post #209
082349872349872 wrote: post #204

Earlier quoted context omitted.

Speaking of ICBM's, I'm sure they use more sophisticated targeting now, but in the early days they'd astrogate for any necessary mid-course corrections. (Cannot remember if I saw this procedure on a film narrated by von Braun himself, but I doubt it; I think I saw him in a Disney)

ICBMs still use a mix of stellar and inertial navigation. They can't rely on satellite navigation because in a major conflict those may be destroyed or jammed. Some modern ICBMs might also have some limited terminal guidance capacity but there's not much public information on that subject.

With SLBMs, GPS (and the predecessors to GPS e.g. NAVSAT) are/were used to determine where exactly they were being launched from. The ballistic missile submarine would determine its precise location before launch using these satellite geolocating systems and use that position to calculate the flight path which inertial guidance in the missile would follow.

This was useful because inertial navigation in the submarines was imperfect, but having a precise location fix for the submarine was important if you wanted to shoot at things precisely. Of course with ICBMs launched from fixed silos, the origin point was precisely known from the onset.

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