It's "hangar", not "hanger", dammit!
I thought the article was going to tell us about a secret clothes closet aboard the new bomber.
Finding the B-21's hangar location from the stars in its press image
141–150 of 228 posts
Re: Finding the B-21's hangar location from the stars in its press image
#142This is quite the boondoggle, not a lot of change out of billion dollars per aircraft, remember that as you work yourself to death.
"Stealth" has such a limited life span of utility. Even in the 90s Serbian air defence managed to acquire and shoot down "stealth" aircraft. It required humint but that's part of a real theatre of war.
Re: Finding the B-21's hangar location from the stars in its press image
#143Earlier quoted context omitted.
The claims from pifm_guy are reasonable. This is a scenario with extremely high coding gain[1]. The DC value of the sky can be removed by high pass filtering. Finding the rigid transform (rotation+translation) between two images captured by the same camera, assuming no distortion[2], assuming the image pair has substantial intersection, doesn't require calibration. Dropping the "same camera" and "substantial intersec…
If the "DC value of the sky" could be removed with a simple high pass filter, then there would be no need of doing anything else. The positions of the stars in the sky would be known, and techniques like the one in the article would apply. I have been working fine so far in startrackers for spacecraft without your tutorial in signal processing, but thanks for the offer
> If the "DC value of the sky" could be removed with a simple high pass filter, then there would be no need of doing anything else. The positions of the stars in the sky would be known, and techniques like the one in the article would apply.
This doesn't make any sense. Even if one could estimate ground truth DC, removing it would leave noise at every other frequency bin.
But this is beside the point. Your questioning isn't coming from a place of curiosity.
I direct you to the HN guidelines: "Be kind. Don't be snarky. Have curious conversation; don't cross-examine."
Re: Finding the B-21's hangar location from the stars in its press image
#144Sky obfuscation to avoid stellar triangulation as a service?
Re: Finding the B-21's hangar location from the stars in its press image
#145I feel like the entire thread should have led off with "This is in fact a publicly known hangar in Palmdale and this was known as public information as soon as the unveiling event occurred, and thus this is just an exercise to show how locating the spot could have been possible from just this photo as a technical demonstration." Because I guarantee there are going to be a hundred clickbait articles by various 'news'…
People have been doing photo analysis for a long long time, and have gotten quite good at doing geolocation based on details in the background that the average viewer ignores. Spy agencies are especially good at it. There's many a spy movie that offers glimpses into this, but The Good Shepard comes to mind. Even as a joking kind of thing, the opposite has been done. There's a famous exchange between Neil DeGrasse Tys…
> It's a game to some people. It's a challenge.
GeoWizard on youtube has a whole series where he tries to pinpoint the exact locations of pictures sent to him by fans. Pretty fun to watch:
https://youtube.com/playlist?list=PL_japiE6QKWqMVC3JbyONau_0...
Re: Finding the B-21's hangar location from the stars in its press image
#146Earlier quoted context omitted.
It doesn’t fly yet, so that narrows it down a bit.
Do they’re trying to scare Russian with an airplane that can only be taxied around? I wonder if it’s made out of proper material and not just some clay concept
The US has retired planes decades ago that are superior to the best Russia has today, so no I doubt we really care about Russia's thoughts. China maybe.
Re: Finding the B-21's hangar location from the stars in its press image
#147Earlier quoted context omitted.
Not only that, they had three bombers (B1, B2, and B52) fly over during the live stream of the unveiling that could be tracked live on commercial flight tracking websites. This simply wasn’t a secret at all.
This livestream is the best caricature of American culture I've seen, thank you. It is the unveiling of a bomber, with the national anthem sung by an employee of the company who built it, as in a proper performance, while more bombers fly ahead so loudly he has to stop. Then it proceeds to have the CEO read an engineered speech from a teleprompter, completely devoid of her own existence. Followed by a hollywood actio…
Yeah, clearly only Americans do this. Ignore the fact that monarchs have been christening ships for thousands of years.
Re: Finding the B-21's hangar location from the stars in its press image
#148Wow, 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.
is A,B,C,D in the database the same as D,C,B,A? Or does order infer orientation?
Order cannot infer anything. Only people, animals, and some programs can infer. Inanimate facts can at most imply.
Re: Finding the B-21's hangar location from the stars in its press image
#149There'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…
Interesting. So do you think the author had inside information on the location?
Re: Finding the B-21's hangar location from the stars in its press image
#150There'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…
Interesting. So do you think the author had inside information on the location?
It was publicly accessible, or so I've read at least