i nerd sniped myself tonight and i imagine the NSA operative who is assigned to me is very confused by the increasingly erratic and frustrated google searches for HOW DO I CALCULATE THE MOON WHERE IS THE MOON
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i nerd sniped myself tonight and i imagine the NSA operative who is assigned to me is very confused by the increasingly erratic and frustrated google searches for HOW DO I CALCULATE THE MOON WHERE IS THE MOON
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i nerd sniped myself tonight and i imagine the NSA operative who is assigned to me is very confused by the increasingly erratic and frustrated google searches for HOW DO I CALCULATE THE MOON WHERE IS THE MOON
I just want to calculate the current direction of tidal force from the observer's earth-relative position in space and time is that so wrong
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I just want to calculate the current direction of tidal force from the observer's earth-relative position in space and time is that so wrong
wikipedia: even the ancient babylonians knew how to use math to figure out what the moon is up to
me: great how do i do that
wikipedia: 😏
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I just want to calculate the current direction of tidal force from the observer's earth-relative position in space and time is that so wrong
@aeva oh boy. I went down the rabbit hole of calculating star positions a few years ago, and the whole thing is... convoluted. Step one was calculating the Earth Rotation Angle, and that was... urgg
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@aeva oh boy. I went down the rabbit hole of calculating star positions a few years ago, and the whole thing is... convoluted. Step one was calculating the Earth Rotation Angle, and that was... urgg
@jon_valdes my hope was that the moon's position relative to the earth would be the one situation where geocentrism still holds enough water for a useful approximation, but I'm starting to think that this is a problem space where people don't typically seek useful approximations
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@jon_valdes my hope was that the moon's position relative to the earth would be the one situation where geocentrism still holds enough water for a useful approximation, but I'm starting to think that this is a problem space where people don't typically seek useful approximations
@aeva what I found is most methods for calculating these things are approximations that break down if you deviate from the year 2000 by more than 5 millenia or something. It just depends on what you consider a "useful" approximation
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@aeva what I found is most methods for calculating these things are approximations that break down if you deviate from the year 2000 by more than 5 millenia or something. It just depends on what you consider a "useful" approximation
@jon_valdes oh that's great. I figure for my use case it only has to be moderately accurate for the remainder of my lifespan however short or long that may be, and it's not really my problem if it accumulates a bit of drift after that
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@jon_valdes oh that's great. I figure for my use case it only has to be moderately accurate for the remainder of my lifespan however short or long that may be, and it's not really my problem if it accumulates a bit of drift after that
@aeva perhaps the easiest way would be to look at how other programs do it. I spent a bunch of time reading code for Stellarium, for example. Perhaps that, or a website like this could help you?
https://eyes.nasa.gov/apps/orrery/#/moon?time=2025-09-10T04:57:12.041+00:00 -
@aeva perhaps the easiest way would be to look at how other programs do it. I spent a bunch of time reading code for Stellarium, for example. Perhaps that, or a website like this could help you?
https://eyes.nasa.gov/apps/orrery/#/moon?time=2025-09-10T04:57:12.041+00:00@jon_valdes i found this a few hours ago http://www.geoastro.de/elevazmoon/basics/index.htm haven't had a chance to look at it in detail but it looked promising at first skim
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@jon_valdes i found this a few hours ago http://www.geoastro.de/elevazmoon/basics/index.htm haven't had a chance to look at it in detail but it looked promising at first skim
@aeva @jon_valdes I'm trying to remember what program we use to generate location accurate star charts in Avatar and Division... Maybe it can do the moon as well, will look it up later.
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@aeva @jon_valdes I'm trying to remember what program we use to generate location accurate star charts in Avatar and Division... Maybe it can do the moon as well, will look it up later.
@aeva @jon_valdes alright I think we just use data from sdss and reproject it for alpha centuri, blindly extrapolating for the correct date using the star velocity. so no complex orbital mechanics. However for the planetary bodies in solar system we use code derived from https://stjarnhimlen.se/comp/ppcomp.html
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@aeva @jon_valdes alright I think we just use data from sdss and reproject it for alpha centuri, blindly extrapolating for the correct date using the star velocity. so no complex orbital mechanics. However for the planetary bodies in solar system we use code derived from https://stjarnhimlen.se/comp/ppcomp.html
Word of caution about calculating these things on the GPU: implementations of trigonometric functions on the GPU are less accurate than you'd hope, and if you calculate a bunch of sin() and cos() for your view direction per pixel, they turn out not to be accurate enough for stable movement across a 60° fov on a 4K screen. Particularly Intel, which seems to barely pass the D3D precision requirements there...
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Word of caution about calculating these things on the GPU: implementations of trigonometric functions on the GPU are less accurate than you'd hope, and if you calculate a bunch of sin() and cos() for your view direction per pixel, they turn out not to be accurate enough for stable movement across a 60° fov on a 4K screen. Particularly Intel, which seems to barely pass the D3D precision requirements there...
@jon_valdes @aeva right, yeah I should also mention all that is done on the cpu, and with double precision. I'm not really sure if you can even squeeze it to work with f32.
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@jon_valdes @aeva right, yeah I should also mention all that is done on the cpu, and with double precision. I'm not really sure if you can even squeeze it to work with f32.
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@jon_valdes @dotstdy blessedly I'm planning on doing this on the cpu, but
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@jon_valdes @dotstdy blessedly I'm planning on doing this on the cpu, but
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@jon_valdes @dotstdy my laptop has a recent-ish Xe gpu
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@jon_valdes @dotstdy my laptop has a recent-ish Xe gpu
@jon_valdes @dotstdy it's bizarre seeing my 10 year old telephone's mali do better at... anything at all
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@jon_valdes @dotstdy it's bizarre seeing my 10 year old telephone's mali do better at... anything at all
@jon_valdes @dotstdy though I guess the corner the intel case is cutting is where the slope starts to level out so I guess that makes sense. are CPU trig functions just as bad?
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@jon_valdes @dotstdy though I guess the corner the intel case is cutting is where the slope starts to level out so I guess that makes sense. are CPU trig functions just as bad?
@jon_valdes @dotstdy would mollytime get a warmer, fuller sound if i switched to expensive software sine waves :3
Gli ultimi otto messaggi ricevuti dalla Federazione
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now that I'm a bit further down this rabbit hole I'm realizing this isn't much different from the terrestrial cartography I did one summer in college about 16 years ago, except that your benchmarks are all moving a lot faster
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@ok That's what I thought.
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Bot server is here: https://github.com/evanp/activitypub-bot and you can ask @ok if they are OK
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The update was hard; the jsonld.js library was choking on the FEP's context document because Codeberg Pages, where FEP context documents are hosted, is unreliable.
I ended up adding a feature to the `activitystrea.ms` NodeJS library to let you pre-cache a context document, so it didn't have to go fetch it at run time. While I was under the hood, I also fixed a couple of bugs that made it hard to work with extra context documents.
The bot server is now working; I'm going to add more contexts.
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I updated the #ActivityPubBot server software to use FEP-5711, the inverse properties FEP. It is a way to declare two-way relations; if X has an `inbox` property with value Y, then Y has an `inboxOf` property with value X. It helps with navigation when you're using the ActivityPub API, and it also helps with spoofing (since both objects agree on the relationship).
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@lkngrrr are you on the plane right now?
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I know I am flying Air France to Paris in an Airbus 350 but WOW I was not prepared for how French this was gonna be
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Contro il ponte, contro la repressione! Solidarietà agli arrestati No Ponte (con gli indirizzi per scrivere ai compagni e indicazioni per il sostegno economico)
@anarchia
Riceviamo e diffondiamo: CONTRO IL PONTE, CONTRO LA REPRESSIONE SOLIDARIETÀ AD ANDRE, BAK E GUI Negli scorsi giorni trehttps://www.rivoluzioneanarchica.it/contro-il-ponte-contro-la-repressione-solidarieta-agli-arrestati-no-ponte-con-gli-indirizzi-per-scrivere-ai-compagni-e-indicazioni-per-il-sostegno-economico/
