raptop changed the topic of #kspacademia to: https://gist.github.com/pdn4kd/164b9b85435d87afbec0c3a7e69d3e6d | Dogs are cats. Spiders are cat interferometers. | Космизм сегодня! | Document well, for tomorrow you may get mauled by a ネコバス. | <UmbralRaptor> egg|nomz|egg: generally if your eyes are dewing over, that's not the weather. | <ferram4> I shall beat my problems to death with an engineer. | We can haz pdf
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<mofh>
egg|zzz|egg: it does seem to make sense to me, tho I'm not sure what justificiation I'd use here
<mofh>
but it seems reasonable to me, at the least.
<egg|zzz|egg>
mofh: the justification is that you want to eliminate short-period perturbations (those that recur every revolution), as they have a high amplitude and are by definition a distraction from the Keplerian behaviour and its evolution
<egg|zzz|egg>
so you filter over a duration that's ~one revolution, for some definition of revolution
<egg|zzz|egg>
the definition that is least affected by short-period oscillations ideally, so that you can start somewhere :-p
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<mofh>
egg|zzz|egg: hrm, that makes sense.
<mofh>
I keep forgetting short-period perturbations *recur*
<egg|zzz|egg>
mofh: even if they didn't, you'd call them "noise" instead of "short-period", and a low-pass filter would still work :-p
<egg|zzz|egg>
(but probably wouldn't work as well I guess)
<mofh>
point, I guess at that point they are noise, I don't know why I was worrying about the inability to predict non-recurring perturbations
<mofh>
unrelated but this hacking dry cough is AMAZING no actually it fucking sucks.
<mofh>
thanks, neutrophils.
<mofh>
theutrophils.
<whitequark>
lol
<mofh>
like the worst part is I know more adrenergics (specifically adrenergics) will help with the throat insanity or at least make it more tolerable but are a *terrible* idée to take in this weather
<mofh>
since vasoconstriction is just about the last thing I want right now
<egg|zzz|egg>
mofh: well, they ought to be highly periodic, which should make integration over something close to their period a decent filter
<egg|zzz|egg>
that's how you end up getting a good e by integrating e sin ω, e cos ω (that was over many periods but iirc mean ω varies slowly and only with long-period cyclic variations, no secular ones, for TOPEX/Poseidon so it still worked)
<egg|zzz|egg>
(even though osculating e is garbage at all times :-p)
<kmath>
<✔Tesco> @mattyjstock Hi Matthew, I have had a response from my support team. They have advised the date code on the relish… https://t.co/PkPpZIJUjW
<UmbralRaptop>
2020-05-20T00:00:00Z is JD 2458989.5
<kmath>
<jajohnson51> TIL that the artistic illustrations of the Milky Way make it look too blue. The Milky Way is probably a red spiral… https://t.co/9qjPf6XPkB
<SnoopJeDi>
I wonder what astrobiology has to say (if anything as yet) about the age of a galaxy and life formation. Presumably you need some pretty good mixing to occur before you've got enough for what they'd call "interesting" chemistry
<UmbralRaptop>
I'd guess that you want a complex star formation history. Lots early on for heavy elements, but then a moderate amount (small bursts?) later to exploit it without getting too many GRBs
<UmbralRaptop>
Don't ask me about black hole feedback >_<
<egg|zzz|egg>
mofh: oh this is interesting: Precise Analytical Computation of Frozen-Eccentricity, Low Earth Orbits in a Tesseral Potential
<egg|zzz|egg>
featuring capitán de fragata Martín Lara
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<uovo>
mofh: topicquotes
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<UmbralRaptop>
egg: which type of frozen orbit would have an event horizion in its future lightcone?
<mofh>
egg|work|egg: what are the differences in frozen orbit type?
<egg|work|egg>
mofh: at the critical inclination, the argument of periapsis is unconstrained, the inclination prevents its drift (you get oulitka orbits)
<egg|work|egg>
the eccentricity is unconstrained as well
<egg|work|egg>
mofh: otherwise, the frozen orbits need to have an argument of periapsis at 90 or 270 degrees; it is the frozen eccentricity (dependent on chosen inclination and semimajor axis) that freezes the orbit (usually the orbit is near-circular, but not always)
<egg|work|egg>
mofh: type I freezing is by J2; frozen orbits around the moon are type II always because J2 does not dominate there
<mofh>
so type II are just everything not type I?
<egg|work|egg>
mofh: well yes, in a sense
<egg|work|egg>
they are the ones that are frozen by omega being 90 or 270 instead of i being i_c
<egg|work|egg>
mofh: I think both types form a 2-parameter family
<egg|work|egg>
in the type I case, e and ω are free
<egg|work|egg>
wait no a is free too
<egg|work|egg>
mofh: okay so type I is a 3-parameter family (ignoring the mostly-trivial freedom in Ω and initial M, can't really call those different orbits)
<egg|work|egg>
with i constrained to a mostly-fixed value (actually a function of a iirc but not that strongly)
<egg|work|egg>
mofh: whereas type II is a 2-parameter family, as you get e(a, i) (occasionally multivalued), and ω is ±90° (I think its sign is constrained by i too)
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<egg|work|egg>
mofh: meow
<egg|work|egg>
!wpn mofh, UmbralRaptop, whitequark, et al.
* galois
gives mofh, UmbralRaptop, whitequark, et al. a heptapodial tetrahedron
<UmbralRaptop>
Alien geometry?
<UmbralRaptop>
!wpn egg|work|egg
* galois
gives egg|work|egg a discrete ordinary hexagon
<mofh>
!wpn egg|work|egg
* galois
gives egg|work|egg a arsenic iridium square
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<mofh>
egg|work|egg: today's terrible hiding-from-the-canicule strategy: pavillion d'horloge, niveau -1, Pavillion Sully, Le Louvre :p
<mofh>
(and by terrible I mean it's actually *really* pleasant down here)
<mofh>
egg|work|egg: scrolling up,I
<mofh>
egg|work|egg: scrolling up, I'm a bit confused why frozen-by-J2 is the 3-parameter family, it strikes me as that's the one that should have *less* degrees of freedom but it's not
<kmath>
<MeteoMontsouris> Courage, la température baisse plus vite ce soir qu'hier soir… https://t.co/4WMdPrEzXT
<mofh>
more of a breeze tonight too, mercifully
<B787_300>
mofh: why is it important that the temp is falling faster
<B787_300>
actually let me ask the better question... how many times in the past decade has that location seem temps above 32.5
<mofh>
B787_300: uhm: A) not much of a climatological purpose, but it goes a long way into making it more livable, the temp didn't drop to livable levels until LATE last night and that didn't help, B) uhh very rarely?
<mofh>
like I think we're forecast for a high ~2degC warmer than the record for tomorrow or Friday, not sure which.
<B787_300>
and because its europe yall dont believe in AC
<B787_300>
(tbf i dont think 34C is all that hot
<B787_300>
like it will be 32.2 C high tomorrow where i am
<whitequark>
B787_300: "34C is hot/not hot" is a meaningless statement
<whitequark>
"34C with 85% humidity" is death
<whitequark>
"34C with 30% humidity" is pleasant
<B787_300>
fair point
<B787_300>
looks like when we hit 32.2 C tomorrow RH will be around 50%
<kmath>
<MeteoMontsouris> À 18 h, il fait 34.2 °C, légère brise, humidité à 53%, pas de pluie. https://t.co/I6zc33hmlI
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<uovo>
mofh: well, frozen-by-j2 is just "be in that plane", and you can have whichever orbit shape, size and orientation you want because ω' is 0 in that plane
<_whitenotifier-5dfc>
[Principia] eggrobin opened issue #2222: Flight plan error message wording - https://git.io/fjrxS