egg|nomz|egg 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.
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<Raptop>
"unfortunately, the monster can be shown to eggsist" bofh^28, probably
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<bofh^28>
Raptop: I feel like I typed that eggsact phrase at some point.
<bofh^28>
well either me or egg
<egg>
that sounds more like something you'd type
<egg>
I don't think i find the monster's eggsistence unfortunate
<egg>
bofh^28: okay i want to poke at the approximation thing but i confused myself
<kmath>
<stephentyrone> @eggleroy @bofh453 Specifically, if x0 has relative error e, x0*x0*y is bounded by something like 1 ± 2e. So, we wa… https://t.co/5fu2t9bY6b
<egg>
bofh^28: I don't know how to minimax,
<bofh^28>
I have absolutely no idea how to apply it to a *polynomial* like that. Remez exchange?
<bofh^28>
Like I'd need to think about this myself b/c I genuinely haven't the foggiest either.
<bofh^28>
are you fucking shitting me
<bofh^28>
I downloaded a scan of Buchberger & Möller
<bofh^28>
IT'S A SHITTY SCAN, LIKE SIDEWAYS AND PART OF ONE PAGE IS OVERLAPPING
<SilverFox>
F
<SilverFox>
python sucks
<SilverFox>
trying to do all this opencv stuff and I'm trying to download the pre-requisites and it's just a hassle
<bofh^28>
"Dawn missed scheduled communications sessions with NASA's Deep Space Network on Wednesday, Oct. 31, and Thursday, Nov. 1. After the flight team eliminated other possible causes for the missed communications, mission managers concluded that the spacecraft finally ran out of hydrazine, the fuel that enables the spacecraft to control its pointing."
<bofh^28>
F
<SnoopJeDi>
oh :(
<SnoopJeDi>
bofh^28, hmm, is hydrazine only strictly necessary when you're out in the far reaches, or is that standard for probes at all distances?
<SnoopJeDi>
I did our bike wheel gyroscope demo last weekend and I have a small "bit" about this, mostly in the context of space telescopes, but I do mention gyros in other spacecraft
<bofh^28>
SnoopJeDi: so I think it's critical for most S/C pointing and attitude control
<bofh^28>
I don't know how Dawn's gyros & reaction wheels worked so I can't say for certain
<bofh^28>
also wow I like how near-simultaneously I get 5 different twitter posts on Dawn.
<SnoopJeDi>
I know broadly that gyro/rw are pretty good until you need *high* precision pointing
<SnoopJeDi>
so it's understandable that anything relying on DSN would be at the mercy of hydrazine, but it's got me wondering now...
<bofh^28>
I mean part of the issue with Dawn is it's solar-powered and fairly far from the sun.
<SnoopJeDi>
"the issue" meaning "you could maybe do this with reaction wheels if you had the go-go juice?"
<UmbralRaptop>
At some point you'd saturate the wheels.
<bofh^28>
Well more like "the failure case is much worse"
<SnoopJeDi>
yea I guess I should have said gyros/rws, since I doubt you can do much with rw for this kind of pointing?
<bofh^28>
since with an RTG-powered craft you can in theory just wait until you coincidentally come within pointing.
<SnoopJeDi>
aaaAAAAAA
<bofh^28>
since you only care about antenna pointing error, not (antenna pointing error, slrpnl pointing error)
<bofh^28>
(with apologies to birdemic)
<UmbralRaptop>
Apparently they had already lost some RWs
<SnoopJeDi>
ahhh
<egg>
birdemic?
<egg>
also eventually reaction wheels saturate if something perturbs your spacecraft in a spinny way
<SnoopJeDi>
as an aside, I'm really glad NASA/NSF are a *LOT* friendlier to reaction wheels on cubesats these days
<bofh^28>
birdemic is a terrible movie about.... evil birds and stock options
<bofh^28>
or something.
<SnoopJeDi>
they were downright "lol no" about it when I was an undergrad, despite AAUSat2 having done it already and at least partially succeeded in detumbling
<SnoopJeDi>
it's pretty terrible, I would not recommend watching it without rifftrax
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* egg
meows at bofh^28
<UmbralRaptor>
Yay, Urvogel still works.
* UmbralRaptor
pokes IRC with a stick.
<UmbralRaptor>
!meow
* Qboid
meows at
<egg>
<UmbralRaptor> Yay, Urvogel still works. <<< kozai!
* UmbralRaptor
should try to revive Keldysh and/or wander off with the surplus boxen.
<UmbralRaptor>
They have various i5s and i7s.
<egg>
UmbralRaptor: at least you have sse2 i guess
<UmbralRaptor>
egg: Principia doesn't compile on 32bit machines. >_>
<egg>
UmbralRaptor: i know
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<bofh^28>
Urvogel?
<UmbralRaptor>
bofh^28: Old scavenged raptop that I stuck Debian on.
<bofh^28>
I mean I think there is one particular cursed line of Prescotts that has SSE2 but not 64-bit support.
* egg
meows at whitequark
<bofh^28>
But, like, Prescott.
<egg>
!wpn whitequark
* Qboid
gives whitequark a keen review with a trihexaflexagon attachment
<UmbralRaptor>
It's a Core1Duo with a "Designed for XP" sticker on it.
<bofh^28>
I misread that as "CorelDuo"
<UmbralRaptor>
erk
* egg
meows at bofh^28
<SnoopJeDi>
CorelDuo: just when you thought it was safe to get back into image editing
<UmbralRaptor>
Incidentally, I'm 80% certain that our fancy 'cluster' is a bunch of Core2s in a trenchcoat.
<SnoopJeDi>
isn't that what a Xeon is
<UmbralRaptor>
Depends on the Xeon?
* UmbralRaptor
thought that "Xenon" simply meant server, so you could find anything from like a Pentium 3 to whatever the current i9 is with that name.
<UmbralRaptor>
*Xeon
<UmbralRaptor>
Hopefully bofh^28 et al. can see why I would tyop that.
<bofh^28>
I mean I ALSO used to think that "Xeon" simply meant "server-grade", lol.
<bofh^28>
Also yes, see typical ion propellant.
<UmbralRaptor>
Compute-Thermal Rocket
<SnoopJeDi>
I don't know very much about the Xeon architecture except "lots of cores vroom vroom"
<SnoopJeDi>
which reminds me, I'm supposed to check if this server is turboboosting
<UmbralRaptor>
Something something 8 physical cores per node I think.
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<egg>
!meow UmbralRaptop
* Qboid
meows at UmbralRaptop
<egg>
!wpn whitequark
* Qboid
gives whitequark a polynomial submersion/lake hybrid
<egg>
!meow whitequark
* Qboid
meows at whitequark
* UmbralRaptop
caws at egg
<SnoopJeDi>
UmbralRaptop, I think the number of physical cores varies, this new server has 18 per socket, I think
<SnoopJeDi>
hah, I haven't looked at /proc/cpuinfo on a machine since meltdown/spectre: `bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass`
<SnoopJeDi>
but there's lot of other arch stuff that matters quite a lot to People Smarter Than Me AFAIK
<SnoopJeDi>
something something memory something caching something communication
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<SnoopJeDi>
PI of the Fermi GBM gave today's colloquium, mostly on multimessenger GRB stuff. structured jets seem really neat and I guess shock breakout is cool too although she made it sound like a pretty heavily disfavored model atm
<SnoopJeDi>
but also talked about "uhhh so the Crab nebula does *not* have constant hard x-ray flux, so we should probably not calibrate against it anymore"
<SnoopJeDi>
("crab units" is an adorable name)
<egg>
bofh^28: meow
<UmbralRaptor>
inconstant crab units?
<UmbralRaptor>
(aaaaaaaaa!)
<BPlayer>
Was just posted on a forum I frequent: "A friend of mine in college spilled Methylene Chloride onto her TI Nspire."