UmbralRaptor 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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<egg|laptop|egg> raptop: hm, given that KSP can’t really model attitude concerns wrt imaging pointing, how much does FoV matter
<egg|laptop|egg> I feel like it should, somehow, but I have trouble figuring out how
<egg|laptop|egg> it clearly does for pushbroom width so there’s that
<egg|laptop|egg> I guess you have to force planetary surface imagers to point to the nadir?
<raptop> egg|laptop|egg: more in a "we assume that pointing is handled correctly, but some missions have defactor or actual FoV requirements"
<raptop> eg: if you want full frame images of a planet, there's a minimum distance
<egg|laptop|egg> yeah
<raptop> Also smol FoV for a survey means it takes longer
<egg|laptop|egg> raptop: but if pointing is abstracted away too much, you can take full-frame images of Earth with an HST-like in LEO, by spinning it to scan,
<raptop> This is also a way to backdoor in how really large FoVs often require doing weird things to the optics, so you might get low effective aperture, or high costs
<egg|laptop|egg> s/LEO/GEO/ the horizon is a thing
<galois> egg|laptop|egg meant to say: raptop: but if pointing is abstracted away too much, you can take full-frame images of Earth with an HST-like in GEO, by spinning it to scan,
<raptop> Ah, guess the options require more abstracting than I thought?
<egg|laptop|egg> basically, a narrow FoV is a wide FoV if you allow for truly arbitrary shenanigans with attitude
<egg|laptop|egg> see SEVIRI, which does full-disk GEO by literally being on a spinning sat
<raptop> attitude and time!
<egg|laptop|egg> true
<raptop> Also see WFSE, which did all-sky surveys by spinning and waiting for Earth to move about its orbit
<raptop> *WISE
<raptop> IITC
<raptop> *IIRC
* raptop stabs fingers
<egg|laptop|egg> right, but I think scanning by orbital motion and scanning by actually moving the spacecraft or bits thereof should be seen differently
<egg|laptop|egg> I would imagine the correct abstraction for a SEVIRI-like instrument is that it has a wide FoV, since the spin-scannability is baked into its design
<egg|laptop|egg> and then you would actually forbid doing that with an HST probably
<egg|laptop|egg> which means, since you cannot model attitude, that everything that images a surface points towards the body centre?
<egg|laptop|egg> and then if you point HST towards Earth your swath is minuscule unless you are very very far
<raptop> hm
<egg|laptop|egg> !u ≪
<galois> ≪: U+226a MUCH LESS-THAN
<raptop> Important birb reminder http://www.birdandmoon.com/comic/raven-vs-crow/
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<egg|laptop|egg> !u x
<galois> x: U+0078 LATIN SMALL LETTER X
<egg|laptop|egg> !u —
<galois> —: U+2014 EM DASH
<X> O_o
<X> !u egg
<galois> e: U+0065 LATIN SMALL LETTER E
<galois> g: U+0067 LATIN SMALL LETTER G
<galois> g: U+0067 LATIN SMALL LETTER G
<egg|laptop|egg> raptop: https://github.com/Kerbalism/KerbalismContracts/wiki/Design#imagers thoughts on the formulæ, and in particular the TODOs therein?
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<raptop> The todo totally gives you an eggscuse to use Janskys
<raptop> And yeah, if we care about UV vs visible vs IR, we need the different quantities
<raptop> ...oh, irradiance as in reflected sunlight
<raptop> oh no
<raptop> This means we need to consider geometric and/or bond albedo
<raptop> I'll need some clarification on the irradiance, because I'm unclear on that πd²/4
<raptop> Resolution stuff seems good
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<egg|laptop|egg> raptop: the πd²/4 is just the area of the telescope aperture
<egg|laptop|egg> (the assumption being that all the energy that gets into the telescope reaches the detector
<egg|laptop|egg> )
<raptop> Ah
<egg|laptop|egg> raptop: but mostly the questions are: what is the energy that the CCD needs to detect a thing?
<raptop> That varies weirdly with the type of instrument from "eh, close enough" to "laughably wrong"
<egg|laptop|egg> hah
<raptop> Uh, depends somewhat on the CCD, but in some cases it's "one photon"
<egg|laptop|egg> right, to detect
<egg|laptop|egg> but well, here to meaningfully observe
<raptop> Like, directly imaging on a system with few optical elements is close enough. But polarimetry or high resolution spectroscopy (especially EPRV shenanigans)...
<egg|laptop|egg> e.g. say you have a sky survey that goes to nth magnitude, what energy do you get from an nth magnitude star on the surveying instrument
<egg|laptop|egg> also, re. resolution, how does that work when not diffraction limited
<egg|laptop|egg> limited by sensor resolution I suppose? what is a sane value for that?
<raptop> Yeah, and I'd have to run some numbers/double check, respectively
<raptop> (re resolution)
<raptop> For what counts as a detection, typically some SNR. I, er, would want to skim a few data release documents (SDSS, 2MASS, IRAS, WISE, whatever) for typical values
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<egg|cell|egg> Meow
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<kmath> <bsgaudi> ps. I've been told that we shouldn't use acronyms. It's the Roman Space Telescope or just Roman for short. You know, kinda like Madonna.
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<_whitenotifier-d13c> [Principia] pleroy closed issue #2583: The flight plan should surface unexpected statuses - https://git.io/Jfz8L
<_whitenotifier-d13c> [Principia] pleroy pushed 12 commits to master [+6/-6/±45] https://git.io/Jfaq2
<_whitenotifier-d13c> [Principia] pleroy e1f3731 - Generated files before the change.
<_whitenotifier-d13c> [Principia] pleroy 847787a - Journal and C# changes.
<_whitenotifier-d13c> [Principia] pleroy 7957b14 - Const the returned pointers.
<_whitenotifier-d13c> [Principia] ... and 9 more commits.
<_whitenotifier-d13c> [Principia] pleroy opened pull request #2589: Use the Status message in the exceptions returned from the external interface - https://git.io/Jfaq5
<_whitenotifier-d13c> [Principia] Pending. Build queued… - 
<_whitenotifier-d13c> [Principia] Pending. Building… - http://casanova.westeurope.cloudapp.azure.com:8080/job/Principia/4309/
<_whitenotifier-d13c> [Principia] Success. Build finished. - http://casanova.westeurope.cloudapp.azure.com:8080/job/Principia/4309/
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<egg|laptop|egg> UmbralRaptop: telling astronomers to not use acronyms is definitely going to work,
<egg|laptop|egg> UmbralRaptop: > typically some SNR.
<egg|laptop|egg> hmm.
<egg|laptop|egg> do we need to model the noise then?
<egg|laptop|egg> I suppose probably, what with IR telescope cooling)
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<_whitenotifier-d13c> [Compatibility] Success. #752 succeeded - https://dev.azure.com/mockingbirdnest/445d7b9d-0318-42e3-857f-b69d40b1ed1b/_build/results?buildId=752
<_whitenotifier-d13c> [Principia] pleroy pushed 1 commit to master [+0/-0/±1] https://git.io/Jfa8Q
<_whitenotifier-d13c> [Principia] pleroy 04dc6ef - Remove a trailing space.
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<WeylandsWings> egg telling anyone in the space business to not use acronyms isnt going to work
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<_whitenotifier-d13c> [Principia] pleroy pushed 1 commit to master [+0/-0/±1] https://git.io/JfaR0
<_whitenotifier-d13c> [Principia] pleroy dd92644 - Document the build process for Linux and macOS Fix #2580.
<_whitenotifier-d13c> [Principia] pleroy closed issue #2580: Please add build instructions for linux - https://git.io/JfErh
<_whitenotifier-d13c> [Principia] pleroy pushed 1 commit to master [+0/-0/±1] https://git.io/JfaRi
<_whitenotifier-d13c> [Principia] pleroy adac651 - Mention zfp.
<egg|laptop|egg> !wpn whitequark
* galois gives whitequark a clockwise culverin
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* egg|laptop|egg meows at UmbralRaptop
<_whitenotifier-d13c> [Principia] gert7 opened issue #2590: Vessels teleport/switch places upon EVA - https://git.io/Jfaz1
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<raptop> !wpn egg|laptop|egg
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<egg|laptop|egg> raptop: how do i into snr
<raptop> Ideal world version would be something like sqrt(photons), uh checking how I did it with instrument noise
<raptop> I_0[λ][3] = I_0[λ][2]/pix*gain / np.sqrt(I_0[λ][2]/pix*gain + (gain*read_noise*2.2*2*n_ex pose)**2 + (gain*dark_current*exptime)**2)
<raptop> uh, this makes some unrelated speggtrograph, CCD well depth, and fudge factor assumptions
<raptop> We probably don't need to consider how read noise makes co-adds less effective than they should be?
<raptop> Ah, more generally signal / sqrt(sum of various noise sources)
<raptop> poisson noise means that signal shows up under the square root (so even with a perfect detector, SNR is signal/sqrt(signal) or just sqrt(signal))
<raptop> the noise sources (I have read and dark current) get added in quadrature
<raptop> I'm missing sky noise there because it's assuming vaguely bright stars
<raptop> This is not safe for sufficiently faint point sources, eggstended objects, and areas with lots of sky glow (which may mean zodical light)
<raptop> hrm
* raptop opens several teggstbook pdfs to check
<raptop> Incidentally, I'll be amused if this ends up including the Planck function somewhere for getting detection requirements in various wavelength ranges for self-luminous bodies
<egg|laptop|egg> raptop: hm
<egg|laptop|egg> so, a lot of those things we ought likely make constant (any CCD properties, we don’t want to model that)
<egg|laptop|egg> the one variable that I can think of is temperature which we might be able to model somewhat ?
<egg|laptop|egg> (and which determines mission constraints)
<raptop> rabbit hole suggestion: vaguely model those properties, with lower noise and higher resolution options available at later dates
<raptop> But it's entirely possible that we'd want to skip that, and do sqrt(photons)
<raptop> So detector temperature would just be "you must be this cool to observe that wavelength"?
<raptop> Also, I like how you did bolometric magnitudes to avoid having to choose between AB, Vega, and more exotic systems
<egg|laptop|egg> should temperature really work as a hard threshold, or should a warmer instrument work at a degraded sensitivity
<egg|laptop|egg> raptop: yes I started looking at magnitudes, screamed, and then used the IAU resolution
<egg|laptop|egg> the IAU resolution will be with you, always
<raptop> Depends on how much we're simulating eg: cooling
<raptop> note to self: borrow チルノ so you don't need to mess around with helium tanks or hydrogen ice
<SnoopJeDi> raptop, TIL 「ドストライク」
<SnoopJeDi> neat little idiom
<raptop> SnoopJeDi: oh?
<SnoopJeDi> I saw it in a tweet where I think it was used in the "this is exactly my kind of thing" sense
<SnoopJeDi> it was ドストライクな there
<SnoopJeDi> vocab of the rest of it was ofc a bit beyond me but I happened to check out the katakana
<SnoopJeDi> MS translate does predictably poorly with it and turned it into "dstrike"
<kmath> <akebi_rat> やねうらっとさん、ドストライクな子来るたび♀表記で泣く(♂♀飼う余裕が無い)
<raptop> Google translate also says "do strike"
<SnoopJeDi> lol
<SnoopJeDi> I think you could also spell it どストライク
<SnoopJeDi> the どis 'just' a modifier there I guess
<SnoopJeDi> (this is based on poking at it in jisho)
<raptop> !c 206265/3600
<galois> raptop: 57.29583333
<raptop> !c 206265/3600*3.14159/180
<galois> raptop: 1.000000095
<raptop> Ah, magic numbers
<UmbralRaptop> The ice cream truck is back
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<_whitenotifier-d13c> [Principia] pleroy commented on issue #2590: Vessels teleport/switch places upon EVA - https://git.io/JfaVs
<kmath> <DACIWEI1991> love citing "unpublished manuscripts" and "private communications" despite being very aware of plenty of publicatio… https://t.co/nYkKvLnO37
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<WeylandsWings> UmbralRaptop: that can be a good way of getting peoples name into the doc without giving them authorship
<raptop> hrm
* egg|laptop|egg meows at raptop