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> IWA?
<galois> IWA: Inner Working Angle
<egg|laptop|egg> UmbralRaptop: my concern wrt FoV is that if we say bandwidth is what limits imaging that’s far from the diffraction limit, limiting the resolution is only one option ; you could also choose to limit the FoV, and both are things you could change in-flight provided the sensor is dense enough
<egg|laptop|egg> so if we don’t model the sensor at all, a wide FoV instrument is usable as a narrow FoV instrument of the same aperture, which seems very wrong
* raptop eyes WFC2's variable resolution silliness
<raptop> er, WFPC2
<egg|laptop|egg> raptop: basically, what prevents someone from putting a fancy sensor on Kepler and using it like a larger-than-SST optical space telescope
<egg|laptop|egg> (for deep sky work that is)
<raptop> SST?
<galois> SST: Spitzer Space Telescope
<SnoopJ> superconducting supercolliding tunnel
<raptop> [in this channel, we do not acknowledge the Boeing 2707?)
<raptop> s/\?)/]/
<egg|laptop|egg> I mean admittedly they do that to an extent on Kepler, they downlink only part of the field of view
* raptop wants to say that variable field of view with a telescope requires some additional optics
<egg|laptop|egg> yeah if you want to vary the FoV
<raptop> ignoring postage stamps vs full frame images
<egg|laptop|egg> but if you have a wide FoV (hence the example of Kepler), you can have a postage stamp
<egg|laptop|egg> and even if you have a very dense sensor, you still have a lot of aperture so the diffraction limit is the same ?
<egg|laptop|egg> ah but the light gathering capability is reduced
<raptop> yeah, though smol pixels are noisy (and you can't get faint objects)
<egg|laptop|egg> right and there is a limit to the smolness of pixels too
<egg|laptop|egg> (though is it relevant or is it past the diffraction limit in practice)
<egg|laptop|egg> (also, how would it be modeled if I have only aperture and FoV to work with >_>)
<raptop> something about image scale or plate scale?
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<egg|laptop|egg> raptop: what does that mean eggsactly
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<raptop> egg|anbo|egg_: Maybe I'm misremembering the terms, but thinking about the angular resolution and linear size at the image plane
<raptop> Hrm, we'd ned to have a focal length
<egg|cell|egg> Yeah
<raptop> so many eggs
<egg|cell|egg> NUNUZ MEŠ
<SnoopJ> !how many 卵
<galois> SnoopJ: 360 卵s
<SnoopJ> no scope
<raptop> More eggs than an FPGA class
<whitequark> oof
<egg|cell|egg> Egg Œuf Uovo Ei Яйцо 𒉭 蛋 卵...
* egg|cell|egg pets whitequark
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<raptop> !wpn
* galois gives raptop a plotter
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<galois> title: DSN Resources for Students | NASA
<raptop> "records show you many not have purchased your textbooks"
<raptop> 1) No
<raptop> 2) Libgen
* raptop looks at the CDC deathtoll figures
<raptop> Oh, hey, we broke 405k today
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<egg|anbo|egg> raptop: is there a correlation between aperture size and sensor size in practice
<raptop> I want to say yes
<egg|anbo|egg> admittedly weak statement
<raptop> But, you can fiddle with focal length, etc which gets some variations
<egg|anbo|egg> hmm
* raptop pokes iximeow, since I'm pretty sure that they have practical knowledge of this. especially for a 20 cm scope
<egg|anbo|egg> why do the larger deep sky scopes use so little of their focal plane
<egg|anbo|egg> (HST, JWST, etc.)
<egg|anbo|egg> (insert obligatory remark about how JWST uses none of its focal plane)
<iximeow> lmao
<raptop> lolsob
<raptop> I would assume something about abberations and vignetting
<iximeow> i'm not sure about particularly large instruments but through the ones i'm familiar with it seems like the answer is yes?
<raptop> Hrm, HST's instruments are old
<raptop> WFC3 was installed in what, 2011?
<egg|anbo|egg> that’s not that old
<egg|anbo|egg> (2009)
<raptop> I'm wondering how much detectors have grown with a decade of development
<egg|anbo|egg> also huh, STS was still around in 2009 ?
<iximeow> yeah abberations get really annoying the further off-axis you get. again not sure how that changes with aperture size but another consideration is that there aren't many huge ccd/cmos slabs
<raptop> Though I guess SDSS's was huge
<egg|anbo|egg> yeah Kepler also very much uses all of its focal plane
<iximeow> ah SDSS is the name i was looking for. i was curious if there's any good writing about that design
<egg|anbo|egg> (and re. iximeow’s point, the sensor is curved on Kepler)
<raptop> Yeah, max size (pix) has slowly grown over time, so wide field instruments tend to be these arrays (which leads to regular gaps in the images that need drizzling and processing)
<iximeow> i assume until relatively recently that packing a bunch of sensors next to each other isn't easy to do
<raptop> egg|anbo|egg: yeah, that also happens. A lot of glass plates were also curved
<raptop> In the bad old days, there were CCDs that like 256x256
<raptop> (especially in the 80s. Might have had a 2-digit number of pixels on one axis in some cases?)
<egg|anbo|egg> I mean, sure, see also VIIRS’s 48-pixel sensor (which then sweeps 6400×480) but if you have a thing like HST you try to go to the limits of what you can do unless other factors get in the way
<egg|anbo|egg> (as we have seen, for VIIRS, that’s bandwidth)
<egg|anbo|egg> admittedly for Kepler bandwidth is a concern too since they bin/preprocess/sample their gigantic sensor onboard
<galois> title: SDSS Instruments
<galois> Unexpected error (HTTPSConnectionPool(host='www.sdss.org', port=443): Max retries exceeded with url: /instruments/camera/ (Caused by SSLError(SSLError(1, '[SSL: WRONG_SIGNATURE_TYPE] wrong signature type (_ssl.c:1108)')))) from raptop at 2021-01-22 18:11:58.139473. Message was: ah, more details https://www.sdss.org/instruments/camera/
* iximeow would simply expect the error
<raptop> EXPECTED ITEM IN BAGGING AREA
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