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
<egg|anbo|egg_>
raptop: hm, i have a magnitude which looks about right except it has the wrong sign,,
<raptop>
egg|anbo|egg_: it's totally possible that it needs one more or fewer negative signs. Or flipping a multiply/divide inside a log
<egg|anbo|egg_>
nah I think it is just a coincidence
<egg|anbo|egg_>
trying to derive a formula for limiting magnitude (wavelength, eggsposure time, sensor temperature, aperture) which might be questionable to start with
<egg|anbo|egg_>
and mostly having no idea what I am doing wrt noise
<egg|anbo|egg_>
raptop: what would happen if you, e.g., cryogenically cooled hubble
<egg|anbo|egg_>
would its limiting magnitude go up significantly? I guess not since nobody launches cryogenic visible/UV scopes?
<raptop>
egg|anbo|egg_: well, it would reduce noise, andeg: SDSS does use cryogens, but therman noise isn't a huge deal in optical
<egg|anbo|egg_>
oh
<raptop>
...I guess hubble counts as being fairly cooled since NICMOS
<egg|anbo|egg_>
what are the other sources of noise
<egg|anbo|egg_>
because I was modelling everything as being thermal
<egg|anbo|egg_>
OK my formula says Hubble would reach a limiting magnitude of 2120 if it were cooled to
<egg|anbo|egg_>
15 K
<egg|anbo|egg_>
in 30 s of eggsposure
<egg|anbo|egg_>
conclusion: it is probably not thermally limited,,,
<raptop>
radiation (ionizing), read noise, pixels varying in terms of sensitivity
<raptop>
IIRC
<egg|anbo|egg_>
hmm
<raptop>
also I recall seeing a paper on arxiv at one point about encoding causing noise for really faint objects
<raptop>
read noise is actually a big deal in some cases (source: staring at my simulations)
<egg|anbo|egg_>
right so those are ~handwave handwave~ a constant noise term wrt KC-relevant variables?
<egg|anbo|egg_>
i.e. mission-design-relevant variables
<raptop>
yeah, read noise can be dealt with by exposing longer. the radiation aspect (especially cosmic ray impacts) might be worth kinda-sorta modeling, since that gets people to avoid the van allen belts and jupiter's current sheet of painful death
<egg|anbo|egg_>
ah yes, good point
<egg|anbo|egg_>
... but how the hell do I find constants to plug in that model, since people ~do not observe where ionizing radiation is annoying
<raptop>
I don't know, call up teledyne or ball?
<raptop>
...
<raptop>
wait, would WeylandsWings be able to give a BOTE approximation?
<WeylandsWings>
for?
<egg|anbo|egg_>
noise in imaging coming from ionizing radiation
<egg|anbo|egg_>
BOTE?
<WeylandsWings>
back of the envelope
<WeylandsWings>
and no
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<UmbralRaptop>
blarg
<WeylandsWings>
Maybe look at the rate of Chip issues from radiation (but flips and latch ups and the like) and use that data for a ccd with a modifier as ccds are more fragile?
<egg|anbo|egg_>
hmmm now solving for the constants in my model gives noise that decreases with temperature
<WeylandsWings>
Which is good
<egg|anbo|egg_>
well, that would make things easier, yes
<galois>
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