Alistair wrote: > > Hello, > > Let me introduce myself. I'm a student working on my Master's in > Applied Physics. My thesis is on Daylight Detection of LEO Satellites > in Infrared. > > I'm curious as to information about some of the daylight Iridium flares > that have been mentioned on some websites. I've read the background on > most of these sites. What I"m really looking for is information on sky > brightness, wavelengths and local sunset/sunrise times. > > More generally, if anyone has some knowledge on non-Iridium flare > imaging of satellites in or near daylight conditions, that would be > greatly appreciated. I'm surprised that nobody's replied to this message, at least not publicly. IR observing of satellites in daylight is something I've been wondering about for a while. I have vague recollections of rather speculative stuff about the US Air Force systems to do this which were sort of confirmed by the picture of the Columbia which seemed to have been taken, IIRC, at about 11am local time from Hawaii. Can't remember if that was explicitly stated to be IR or if it was just my assumption. During the day, the sky is blue - something which might be news to the more nocturnal members of this list. Red light doesn't get scattered much. Presumably, near IR gets scattered even less. The following is hearsay - but I got it from a pretty reliable source. Webcams are quite sensitive in at least some IR. If you remove the manufacturer's lens to do, say, prime focus imaging with a telescope, then you have to extract the IR filter from the original lens and refit it somehow - otherwise the IR light which is out of focus blurs the image. The same source also told me that exposed colour film can be used as an IR filter. Therefore, it should be quite cheap and straightforward to look at the daylight sky in IR to see what can be seen. I need to find out a bit more about IR filters and IR transmission through the atmosphere first. It's on my to-do list, but quite a way down. Has anybody else tried this sort of thing? Ed. ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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