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Forum » SpaceEngine » Off-topic Discussions » Totally off-topic thread (Talk about anything.)
Totally off-topic thread
werdnaforeverDate: Monday, 11.08.2014, 01:13 | Message # 2506
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Quote Crashman1390 ()
Ooh, that a really low blow

Yes, "a low blow" was indeed what happened on 9/11.

EDIT:


Edited by werdnaforever - Monday, 11.08.2014, 01:24
 
DoctorOfSpaceDate: Tuesday, 12.08.2014, 08:30 | Message # 2507
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cry

Not one for celebrity deaths, but this sucks. Such a big part of my movie going experience while growing up.





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WatsisnameDate: Tuesday, 12.08.2014, 09:34 | Message # 2508
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Didn't know he had died until I noticed the "- 2014" in the caption and did a double-take. Suicide, apparently?

sad





 
DoctorOfSpaceDate: Tuesday, 12.08.2014, 09:55 | Message # 2509
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Quote Watsisname ()
Suicide, apparently?


Apparently so. The fact that after his next few movies come out there won't be anymore Robin Williams again is just a depressing thought.





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midtskogenDate: Tuesday, 12.08.2014, 19:41 | Message # 2510
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I'm looking through stuff from my meteor cams. This is obviously a satellite:


Video

But it flashes twice. Two panels on the satellite? It might not be uncommon, but I don't think I've seen twin flashes before.

Added: It reappeared the next night, 18 minutes later:





NIL DIFFICILE VOLENTI


Edited by midtskogen - Tuesday, 12.08.2014, 19:54
 
WatsisnameDate: Tuesday, 12.08.2014, 23:25 | Message # 2511
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Quote midtskogen ()
But it flashes twice. Two panels on the satellite? It might not be uncommon, but I don't think I've seen twin flashes before.


Interesting. Definitely is a satellite, but do we know or can we figure out which one it is? There are a lot of tumbling/derelict ones up there which produce multiple flashes as a consequence of their rotation, but it is curious that this exhibits only two flashes in close proximity and on both appearances. It also seems like the whole streak is itself a flare, which would argue against it being a tumbler.





 
HarbingerDawnDate: Wednesday, 13.08.2014, 00:27 | Message # 2512
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Quote Watsisname ()
can we figure out which one it is?

heavens-above.com is your friend





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WwadlolDate: Wednesday, 13.08.2014, 00:37 | Message # 2513
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https://www.youtube.com/watch?v=F1CddzgVW14#t=540
Some guy made the longest timer in Minecraft. Also featuring Space Engine!
 
WatsisnameDate: Wednesday, 13.08.2014, 06:29 | Message # 2514
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Quote HarbingerDawn ()
heavens-above.com is your friend


Indeed, calsky.com and Orbitron as well. smile But I'd need date/time/location to have much chance of finding it. There are so many satellites up there.





 
midtskogenDate: Wednesday, 13.08.2014, 09:46 | Message # 2515
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I've seen tumbling satellites, but those flash repeatedly.

59.97056N 10.649639E 349 masl. 2014-07-21 23:30UTC for the first pass. 2014-07-22 23:48UTC for the second pass. Exact timings can be found in the videos (second video).

The camera is pointed SSW and has a 150 deg FOV diagonally.





NIL DIFFICILE VOLENTI


Edited by midtskogen - Wednesday, 13.08.2014, 10:42
 
WatsisnameDate: Wednesday, 13.08.2014, 10:33 | Message # 2516
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The best match for both passes is USA 224, which is a classified reconnaissance satellite.

Midtskogen, what is it you're hiding over there? smile





 
midtskogenDate: Wednesday, 13.08.2014, 10:44 | Message # 2517
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Quote Watsisname ()
Midtskogen, what is it you're hiding over there?

I'm flying to SF on Saturday. That would be the reason.





NIL DIFFICILE VOLENTI
 
spacerDate: Wednesday, 13.08.2014, 17:00 | Message # 2518
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Totally off-topic thread ohhh? ok i am an astronomy nerd! tongue umnik




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midtskogenDate: Wednesday, 13.08.2014, 18:14 | Message # 2519
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So how accurate is heavens above? Last night it predicted a -8.4 iridium (94) for me at 00:09:51UTC (az 173 alt 56), and sure enough it did appear on time (±1s):

Close up:

Video

Hard to say whether the brightness of -8.4 is accurate, though.





NIL DIFFICILE VOLENTI


Edited by midtskogen - Wednesday, 13.08.2014, 18:16
 
WatsisnameDate: Wednesday, 13.08.2014, 23:45 | Message # 2520
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The flare magnitude calculation itself is fairly straightforward, as it's just the distance, geometry, and orientation of the satellite and its panels relative to the observer and light source. However, it is also very sensitive. A few tenths of a degree difference in angle can cause a full magnitude difference in brightness.

Sources of error will be therefore be
(i) Observer location uncertainty (very small, since you're using GPS coordinates).
(ii) Satellite location uncertainty (depends on how old the TLE is).
(iii) Satellite orientation uncertainty (haven't a clue).

I've checked flare intensity against other sites and software and they don't always give the exact same answer, but it's usually within a magnitude, or perhaps two mags at worst. If heavens-above told you -8.4 I'd say give or (more likely take) 1 or 2 mags. Calsky gave you a -7.4 for the same flare, with an angle offset of 0.02 degrees and 0.3km centerline distance. Also, it helpfully warns

"This is a spare satellite or its status is unknown. Brightness estimate may be unreliable and flare time accurate to a few seconds."





 
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