by Fil » Sat Feb 27, 2010 11:52 am
Really nice picture! Great framing with the bridges!
Does anyone know which direction they were going? Hmm, dumb question, I will check... Judging from
http://www.calsky.com, and it seems they both were going from roughly North to roughly SouthEast, so one the image it would mean down from top to bottom.
Also a curious thing, is it looks as if someone passed in front of the camera at least 3 times (if it was a single exposure and not around 4), because there are 3 tiny interruptions in the trails... Also interesting to note is that these interruptions (if happening at the same instant in time) show that one of either ISS or STS-130 was in front of the other one, and not both following a side-by-side route as one could imagine at first glance
In fact, calsky tells me the ISS was 2 minutes "behind" the Shuttle. So The shuttle is the trail on the left, and the ISS is the trail on the right!
(because it ends "sooner", it seems)
So we can observe the ISS is brighter most of the time, and the Shuttle is actually darker, but still peaks in brightness nicely
..
Well, being late through night, and with the info from calsky about the time of the ISS pass, I figured I'd try finding known constellations in the sky!.. And indeed I spotted Lyra to the left the the ISS trail, slightly higher in the picture than the flare from the ISS (right trail). With Lyra found, finding Hercules suddenly became a lot easier. (M13 seems to be visible in a thick faint train!) Next, Corona Borealis pops-up really nicely, but Boots is not easy to spot because Arcturus is out of the picture.
Anyway, I wanted to find a star near the celestial equator (as these leave the longest trails in the least amount of time), and I picked up Antares, the brightest star at the bottom left of the picture, at the heart of Scorpio, at Declination -4º.
The trail left by Antares has a length of 56 pixels. The angular distance between Antares and Alniyat (sigma Sco) is just over 2 degrees, and measures 81 pixels in the picture. This tells me that the resolution there is about 1.49 arc-minutes per pixel, in the vicinity of Antares, leading to Antares having a trail of 83.6 arc-minutes. Given the sky turns about 15 arc-minutes per minute, that means the total exposure took roughly 5.6 minutes (having the -4º declination into account) or just over 5 minutes and a half. Perhaps it would have been 4 exposures of 90 seconds. It is very rare to do 5-minute exposures in city skies. You would have to stop-down the aperture somewhat, and you would not be able to spot the trail left by of M13!..
Really nice picture! Great framing with the bridges!
Does anyone know which direction they were going? Hmm, dumb question, I will check... Judging from [url]http://www.calsky.com[/url], and it seems they both were going from roughly North to roughly SouthEast, so one the image it would mean down from top to bottom.
Also a curious thing, is it looks as if someone passed in front of the camera at least 3 times (if it was a single exposure and not around 4), because there are 3 tiny interruptions in the trails... Also interesting to note is that these interruptions (if happening at the same instant in time) show that one of either ISS or STS-130 was in front of the other one, and not both following a side-by-side route as one could imagine at first glance :)
In fact, calsky tells me the ISS was 2 minutes "behind" the Shuttle. So The shuttle is the trail on the left, and the ISS is the trail on the right! :) (because it ends "sooner", it seems)
So we can observe the ISS is brighter most of the time, and the Shuttle is actually darker, but still peaks in brightness nicely :)..
Well, being late through night, and with the info from calsky about the time of the ISS pass, I figured I'd try finding known constellations in the sky!.. And indeed I spotted Lyra to the left the the ISS trail, slightly higher in the picture than the flare from the ISS (right trail). With Lyra found, finding Hercules suddenly became a lot easier. (M13 seems to be visible in a thick faint train!) Next, Corona Borealis pops-up really nicely, but Boots is not easy to spot because Arcturus is out of the picture.
Anyway, I wanted to find a star near the celestial equator (as these leave the longest trails in the least amount of time), and I picked up Antares, the brightest star at the bottom left of the picture, at the heart of Scorpio, at Declination -4º.
The trail left by Antares has a length of 56 pixels. The angular distance between Antares and Alniyat (sigma Sco) is just over 2 degrees, and measures 81 pixels in the picture. This tells me that the resolution there is about 1.49 arc-minutes per pixel, in the vicinity of Antares, leading to Antares having a trail of 83.6 arc-minutes. Given the sky turns about 15 arc-minutes per minute, that means the total exposure took roughly 5.6 minutes (having the -4º declination into account) or just over 5 minutes and a half. Perhaps it would have been 4 exposures of 90 seconds. It is very rare to do 5-minute exposures in city skies. You would have to stop-down the aperture somewhat, and you would not be able to spot the trail left by of M13!..