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Wednesday, July 20, 2011


The Shuttle Shoots Stars Tonight (Wednesday July 20)

UPDATE: Got it! Despite the cloud. Pictures later on, dinner first. Now it's later, the pictures are up.

The International Space Station passes by the bright red star Antares at 18:02:10 ACST as seen from Adelaide on Wednesday July 20, 2 minutes after the space shuttle Atlantis has skimmed the same star (click to embiggen). The ISS will look like a dot, not like the icon in the image. Antares is above the eastern horizon.

While the last time to see the shuttle and the ISS together was last night (with most people clouded out, sigh - still, you can see some images here), you can see the shuttle one last time tonight.

In Adelaide and Perth the Shuttle/ ISS pass is quite dramatic.

In Adelaide, the shuttle is approximately magnitude -1.1 (as bright as Sirius) and passes just 25', less than a quarter of a finger-width from magnitude 0.9 Antares at 18:00:10 ACST. Two minutes later the ISS skims past Antares a bit further away.

Note the time is given in seconds, the shuttle and ISS move relatively fast, and although they are above the horizon for 6 minutes, there is only about two minutes when they are really bright and passing interesting things.

The bad news is that the pass is only 6 minutes after the end of civil twilight, so the sky will be only moderately dark (although the Shuttle, ISS and Antares will be readily seen, the other stars may be harder to see). Antares is about 50 degrees (around 8 hand-spans) above the eastern horizon, and the Shuttle and ISS pass from north-west to south-east.

The path of the STS-135, the space shuttle Atlantis, across the Adelaide sky from 17:57 to 18:02 ACST (click to embiggen). Maximum brightness and closeness to Antares is 18:00:10 ACST.

In Perth the Shuttle and ISS pass close to bright Alpha Centauri, with the Shuttle passing at 18:01:45 and the ISS skimming half a finger-width away at 18:03:55. However, the passes are right on the end of civil twilight, so the sky will be fairy bright (but you should still see the shuttle and ISS reasonably well)

The East coast has the pair skimming low over the southern horizon (and not as bright as Adelaide or Perth), and Darwin and Alice Springs miss out all together.

As always, location, brightness and timing are very location dependent, so you will need to check CalSky and Heavens Above for predictions for your location.

Tomorrow night there is a slight chance we could see the shuttle just after the de-orbit burn.

Cloud cover predictions can be found at SkippySky.

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Atlantis & the ISS have just passed directly overhead here in Bendigo, central Victoria at approx 6:30 pm local time, about 1 to 2 minutes apart. They both reached a similar maximum brightness. They were just far enough apart to make it difficult to see them both at once. Very spectacular to watch the pair go overhead.

Chris Wyatt.
Cool! Although it was difficult to see both, the ISS was clearly rising as the shuttle was setting, so I could rapidly switch between both.
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