Big Sunspot; Little Chinese Space Station

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Astrophotographer extraordinaire Thierry Legault has made a name for himself with his images of spacecraft transiting across the face of the Sun. He has done it again by capturing the first-ever image of the Tiangong-1 space station transiting the Sun. The monster sunspot, AR 1476 absolutely dwarfs the Chinese space station (inside the circle), but you can see incredible details of the Tiangong-1 below in a zoomed-in version. Legault had less than a second to capture the event, with the Tiangong traveling at 7.4km/s (26500 km/h or 16500 mph,) the transit duration was only 0.9 seconds! The size of the station is pretty small — as without solar panels the first module of the Tiangong measures just 10.3 x 3.3 meters.

Legault’s equipment was a Takahashi FSQ-106 refractor, a Baader Herschel prism and Canon 5D Mark II camera. Exposure of 1/8000s at 100 ISO.

As Legault told us in an interview earlier this year, in order to capture such images he studies maps, uses CalSky software, and has a radio synchronized watch to know very accurately when the transit event will happen.

“My camera has a continuous shuttering for 4 seconds, so I begin the sequence 2 seconds before the calculated time,” he said. “I don’t look through the camera – I never see the space station when it appears, I am just looking at my watch!”

For a transit event, he gets a total of 16 images – 4 images every second, and only after he enlarges the images will he know if he succeeded or not.

“There is a kind of feeling that is short and intense — an adrenaline rush!” Legault said. “I suppose it is much like participating in a sport, but the feeling is addictive.”

Thanks to Thierry for sharing his latest success, and you can see larger versions of these images, and much more at his website.