Overhead ISS Transit

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On September 24th, 2015, it was a crystal clear night over Northern Italy. The day before I had come across the news (wonders of Facebook :mrgreen: ) that a transit of the International Space Station (ISS) would take place almost overhead during the morning twilight. The ISS was expected to cut straight across the entire sky dome, passing very close to the local zenith, for a total transit duration of about six minutes (from 6:23 to 6:29 CEST).

Had I known about it beforehand, it would have been a terrific opportunity for some hires space station imaging. Unfortunately it was too short of a notice, because the weather had not been favorable on the previous day(s) and my mount’s pointing model was too old (i.e. not accurate enough) and therefore had to be rebuilt from scratch.

So, I had to make do with wide-field imaging. To this end, I got up around 6:00am and set up my camera on a fixed tripod in my backyard. I used my 8-mm Samyang fisheye lens for the widest possible field of view (almost 180°).

Needless to say, the transit started perfectly on time. The ISS popped up from the NW, zipped across the autumn and winter sky: Andromeda, Perseus, Auriga, Gemini, Canis Minor, and then headed SE, quickly plunging into the morning twilight. Judging from the trail, the ISS reached a maximum altitude of about 78°.

Here’s a photo showing the whole transit, which is actually a composite of 22 x 15 s exposures taken with my Canon 500D DSLR at 400 ISO and the fisheye lens stopped down to f/5.6. Also available is an annotated version of the photo. Click both images for a larger version with all the relevant technical details.

Enjoy!

ISS Transit of September 24, 2015 over Northwestern Italy

ISS Transit of September 24, 2015 over Northwestern Italy

ISS Transit of September 24, 2015 over Northwestern Italy

ISS Transit of September 24, 2015 over Northwestern Italy (annotated version)

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