According to CalSky.com there are several solar transits this week, creating some last-chance imaging opportunities. Ideally I wanted to try and image Atlantis as a separate object to the ISS, as it's tricky to reliably identify once it's docked. So, all that was needed was a transit to occur either just before or just after docking, some clear skies for the critical second, and knowing where to set-up my camera gear.
By good fortune, CalSky.com was predicting a pre-docking transit with the centreline crossing England just north of Corby for early afternoon on Sunday. So, armed with camera's, scopes, laptops and a sat-nav, my mate Dave and I headed off in good time to set-up. Using Google maps, we'd identified a convenient entry into a field just north of the village of King's Cliffe, so off we went.
Cloud cover was a major worry and initially hampered Dave's attempts to find best focus through his scope, but as transit time approached the clouds began to clear and the adrenaline started pumping. For those who haven't tried transit imaging, the emotions are hard to describe. The transit was predicted at lasting only 0.56 seconds, so everything had to come together exactly at the right time. No second chance. Camera alignment, focus settings, self-timer settings, exposure settings being changed down to the last second to compensate for varying cloud cover, clock-watching to get the start of automatic exposures timed just right. And of course - would the clouds be clear of the sun for the critical second. Excitement, anticipation, panic, nerves, apprehension.... they're all there.
I'm pleased to say it all came together - here's the results.
Details -
Size of ISS = 60.1".
Distance from camera to ISS = 460km.
Transit duration = 0.59s
Images taken 2h 27m before docking.
Nikon D300 + 420mm telephoto + Baader solar filter.
Continuous exposure settings set to take 5 fps for 20 seconds at 1/1600s and f8. ISO 200, starting at 13.39 and 44 seconds BST.
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| A field somewhere near King's Cliffe |
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| Worry - will the cloud spoil the day? |
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| ISS at 13.39.56 seconds (2 image composite) |
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| Close-up, passing across a field of sunspots |
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| Atlantis - spot it if you can! |
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| Atlantis 13.39.58 seconds (2 seconds behind and in hot pursuit of ISS) |
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| Close-up! Passing between sunspots AR1249 and 1245 |
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| Path of ISS and Atlantis. |
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