Last Voyage of Atlantis

The very final Space Shuttle journey into orbit.

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.



A field somewhere near King's Cliffe




Worry - will the cloud spoil the day?




ISS at 13.39.56 seconds (2 image composite)




Close-up, passing across a field of sunspots




Atlantis - spot it if you can!




Atlantis 13.39.58 seconds (2 seconds behind and in hot pursuit of ISS)




Close-up! Passing between sunspots AR1249 and 1245




Path of ISS and Atlantis.



Shadow Chasing - Endeavour crosses the Sun

After yesterdays disappointment, the weather today was forecast to be worse, but I checked out a favourable spot anyway to try and image the ISS and Endeavour transit, predicted for this morning at 11.43 and 38 seconds. I've only got 3 attempts left to try and image Endeavour before it's pensioned-off, so I had to try and hope for better luck than we had yesterday.

When I arrived at my chosen site near Pulloxhill, Beds, I parked up in a convenient field ......and it started to rain. "What am I doing here?" I asked myself. As the wind was blowing the cloud along at a fair pace I thought I'd stick it out and hope for the best. Fortunately, 10 minutes before the transit started a big patch of blue blew across the sun and everything was looking good.

No other mishaps, and I started my 100 exposure sequence 10 seconds before the predicted start, at a rate of 5 fps, using my laptop on the car seat to get an accurate time fix.

Back home, I was delighted to have captured 3 images which are composited here. The other dot on the sun is the sunspot AR 1216. The enlargements show some detail - one of the sets of solar panels is very clear, though I'm not 100% sure which bit is Endeavour. I suspect it's the dark blob near the centre.

Duration of transit only 0.57 secs. Shadow ground speed 7.5 km/s

Diameter of ISS = approx 65.4 arc seconds

In a field somewhere, with my DSLR and 420mm lens



ISS Transit ID

Following some searching on the web, I've tried to identify the different parts of the ISS that (with a small stretch of the imagination!) can be seen in my image of a few days ago. The solar panels can be rotated to suit the sun's position relative to the station, and are shown at a slightly different angle between the two dates.

As a rough guide to image scale, the area covered by the four sets of solar panels is 361 ft wide x 240 ft long.  The station was imaged at a distance of around 250 miles. As best as I can estimate it, the theoretical resolution on the original image works out at roughly10ft per pixel.

ISS Solar Transit - 13th May 2011

First time I've tried to image the ISS crossing the sun. Seen lots of great images on the web, but naiively thought I'd need more sophisticated gear than I currently have.  Anyway, while browsing the web last night, I happened to check the ISS transit programme on CalSky just for interest. I was surprised to see that the centreline of the next transit was today, a mere 3km from my house. Too good to be true I thought, so I decided to give it a go and hope for the best. The total transit duration was predicted to last only 0.5 secs, so my timing needed to be pretty accurate.
Anyway, here's the result. I have to say I was dead chuffed. The close-up clearly shows the solar panels, with the station modules lying between, at an orientation of what looks like approaching end-on.

Details - 420mm telephoto with Baader solar film. 1/1250s at f8. 100 images taken at 5fps starting 10 seconds before the predicted start of transit.



Composite of 3 images taken 0.2 seconds apart