International Space Station with Discovery Docked

On the mornings of Friday 20th and Sunday 22nd March I had a busy couple of mornings, with a bright pass of the International Space Station (ISS) over my location, as well as capturing Jupiter (20th and 22nd) and the Moon. The great thing about the ISS pass was that the Space Shuttle Discovery (STS-119) was docked at the time so I was hoping for good seeing and hoping I’d be able to track it accurately.

I was able to capture reasonably detailed images during both passes, but of course you always want more. For the image on the 20th, my shutter speed was a little too slow so the frames were a bit soft. The lighting and angle meant the backside of the shuttle was facing us and was not illuminated and could not be resolved.

ISS on the 20th March

The image from the 22nd shows a lot of detail and structure in the radiators and also includes the new S6 solar panel that was installed by the STS-119 crew on the 21st March. Space Shuttle Discovery is barely visible – only it’s tail is illuminated and was just about the noise level.

ISS with Discovery Docked on the 22nd March

Please continue reading for more information about the capture and processing and the challenges of recording the ISS!

On Friday morning (the 20th) the ISS went directly overhead, literally. Starting from the NW, heading overhead and setting to the SE, it was probably the worst possible trajectory for me at home. Trees in the backyard mean I couldn’t start imaging it until it was directly overhead so I missed the first half of the pass, and trees in the South Eeast meant that once the ISS reached about 40° altitude I couldn’t image it any more.

So I had a limited window of about 1 minute in which to try and capture as many frames as possible. I use my 12″ Newt on a Dobsonian base to image the ISS, and dob owners will know about the problem of “dobsons hole” – the point where the telescope is pointing straight up and is incredibly difficult to maneuver.

Well unfortunately as the ISS emerged from behind the trees, it was in dobson’s hole and it took me some time to locate the ISS in the finder-scope and to start hand-tracking it. I did manage to get the ISS on about 20 frames but unfortunately my shutter speed was too slow and the frames I captured were soft.

The settings used on the 20th were: 1/1000s shutter speed, 60fps, gamma at 120, gain at maximum. I used my 12″ Newt on the dob base, with the DMK21AU04 through a 2x barlow. I manually tracked the ISS using my 9×50 RA finder, trying in vein to keep it centered on the crosshairs.

On Sunday the 22nd, the pass was even shorter. It was almost the same trajectory but being 30 minutes earlier, only became lit by the Sun once it had passed overhead and was heading towards to the SE. The maximum elevation for the pass was 60° when it first became visible, and headed down from there. I literally had about 15 seconds in which to find the shuttle in the crosshairs and hopefully capture some frames.

Unfortunately, a very thick dew had fogged up my finderscope and my efforts to clean it beforehand were limited. Also, being earlier (and darker), the crosshairs weren’t visible so I was fumbling around trying to get the ISS in the centre but it was over way too quickly. I only managed to capture it on 3 partial frames. I used bits of each frame to construct the image above but there’s still a bit missing.

The faster shutter speed of 1/1250s helped to capture a sharper view and the shuttle tail is just visible. I’m disappointed I wasn’t able to capture more!

Settings for this capture were the same as the last, just with the faster shutter of 1/1250s.

For over a year now I’ve had an old 6×30 finder which I want to convert into a finderscope camera with my old ToUcam to help me track the ISS. I never get around to it but I’m motivated now, I have to do it. It will help a great deal to get a higher hit-rate of frames that have the ISS on it. I also need to fix up the dob base, which is incredible stuff and difficult to turn (I never use it).

With the ISS passing overhead once or twice every two weeks, there’s always more opportunities.. I just seem to be clouded out for 90% of them! To see my other International Space Station images, please check my ISS gallery.

Thanks for reading.