julian weßel - astrophotography

ISS transit in front of Jupiter 


On 9th June, 2015 something very rare happened: an ISS pass in front of the disc of Jupiter took place just 30km away from my home. At first I was uncertain if this event could be captured on camera but I decided to give it a try.

So I calculated the nearest possible location where the transit could be seen, the small village Kirchellen, Germany. But there were two things that I had to keep in mind while I chose the location. The first was to have a good horizontal view to the west because Jupiter would be only 13 degrees up the horizon at the moment of the transit and the second one to have a safe place to set up my scope without disturbing anyone.

After a few drives to the village I decided that a near field would be the best option. The transit line of this ISS pass was only 50m wide so I had to be very precise.



At about 8 o'clock I arrived at the location and started to set up my 10" Skywatcher Newton on a NEQ6 and connected the laptop to the camera. I had a great view to the west and I was happy the weather was on my side. Not a single cloud appeared in the sky.


After the set up was done I checked my camera to avoid any interference. The camera I used for the transit is an Alccd5L-llc planetary cam. You can use it as an autoguider too, which makes it a great tool with a cheap price. I've made a test video with it you can check it out here.

But there is a disadvantage with the software the camera uses. On old laptops EZPlanetary doesn't run stable and because of this I was very nervous if I could capture the transit in a good way.

The settings of the camera had to be optimized to a really fast shutter speed because the transit would only last about 0,09s.


Just a few minutes to go and I started getting nervous. I hoped, that everything works out now.

The ISS transit in live comment:

11:26:10pm : Something bright is ascending the horizon! This must be the ISS! My heart is         pounding at this moment. I start recording Jupiter with EZ Planetary and hope it doesn't freeze.

11:26:30 The ISS is aiming for Jupiter. This looks good!

11:26:56 I can't belive this is happening so perfect. The ISS with 17.000mph and 4 humans in it is crossing the small disc of Jupiter in this huge sky. I'm overwhelmed.

11:27:05 I'm checking the video I made with my camera and i see that it goes right through the middle perfect job! I'm still shaking.


This is the result I was hoping for:



I really enjoyed that event this evening and I was happy to capture an ISS transit in front of Jupiter. To see two objects seperated by 750.000.000km aligning perfectly is an unforgettable experience.