ISS solar transit – April 25, 2018

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And yet another solar transit by the ISS. This time I was not sure that I could get to the location predicted via CalSky, so I did not have great expectations…

But, luckily, after going a bit over the speed limit ;), I found myself in a nice field of…green stuff. Nevertheless, this type of astrophotography is never easy, so a few clouds had to cover the Sun just 5 minutes before the event…

Again, luckily, the clouds dispersed 1 minute (!!) before the transit, so that I could focus and wait for the black silhouette of the ISS to pass. Seeing was terrible, but the pass was favorable with many details of the ISS structure well resolved.

I might have been speeding on the roads, but it is nothing compared to the speed of the ISS in orbit…the transit lasted about 0.5 seconds…

The setup: homemade 150mm F/5 refractor (iStar lens), Herschel wedge, 2.7x APM coma correcting barlow, Baader green filter, ASI 174MM.


The cloud that formed 5 minutes before the event:


A short animation (resized) showing the event at a very low frame rate:

ISS APRIL 25.gif

A single frame (the best out of about 36), showing the ISS near sunspot 2706:


And the sequence:

ISStransit April 25a.jpg



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