ISS - extremely good lunar transit

Posted by: Szabolcs Nagy Comments:0

Lunar transit is something I’ve been craving for a long time now. I had some experience in this from the past, but it never turned out to be as good as I expected. But let’s be honest, it is not an easy task. Not only commitment required, but also circumstances must be perfect – Moon high in the sky, appropriate ISS pass, good light conditions, good weather conditions, etc.
I check Calsky every now and then just to know if something is happening. This prediction came up. Then double checked in Heavens Above.

Detailed forecast for the lunar transit – Calsky

Centreline from Calsky – the website has some ongoing issues with Google Maps, but it does not affect forecasts

Star chart for the pass, but Sun was still up so it was more relevant to me for the timeline

I was not really sure what kind of composition should I go (if clouds clear). With illuminated lunar transits there are a few things one should pay attention. First of all if ISS passing in front of Moon, the station will blend into the background (lunar surface). Also the panels are rarely facing toward us (it always does toward Sun), mostly we see them from the side. Keeping these in mind I was planning to have ISS a little bit in front of Moon and off the lunar surface too. It seemed like a good combination, a bit of this and a bit of that… But the app I am also using (ISS Detector) is not always accurate though. If it had been a planetary transit, I would have been more worried, but with Moon a tiny error does not make any difference…
Life is the best director – I could not have found any better place for imaging, it all happened according to my expectations.

Because this transit happened during daytime, I assumed Moon and ISS will be much more pale. But after setting up the scope it was clear to me that the light conditions were just perfect. Moon was really contrasty on my laptop screen which gave me hope for something really good to come.
Below on the equipment photos you can see my dobsonian telescope on an eq platform. It usually tracks the sky well, but lately not that well, presumably gears are wearing off (need to be fixed). But I realised if I apply some pressure on the platform, it tracks very accurately. I placed my accessory box (a wine box basically) and the car jack as extra weight onto the dobson base – couldn’t find large enough rock in the carpark. (laptop is on a plastic sheet, not on the wet ground 🙂 )

..but the horizon was nicely clearing up.

I’ve tried to add all the frames with ISS on them and blend into on single photo. I did it but the final result is not something I really like to be honest. Daytime passes are trouble from this point of view, plus the seeing was not great- Whatever I did the lunar surface remained blurry. I’ll share the composite photo anyway…

First attempt to combine frames with the lunar background – ISS frames look awesome, but the lunar surface is very blurry

After hours of layering this composite photo seems to be my best attempt – ISS frames are fairly contrasty and detailed, also the Moon surface shows somewhat more details too.

Eventually a video I have made from the footages. Most importantly you will see the raw unprocessed footage of the transit at real time speed (double click on video for full screen).