Monday, 25 January 2016

The day ISS transited Saturn

After all the hassle about APOD's fake ISS transit on Saturn, I gave my very best to document the event as real and precise as possible. And will do so in the future....


The exact set up I have used to record the event (photo above was taken in UK)
Skymax 90/1250 MC and 
an ASI120MC cam

Composite photo of six frames of ISS and the stacked Saturn frames (photo of Saturn at bottom of this post)

I booked my holiday a few months ago to Gran Canaria and was planning to take my small travel scope (Skywatcher Skymax 90/1250) with me to do some astronomy there under that wonderful clear night sky.

Before I actually traveled, double checked the app called ISS Transit Prediction just to see what if.. than realized ISS might transit the ringed planet. But I was very sceptical (coming from London lol) as always, you never know the weather and other circumstances that can ruin the careful planning....
But everything went fine, sky was exceptionally clear and everything was ready for a good attempt...
Although I've been in astrophotography for 3 years, I mainly worked with dslr and only recently bought myself an ASI 120 MC planetary camera, I had lots of doubts about my own skills, mainly about camera settings (choosing the right gain and exposure), plus to fine control an eq1 mount with an ASI on it is, well let me say not the easiest.....

This is the original footage, no changes or modifications made to it. I did only debayer it, because I record in FireCapture and it does better job if debayer function disabled during recording.
Exact capture time was 6:51am (25th January 2016)

But here is the final result, a nice video about the best astro-moment of my life. It was uplifting, rewarding and a fantastic feeling to see ISS actually flying through the queen of planets.  By mistake I wrote 2015 instead of 2016 in the title - it happens to me every year after changing the calendar in January :)

Also a time lapse movie (below) from the camera shots. I left my Canon 600D with an 8mm Samyang fisheye lens clicking. It covers partially the setup and the actual event too.


Saturn from that location was at a generous 27° high above horizon at 6:51am UTC. Just for comparison in London it only climbed to 14° only at the exact same time.
Latitude of Gran Canaria, Spain 28°
Latitude of London,UK 51°

Mind that for this photo I was tracking Saturn manually, not motors on eq1 mounts!!!
It is all up to smartly processing the frames.

These are the saved screenshots for me to help finding a proper place near the airport of Gran Canaria, from and from

Centerline for Saturn - large area of the Airport
Centerline for Saturn - close up of a possible suitable area

ISS informations - brightness, elevation and time 

The original Fire Capture log file for the video

Update: for some reason my ASI cam missed one frame after the actual transit, no idea why. I was recording at average of 40fps, normal USB 2 port so might be the data transfer or whatever technical reason...