On the morning of the 12th May, I had some very good seeing – the best I’ve had all year, and I was able to record some images of Jupiter and Ganymede in very good conditions, allowing surface details (albedo features) to be seen on Ganymede – one of the Galilean Moons of Jupiter, 750 million kilometres away!
I’ve created an animation of the best frames from the morning session – click the image below to view the animated gif. Keep reading on to see the best individual images and more technical details.
The animation spans almost 1.5 hours, starting with the last of Ganymede’s shadow as it finished transiting the disc of Jupiter, and ends with Ganymede about 20 minutes away from starting its transit.
Continue reading for more information and to see the best individual frames from the morning session.
It was a very cold morning, getting down to 4°C (cold for my area) but luckily my peltier cooling on the primary mirror (which I had set to turn on for 75 minutes before I started imaging) brought the mirror down to ambient temperature and it stayed within 0.5° (the magic number) during the whole session.
I used my normal Planetary Imaging Equipment to capture these images, recording at 30fps (1/30s exposure) for 43 seconds in each channel. Max gain and 100 gamma was used in each channel, except for Green channel where gain was slightly less.
Approx 600-700 frames were stacked in each channel using Registax.
The seeing improved as the session went along, and may have continued to improve but I packed up at 5:30am and headed back inside to get ready for work and get to the train station for the 6am train!
Something in my imaging train was fogging up as the scope was pointed almost straight up (it was a very dewey morning) and I was losing incoming light.
Hopefully I get a few more mornings like this in the next month – processing this data was a pleasure compared to what I’ve had to do lately.
Thanks for looking.