View cloud cover over the UK in the latest satellite image from the Met Office

Paying your dews

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Sometimes astronomy seems like an extremely demanding hobby. You have to give if you want to get.

Take this current Jupiter apparition. Here I sit in the midst of an almost unheard of run of four or five clear nights, yet turning a scope on the planet more often than not reveals a wobbly, mushy mess due to some appalling seeing. And then there’s the dew. Each morning I have to scrape the moisture off my car windows, so you can imagine what it does to my scope sitting outside cooling until the early hours. And there’s another problem right there. If you want to get the best from Jupiter right now you need to be up early… or go to bed late.

All this leads to some frustrating problems for a planetary imager such as myself. Especially if your ultimate goal is to make animations. I love watching my images of Jupiter rotate and to make this happen I need to capture it every two minutes for as long as I can manage. Aching back and freezing joints come with the territory here.

Which made the early hours of 28th September quite a remarkable experience. Deciding to stay up all night, I headed out at 1.30am to start shooting only to find all my kit soaking wet and the planet looking like it was made of jelly. After an hour of capturing awful fuzzy images I gave up, consigning myself to a sleep-deprived night and actually dreading trying to stay up late the following night to get some good shots.

2:14am the shadow transit of Io begins (shadow visible coming in from the left) but the seeing is not so good
 
But at 4am, knowing the Great Red Spot (GRS) was on show I decided to head out for one more go. As anyone else out at that time will attest to, it was a very different sight that greeted us with the atmosphere beautifully calm and tranquil. To add to this we had a shadow transit of the moon Io in progress right across the GRS.
 

Jupiter, Io and Io's shadow taken at the calmest moment of the night, 4:03am. Io is just to the right of the GRS
 

It was the perfect time with the perfect seeing and the perfect planetary activity and the result was also my best shots and my best animation to date.

Of course I could have done without having to blow dry my corrector plate every 10 minutes to clear the moisture off but I guess that’s what they mean by ‘paying your dues’.


The finished animation. 3:55am to 5:22am 28th September 2011