Jupiter with Io Shadow Transit, 29th March 2009

On Sunday morning, we had beautiful clear skies and I was able to capture an image of Jupiter with Io’s shadow in transit, followed by Io itself shortly after.

Unfortunately the conditions weren’t great and the image is really affected by the poor seeing, even though Jupiter is now climbing to a respectable 40-45° in altitude before dawn.

I captured 9 RGB runs but chose the two sharpest images for display here. They were taken approximately 30 minutes apart. Io can be seen just inside the limb in the second image.



If you’re interested in the more technical details of capture and processing, please read on.

The data was captured with my usual Planetary Imaging Equipment. I still haven’t cleaned the dust off the CCD of my DMK21AU04, and combined with not being polar aligned, I was constantly battling Jupiter drifting through the field of view and me using the hand paddle trying to avoid the dust motes!

I recorded at 30 frames per second (fps), with gain at maximum and gamma at 111 in all channels. Because Io moves so fast, I limited the capture time to 30 seconds, giving me 900 frames in each channel.

The poor seeing meant I could only use 200-250 frames in each channel when using Registax 5 to align and stack the frames. AstraImage 2.5Max was used to apply ME deconvolution and recombine the monochrome channels back into an RGB image.

Photoshop CS2 was used to adjust levels and curves and apply final touches for web presentation.

I’m now without my EQ6 mount for the rest of the week, as I’m taking it into Bintel for a tune-up service (lucky for me it’s cloudy this week!). It hasn’t had a service in about 4 years, and after it has driven around a 12″ Newt with 20-25kg of counterweights all that time, I’m certain it’s overdue. I hope not ALL the gears need replacing 🙂

Hopefully when it returns it’ll run smoother, without backlash and hopefully without any high-frequency vibrations that may be introducing smearing into my high-resolution images. 

Thanks for looking.

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