In the From the Vault series, I feature an older image which hasn’t been seen here before and I talk about the capture and processing and hopefully highlight why this image is special to me.
The feature image in From the Vault this week is a high-resolution mosaic image of the Clavius crater on the Moon, as well as some other craters captured on the same night. It was the day before New Years Eve in 2007, the weather was hot and the seeing was variable. Fortunately it steadied for a period of about 5 minutes, long enough for me to capture enough data to compile this 4-frame mosaic of Clavius.
It’s my highest-resolution and best image of Clavius, or any crater i’ve imaged so far. The lighting was perfect, giving just enough contrast to help the small craterlets and rilles stand out while still fully illuminating all the features. The resolution is about 200 metres per pixel at the focal length I was working at (approx 10.5 metres).
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Continue reading to learn more about the capture and processing of this image, as well as to see some other crater images captured on the same night.
I used my standard Planetary Imaging Equipment to capture the data – the 12″ Newt on an EQ6 with the DMK21AU04, 5x powermate and Astronomik Red filter. Using the Red filter on its own allows a more narrow bandwidth of light through and helps the sharpness of the image in less than ideal conditions.
At the focal length provided by the 5x powermate with the extension of the filterwheel (approximately 10.5 metres), the whole of Clavius could not fit in the field of view of the 640×480 pixel resolution DMK21AU04. For this reason, a 4-panel mosaic was needed to capture the whole of the crater (2 across, 2 down).
With the moon being so bright, exposure wasn’t an issue and I could use the full 60 frames per second limit of the DMK21AU04, which helped freeze the seeing and provide some good quality frames. I recorded each panel for 40 seconds, giving 2400 frames each. The average seeing meant I could only stack 200 frames from each panel, but it was enough to give a sharp, noise free image. Registax 4 was used for multi-point alignment and stacking of each panel, and the mosaic was assembled in photoshop and then the whole image was taken into Astra Image for LR deconvolution, before being opened again in Photoshop for final touches.
The image received some great feedback initially, and was more formally recognised when it won 1st place in the Solar System category of the 2008 South Pacific Star Party astrophotography competition.
Some other lunar crater images taken that same night are presented below. They’re not at sharp and smooth as the Clavius image, which shows how variable the seeing was and how lucky I was to get a steady stream for the Clavius mosaic.
The Clavius mosaic is available to purchase as a greeting card, matted, canvas or framed print at RedBubble.
Thanks for reading and thanks for allowing me to share with you.