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Mars - 10 Feb


brianb
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A beautiful evening yesterday - clear, transparent, calm, seeing good (by local standards), very little dew - the temperature got well below freezing but it was really comfortable. Started imaging fairly early whilst there was still some interference from local heat plumes, using a 2x Powermate with my CPC1100 to get a focal length of 5.6 metres (f/20). Here's the result of this early session:

Mars-100210-2152-composite.jpg

2010 Feb 10, 2152 UT. CPC1100, 2x Powermate, Astronomik type 2c colour seperation & Planet Pro 742 filters, DMK21. Transparency excellent, seeing fairly good with almost constant but small amplitude boiling motions (about 6/10). Temp -4C, wind calm.

Top row: RGB composite; LRGB composite using red channel as luminance; LRGB composite using IR channel as luminance; simulation (Starry Night Pro).

Bottom row: IR, red, green & blue channel images. Best 500 from 3000 frame AVI stacked for each channel. All channels upscaled 56%.

I was intending to make more series at higher magnification later in the night, but unfortunately a light breeze set in, and as this was from the sea, the temperature variations were large and the seeing became impossibly wobbly. :bawling: Still my best Mars this opposition, though.

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Thanks peeps!

I thought the SNP simulation was just a further process of the third one...

My bad, I suppose I should label it more clearly. I just thought it would be interesting to show the simulation since the SNP Mars surface detail is compiled from probes but obviously only shows an "average" (e.g. the polar cap is wrong for the season) but does show the right features, correctly tilted etc. Makes it easy to see which features are different from usual.

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the IR shows better contrast than red it seems, I found the opposite true as IR was noisy

It depends on which filter you're using. I found the Planet Pro 805 let through insufficient "light" for my camera, the exposures were long & the seeing was having an effect. The PP 742 works much better. Even so the required exposure is about 2x as much as the red colour seperation filter requires.

I avoid turning up the gain to max so as to help keep the noise under control. But the real secret is to shoot load & loads of frames so you can reject most of them for being too "wobbly" & still have lots left to stack. This particular IR AVI was shot with exposure 1/45 sec, gain 850, 3000 frames of which only 500 were stacked.

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