Following up from yesterdays Venus imaging of the planets night side (thermal emission from the surface at 1um), I had another go tonight and the seeing was somewhat more forgiving allowing me to try a longer exposure. The night side limb seen this 1-micron image shows up far better than yesterdays effort and there is a very obvious dark patch at lower right. I have not processed or subtracted light and dark frames as yet to clean up the image but the result looks promising. 500 stacked images here.
What brand filter are you using? Is it a normal 1.25" thread? I see Astronomik are now selling 742nm and 802nm IR filters, I've thought about getting one to fill one of the empty holes in my filter wheel.
Bird, the filter was given to me in its raw form as a piece of excess. I then had a 1.25-inch threaded holder made up. I believe there is a commercially available filter (Schott RG100 ) but not sure where you can get them from.
Regarding the other IR filters to fill the filter wheel holes, they'd make a great addition to your planetary imaging arsenal especially if you want to get in to imaging Mercury. And, depending on type of seeing conditions, can greatly improve the visible distorting effects of the atmosphere when imaging surface features of Mars in monochrome.
Regarding your question Robert, I take the dark frames simply to remove the half dozen or so hot pixels that appear when using the cameras integration mode. The flat fields are a precautionary measure, even though the stacking process essentially averages out any possible dust specs that may introduce artefacts in the image.
Starkler..lol - Yeah..I've had one or two comments that it was an unusual photo of the Moon! I think they were trying to be nice.
