The Hurtling Moons of Barsoom – Imaging Phobos and Demios

Nope, not even close. The bottom left is 98 Psc mag 4.8, 49′ from mars, the top right is 95 Psc mag 7.5, 17′ from mars. Demios is mag 12, 1’13” from the center of mars. Phobos is mag 10.6, 23″ from Mars. Mars itself is about 21″ across which would be 5 pixels at the scale of this image – the blown out central body above is 60 px, about 4′, totally obliterating the moons. The image is 30 sec ISO 800 through the Takumar 200mm lens wide open at f/4.

I went out on a different last night to try a bunch of exposures. As it happens, the shortest I tried was 1/1000 of a second at ISO 800 through the 200mm Takumar at f/4. At that exposure the body of mars is visibly round at about 6 pixels but it would be hopeless to think about seeing the mag 11 and 12 moons. Nevertheless there is a faint smudge in the correct spot of one of them to be the inner moon. I give you FauxBos… This is a 4X blowup.

Mars with FauxBos

Back in reality-land I measured the size of overexposed Mars in a bunch of exposures at ISO 800. It scales fairly smoothly . At 1/500 sec Mars is 15PX, at 1/60 sec it’s 30PX. Phobos was about 30″ or 7px from the center of mars, deimos about 1’17” or 16px. So somewhere below 1/60 sec Deimos would not be swallowed but would probably too dim to see.

I may try this again when I have my new telescope although the fundamental problem remains. This article is not as discouraging as some i’ve seen. This cloudy nights post actually has amateur photographs of the moons although done with much better equipment than i am using.


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