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Phobos and Deimos


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About this observation
Nick James
Time of observation
13/09/2020 - 01:54
Observing location
Chelmsford, UK
Celestron HD11 + FLI6303

It is a bit of a cheat since this is an image, not a visual observation, but here is a response to Richard McKim's observers' challenge. This camera is not ideal for the challenge since it is intended for deep-sky images. It has a mechanical shutter and no anti-blooming so there is a strong overflow for bright objects down a column. The pixel size is also relatively large (0".64/pix). This is the result of a stack of 10x1s images (about my shortest possible exposure) processed with a radius 6 median background subtract. Deimos is easy, Phobos more difficult since it is closer to the planet but the astrometry of both is within 0".2 of the ephemeris positions. The circle in the inset shows the current diameter of Mars at this scale (20".7 arcsec).

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