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Mercury IR on 3rd June 2017


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About this observation
Chris Hooker
Time of observation
03/06/2017 - 09:30
Observing location
Didcot, Oxfordshire
25 cm Newtonian & 3x Barlow
Imaging Source DMK21AU04.AS camera
Baader IR-pass filter
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Mercury is currently well-placed in the morning sky, reaching a decent altitude before the Sun heats the ground and spoils the seeing. This observation was made in daytime: the dark background comes from the use of an IR filter and histogram adjustment. The verification images are independent stacks of the best frames from two groups of videos, and are reasonably similar, indicating that the markings seen are genuine surface features on Mercury. From a total capture of 13 AVIs, each around 4000 frames, the final image is a stack of only 412 of the best frames selected from all the AVIs, with wavelet sharpening and histogram adjustment in Registax.

A reference image from Messenger data is shown in normal and blurred form for comparison. Thanks to Steve Knight for generating this for me in Sky Safari. The responsibility for degrading it to match the quality of my image lies entirely with me.


Fossil Light's picture

Great work on a very difficult object Chris. I wondered what the altitude of Mercury was when you imaged it?  Can you confirm the time was 9.30BST. I also wondered how you managed to find the planet?



Chris Hooker's picture

Thanks for your comment, Martin. My imaging session on Saturday lasted about an hour between 10 and 11 am BST, so I put the time as 0930 (UT). According to Stellarium Mercury was at an altitude of 50 to 54 degrees.

Finding it is fairly straightforward with a polar-aligned mount. Mine is an HEQ-5 Pro, which also gives a coordinate read-out on the handset. I start from the Sun (with a sub-aperture solar filter), then make offsets in RA & Dec calculated from the coordinates read from Stellarium. A key point is to focus on the Sun, so I know that when I remove the solar filter and start looking for Mercury it will also be in focus. I use a crosswire eyepiece so the focus of my eye doesn't wander while looking for a pale white speck in an expanse of blue sky. Good transparency is important: any slight haze or cirrus can make spotting the planet much harder.

Fossil Light's picture

Hi Chris,

Thanks for the reply that is very interesting. Lots of top tips to help in finding the planet in the daytime.

I could use a similar method but using alt and azimuth on my Dobsonian calculated from Sky Safari. Always wanted to image surface  detail on Mercury but never wanted to risk scanning around too much close to the sun.

Thanks again


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