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Venus nightside at 1000nm 25th April 2020


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About this observation
Martin Lewis
Time of observation
25/04/2020 - 19:52
Observing location
StAlbans, UK
444mm Dobsonian
Edmunds 1000nm filter 25nm bandwidth
22mins accumulated exposure time
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One composite image from several gathered over the last few days attempting to capture surface details on the night-side of Venus using a 1000nm filter with 25nm bandwidth. This particularly photogenic image is 21.6mins of accumulated exposure using an ASI174MM camera at prime focus on my 444mm f4.4mm Newtonian. Imaging has used the ASI camera but also a Chameleon3 camera with the same IMX265 chip as used previously by Anthony Wesley and Phil Miles and reported in the BAA Journal in Oct 2017.

Camera and filter kindly paid for by a Ridley grant from the BAA and without which this would not have been possible.

More hopefully as we near inferior conjunction if the weather cooperates.

Invaluable help in this challenge from Anthony Wesley and Phil Miles in Australia, David Arditti closer to home, and Paul Abel whose suggestion got the ball rolling.


Chris Hooker's picture

That's a remarkable image, Martin. It looks as if there are a couple of slightly darker patches at lower right around the 4 o'clock position? If they are real they could be surface features: do they appear on any of your other images, or are they just artefacts?

I look forward to seeing more results like this. Well done!


Fossil Light's picture

Thanks Chris.

The larger, elongated, slightly darker region area near the limb at 4 o'clock that is on this image is also at the same position and with a similar shape on a second independent Winjupos combination based on 7x3min videos taken with a different camera in the same session- the Chameleon3 camera I mentioned above. Like with your independent stacks with your Mercury images it gives some assurance that this is a more than likely real feature. I have data from the following night and we'll see if it shows at a similar location on there too.

The Venus bright crescent is not a mask placed onto the image to define the shape- it comes out like that in the processing BTW


Jeremy's picture

This is an amazing image, Martin!

Fossil Light's picture

Thanks Jeremy,

This is work in progress and I have more results to post but thought that was an aesthetically pleasing one to start with. Hope to gather more data as the crescent narrows but opportunities depend very much on the weather and time is running out with Venus rapidly approaching inferior conjunction.


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