August 5, 2022

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Seeing in the Dark

Originally published September 13, 2012 LPOD-Sep13-12.jpg
image by Rik ter Horst

About a year ago I observed Tycho under good conditions with my 40 cm telescope. At that time Tycho was located near the border of day and night so the central mountain was entirely hidden in the shadow. At high power I suddenly was triggered by a very diffuse dot in the middle of the dark floor of Tycho and first I thought I was dealing with some reflections between my eye and the eyepiece, but the dot stayed fixed with respect to the crater so I suspected this speck to be the central mountain indirectly lit by the sunny crater rim. I even could see it being lit from that direction, and this observation made me decide to capture it with a camera one day….

That day was last Sunday morning, when my friend Emil Kraaikamp and I decided to do some imaging. We were lucky to have the right phase to make some images of Tycho as well. So here are two images, the left showing Tycho as we know it, the right showing detail within the dark crater floor, including the central mountain which is lit by the crater rim on the right! Actually, the second image is just a processed version of the first image, made with the 40 cm telescope and a Basler Ace camera. I was happily surprised to see an exact copy of my visual observation from one year earlier. Processing is done by Emil.

Rik ter Horst

Technical Details
2012/09/09 03h10m UT. 40cm F/5 Dobson on Equatorial Platform + barlow lens. Camera: Basler Ace acA640-100gm. Software: Autostakkert!2, Photoshop.

Related Links
Rükl plate 64

Yesterday's LPOD: Lost in Space

Tomorrow's LPOD: What is the Best Lunar Telescope?


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