image by Bob Pilz
The attached image (2x enlargement) is of an area extending east from Posidonius to the northern head of Rima G. Bond - both a normal and negative (and highly contrast enhanced) version are shown. When examining the normal image I saw what appeared to be a rille east of Posidonius about 1/3 of the way to the head of Rima G. Bond which isn’t indicated in Rukl and which wasn’t apparent on Lunar Orbiter images either. Incidentally, in the LPOD Photo Gallery there is a Posidonius image by George Tarsoudis that faintly shows this rille. The recent LPOD showing a negative image of the moon and David Dench’s follow-on image on the Lunar Observers forum incented me to try that technique on other lunar images to see how useful it might be not just for ray analysis but in general. Here the negative image makes the rille much more apparent and appears to show a series of craters or perhaps collapse pits along its course that are almost completely invisible in the original image. I can’t be certain this is really a shallow rille or maybe just a crater chain, but creating a negative image and enhancing its contrast really helped make everything that was in the image much more visible.
Bob Pilz
Technical Details:
10 Oct, 2006, ~09:25 UT. 200mm f/6 Newtonian reflector, Televue 3x Barlow , DMK 21BF04 B/W camera, ‘Blue’ IR-block filter, .20 arcsec/pixel; 30 fps, 1/60 sec, 600/6000 frames stacked. Processed in Registax, ImagesPlus, PS CS. A white line is drawn parallel to the rille in the right image.
Related Links:
Rükl chart 15
Bob’s website
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