April 3, 2012

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Latitudinal Band Pan

image by George Tarsoudis

Usually when I observe I sweep up and down, following the terminator. And then I move toward the limb and repeat. George demonstrates how intriguing a sweep perpendicular to the terminator can be. This particular latitude band sweeps past some of the most spectacular lunar sights, starting with Plato nearly at the terminator and moving east to the Alpine Valley. Then there are Aristoteles and Eudoxus followed by the death-crossing fractures near Bürg, and over to the heroes of Atlas and Hercules. Once past the bright but tiny oblique impact pit east of Atlas there is little to catch the eye except the lonely, but hopeful patch of mare called Lacus Spei. When I observe I can see and recognize these scenic giants, but George's image captures many second order gems that I often can't see at the eyepiece. These include the rilles east of Plato and the inner meandering rille of the Alpine Valley. I've seen the dark halo east of Baily but never the volcanic vents that produced it. Again the dark halos within Atlas - at least the southern one - is detectable at the eyepiece, but the concentric and other rilles usually aren't visible for me. In looking back at visual observer reports and drawings from before the 1990s when high quality imaging began to appear it is easy to understand why observers wondered if changes occurred. So many details are at the limit of visual detectability that it was difficult to know which drawings could be trusted. The remarkable thing is how often the classic observers did get details at least approximately right. We are spoiled by today's amateur imaging.
Chuck Wood

Technical Details
Mar 31, 2012. Telescope 10 inch @f/6.3, camera Unibrain fire-i 785, filters Red, barlow 3X.

Related Links
Rükl plates 3 to 16
Full res image
George's website

Yesterday's LPOD: Interrupted Chain

Tomorrow's LPOD: Southwest Corner


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