October 16, 2012

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Two Views of Ancient Heros

2012 (left) and 2005 (right) sketches by Erika Rix, Texas

It’s really fun to race against time while sketching along the terminator during the waning gibbous phase. I sound like a broken record stating that it’s much easier when sketching in the highlights on black paper instead of the shadows on white while working along the terminator, especially when the feature can be swallowed up by shadow. My first sketch of this pair of craters was in 2005. Working out the eyepiece combo with the magnification, the 2005 sketch was with my 70mm refractor. The two observations are nearly the same with regards to lunation and time of night plus altitude and azimuth figures. The big exception is in libration:

2012 10 04: Lib. Lat: +00:26, Lib. Long: +00.35; 2005 02 27: Lib. Lat: -00:50, Lib. Long: -05.04

This is a very good example how libration affects the view we see on the Moon. As a side note to help put things into perspective of what you can expect to see through a telescope at 171x magnification, crater Hercules H is 7km wide.

Erika Rix

Technical Details
2012 10 04, 0500 UT - 0636 UT. 6" RC on a GEM with an 8-24mm zoom eyepiece, 171x magnification, no filter. 69F, 70% H, light breeze, lightly scattered, Antoniadi III, T 4/6. Phase: 314.8 degrees, Lunation: 18.12 d, Illumination: 85.2%. Eyepiece sketch on black Strathmore Artagain paper, white Conte’ crayon and pencil, black oil pencil.

Related Links
Rükl plate 15
Erika's website

Yesterday's LPOD: Parallel And Perpendicular Lighting

Tomorrow's LPOD: Thumbnailed Moon


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