• Don SpainEmail author
Part of the Astronomer's Pocket Field Guide book series (ASTROPOC)


Hyginus (8 miles) is a small crater about a ½ mile deep with a flat floor. While not particularly important by itself it is near the center of a remarkable rill named Rima Hyginus. One branch runs northwest from Hyginus and another branch runs to the east. The total length is about 132 miles. I have seen this attractive rill with my 2.4 inch refractor at 120× (6 days after new Moon). There is another rill system, visible on the photo, to the east of Rima Hyginus. This rill is not named on the photo, but it is Rima Ariadaeus. It is nearly the same length as the Hyginus rill.

Triesnecker (16 miles) is a sharp rimmed crater with a central peak. It is 1½ mile deep and the walls are somewhat terraced. There is another system of rills to the east of Triesnecker, running mostly north and south. The deeper rills are visible in my 2.4 inch refractor, but to fully explore the system 6 inches or more of aperture is needed.

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© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Louisville Astronomical SocietyLouisvilleUSA

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