Catharina, Cyrillus and Theophilus
Sketch and Details by Frank McCabe
If you have not observed this trio through a telescope then you are in for a treat when you do. The trio I speak of is Catharina, Cyrillus and Theophilus. All three of these craters are between 100 and 104 kilometers in diameter. The oldest of the three is Catharina which is also the southern most of the group in this north at the bottom sketch. Catharina, a Nectarian period impact may be older than the Imbrium basin with debris from that basin scattered across this crater and the older surroundings. Cyrillus a bit younger than the former shows terraced walls and worn central peaks. The last member of the trio is one of those lunar treats that cannot go unnoticed. Theophilus, an Eratosthenian crater, just about has it all. It is large, sharp rimmed, terraced walled, tall central peaks (2 km.), a flat floor, and much melted ejecta just beyond the crater especially to the north and east. The outer reaches of Theophilus gradually merge with the Bay of Asperity.
To the east 28 km Mädler can be seen disappearing into the shadows approaching from the left as they cross the Sea of Nectaris.
Sketching:
For this sketch I used: black Strathmore 400 Artagain paper, white and black Conte’ pastel pencils, Conte’ crayons and a blending stump. After scanning, Brightness was slightly decreased (-2) and contrast increased (+4) using Microsoft Office Picture Manager.
Telescope: 10 inch f/ 5.7 Dobsonian and 9 mm eyepiece 161x
Date: 6-23-2008, 7:30-8:50 UT
Temperature: 15° C (59° F)
Clear, transparent, calm
Seeing: Antoniadi II
Colongitude 147.9 °
Lunation 19.5days
Illumination 81 %
Frank McCabe