Craters Atlas (87 km.) and Hercules (69 km.) make an attractive pair for sketching a few days after full Moon as the terminator slowly approaches. Atlas the older of the two (Upper Imbrium period) was deeper into shadow hiding the fractured floor but not the central floor uplift and peaks. The rims and aprons of both Atlas and Hercules were nicely illuminated as were the surrounding ejecta melts. Hercules the younger of the pair is an Eratosthenian period crater (3.2 billion years old). On the floor of Hercules I could see 14 km. diameter Hercules G near the center of the lava flooded, smooth floor. To the north of Hercules is the 34 km. diameter crater Keldysh with its bowl shape and shadow hidden floor.
For this sketch I used: black Strathmore 400 Artagain paper 10”x 8”, white and black Conte’
pastel pencils and a blending stump. After scanning, Brightness was decreased (-2) and contrast increased (+2) using the scanner controls.
Telescope: 10 inch f/ 5.7 Dobsonian and 4 mm eyepiece 362x
Date: 09-23-2013, 05:30-06:30 UT
Temperature: 14° C (57° F)
Clear, transparent, calm
Seeing: Antoniadi III
Colongitude 128.5 °
Lunation 17.6 days
Illumination 86.1 %