The Nectarian Period impact event that formed this feature occurred more than 3.8 billion years ago. The mare portion of the basin is about 500 kilometers across. In the grazing sunlight on the floor, wrinkled ridges were visible. Also on the western floor craters Picard (24 km.), Peirce (19 km.) and Swift (11km.) stood out in the low light. I could see the lighter gray bench lava that partly buried craters here such as Yerkes (37 km.). Tall flat top mountains (massifs) beyond the shore stand at 2-5 kilometers above the sea. Both promontoria Lavinium and Olivium stood out clearly in very brief moments.
For this sketch I used: 400 series black Strathmore Artagain paper 9″x 9″, white and black Conte’
pastel pencils , and Conte’crayons, a blending stump, plastic eraser.
Telescope: 13.1 inch f/ 6 Dobsonian with 6mm (332x)
Date: 2-13 & 14-2013 23:00 – 00:45 UT
Temperature: 1.7°C (35°F)
Weather: clear, calm
Seeing: not good Antoniadi IV
Co longitude: 310.9°
Lunation: 3.69 days