Lights Out for Eratosthenes

   At the southern end of the lunar Apennines on the border between the Bay of
Billows (mostly in darkness) and Sea of Rains lies 60 km. crater Eratosthenes. I
was off and on observing over most of the night. By morning twilight when the moon
was high in the east, Eratosthenes crater was experiencing sunset. The deep, dark
caldera-like aperture was undergoing sunset at the beginning of my sketch. This
3.2 billion year old land mark crater is the defining feature of the Eratosthenes
time period. While sketching I could clearly see much of the ejecta pitting of
Copernicus and its ray material which crossed the region 2 billion years after
Eratosthenes formed. I did not include much of the Copernicus crater impact
features because they are in my opinion more suitable for high resolution
photography or direct visual examination at high power. In this sketch I tried to
briefly capture the overall eyepiece view.
  
  
  Sketching:
  For this sketch I used: black Strathmore 400 Artagain paper, white and black Conte’
  pastel pencils and a blending stump. Contrast was slightly increased after scanning.
  Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241X
  Date: 7-8-2007, 9:15-10:30 UT
  Temperature: 22° C (73° F)
  Clear to partly cloudy, light winds
  Seeing:  Antoniadi II
  Colongitude 190.2 °
  Lunation 23.25 days
  Illumination 42.2 %
  
  Frank McCabe