Lambert crater is a smallish complex crater of 30 kilometers diameter resting on the floor of Mare Imbrium. This Eratosthenian crater must be some 2.5 billion years old. Its outer rampart is impressive, as is its floor, which unfortunately was not seen on this occasion due to morning shadowing.The ghost crater Lambert R was detectable but is best seen closer to the terminator as sunset approaches during the waning crescent phase. Further south from Lambert and Lambert R, crater Pytheas (20 km.) was also visible. Closer to the sunrise terminator Mons La Hire was casting long shadows while crater Euler (29 km) was just catching light on its eastern rim.
To the north of Lambert, Dorsa Stille and Dorsum Zirkel were easily visible along with many small craters.
Lambert crater on ebony black Canson paper using white and black Conte’ pastel pencils
Sketch Date: April 13, 2011, using a 10 inch f/5.7 Dobsonian telescope riding on an equatorial platform with a 6mm eyepiece for 241x at 03:00-04:10 UT
Seeing: Antoniadi III
Weather clear, calm, 50 degrees F (10 degrees C)
Lunation 9.5 days
Moon 67.9% illuminated
Rükl Atlas Pl 20