Coulomb

D=90 km
Center: 54°N, 245°E

Count Area: 2030 km^2
Observed Density (@ 1km): 8900 ± 2100
Age: 3.7 ± 0.1 (+sec: 3.7)
Stoffler epoch: Late Imbrian
Fit Density (@ 1km): 8100 ± 1300
PF fit: good, large craters deviates from line, but within error

Age calculation notes:
Bad fit for large D, good for small D (SM).
Fit is good for small D and not that bad for large D within error (this SFD does have "right ear") - use as is; adding OSs does not change fit or age (MRK).

USGS geology: 
Crater rim mapped as Nectarian. Crater floor mapped as fill with a Late Imbrian age.

Wilhelms: 
Nectarian (all materials)

Floor material: 
Best guess is not original. Very smooth flat floor, edges meeting wall are sharp and look embayed, no central peak. Also surrounded by other craters filled with mare. Material looks fresh. Hard?

Geology Observations: 
Ejecta blanket very eroded and embayed by mare (?). Rim looks eroded. No central peak. Floor flat. Only a few secondary chains/clusters with small craters (up to ~ 1.3 km).

SFD Observations: 
Craters dominated by classes 3 & 2. Class 4 craters high density for small craters (0.6-0.8). Distribution < 1.5 km steep. Shallow "right ear" (more than 1 crater!). Slope(Diff) = 5.3 ± 0.5.

Discussion notes: 
Is "v" real feature, maybe not for this one, class 3 crater may be buried, which really leaves only one crater

Questions by BLE 5/9/2012:
- Perhaps recheck the cluster craters? Some marked clusters look iffy.
- The marking boundary could perhaps be shrunk just a wee bit around the 5:00
  position?
I'm thinking both of these are OK the way they currently are (MRK)

Last Edited by MRK 11/18/2012