Robertson

D= 90 km
Center: 22°N, 255°E

Area: 1166 km^2
Observed Density (@ 1km): 9400 ± 2800
Age: 3.7 ± 0.1 (+sec: 3.7)
Stoffler epoch: Late Imbrian
Fit Density (@ 1km): 9000 ± 1000
PF fit: good, one low point for large craters

Age calculation notes:
Good fit (SM).
Fit is OK within error - use as is; adding OSs does not change fit much, but does increase the age (MRK).

USGS geology: 
All mapped as Copernican crater material.

Wilhelms: 
Copernican

Floor material: 
Best guess is original, but some edges near crater rim have sharp boundaries like an embayed feature. Also smooth floor. Hard?

Geology Observations: 
Ejecta blanket visible, but not bright in WAC image. Larger central peak, appears slightly eroded. Hummocky part to floor at 12:00 (ignored). several secondary clusters/chains of moderate size (up to 1.3 km). In context image can see bright ray corresponding to chains on floor - I could not locate source.

SFD Observations: 
Dominated by classes 3 and 4, but 1 & 2 not much lower density. Matches MPF. Steeper distribution. No shallow "right ear" (at least with this binning). Slope(Diff)=-4.2 ± 0.6
Slope(sec)=-3.8 ± 0.9

Discussion notes: 
no issues

Changes suggested by Brian (5/10/2012):
- add some missed class 4 craters and secondaries. Agree with changes (MRK).

Last Edited by MRK 12/17/2012