Joule

D=98 km
Center: 27¡N, 216¡E

Count Area: 1053 km^2
Observed Density (@ 1km): 31300 ± 5500
Age: 4.0 ± 0.1 (+sec: 4.1)
Stoffler epoch: Pre-Nectarian
Fit density (@ 1km): 49900 ± 6900
PF fit: good*, all craters within error, small area (~ 1000 km2)

Age calculation notes:
- poor fit - fit anchored at large D. Fit improved to good with layering with thickness H=0.20km. the top layer has Y=2e7, the bottom layer has Y=2e8 (SM).
- good fit to large D - bad fit to small D - maybe geology, but worth trying strength scaling law or layer?; adding OSs slightly improves fit and produces older age. Fit improved using layering (LrN), age decreases slightly (MRK).
- why does using layering work? Including a change in strength causes the PF to kink and shift for small D (transition occurs D ~ 1 km), which is why the fit is better. But is there justification for using this law here and not with other craters (i.e., is geology different)? The surface does have a weathered look, but can see small areas that look more "solid". There is one partially filled larger crater indicating a thin layer of fill (which see in other layers w/o kink). So a thin "weak" layer over a stronger layer is not unreasonable. Note a resurfacing event that removes small craters preferentially can produce the same effect and terrains of two ages. Although a region of of lower small crater density does not pop out. (MRK)

USGS geology: 
Crater mapped as Nectarian. Small areas of floor material mapped as fill with Imbrian to Nectarian age (corresponds with counting area).

Wilhelms: 
Crater is Nectarian. Perhaps a little fill with Orientale ejecta (Early Imbrian)?

Floor material: 
Best guess is not original for areas counted. Flatter floor, material has contacts with wall/peak that look embayed, fill in larger crater on the floor, small central peak. Material looks softened. Loose?

Geology Observations: 
Ejecta not visible(see ejecta, but likely from the nearby younger craters?). Rim is eroded (especially to south - landed on another crater?), but has a little sharpness on east side. Small central peak that looks heavily eroded. Floor has low hummocks (maybe original floor or collapses) with some smooth areas (smooth areas counted). A few secondary chains/clusters with various sized craters (up to ~ 2 km) - mostly degraded.

SFD Observations: 
Craters < ~ 2 km dominated by class 4. Largest craters dominated by class 3. Classes 1 and 2 lower in density. Has flat SFD for full diameter range. Slope(Diff)=2.9 ± 0.3.

Discussion notes: 
Change floor "possibly" to "not likely"

Notes from Brian's adjustment:
- Counting boundary:
	Irregular, but might be OK. A bit iffy near 6:00.
	Some missing type 4's.

- Secondaries:
	One cluster missed at 7:30, another in the center.

- Removal of large, buried craters:
	The large crater at 6:00 depends on whether the boundary is changed.

- Size adjustment of large craters:
	The large crater at 6:00 should be slightly larger.

- Explaining unusual cases:

- Future actions:

- Completed actions:
	Changed the boundary (Michelle).
	Add some type 4 craters and clusters (BLE).
	Altered a few classifications (MRK).

Last Edited by MRK 12/13/2012