Neumayer

D=80 km
Center: 71¡S, 71¡E

Count Area: 1561 km^2
Observed Density (@ 1km): 33300 ± 4700
Age: 4.0 ± 0.1 (+sec: 4.1)
Stoffler epoch: Pre-Nectarian
Fit Density (@ 1km): 40000 ± 4400
PF fit: good?, one small D bin and a few large D bins slightly shallow, dominated by secondaries 

Age calculation notes:
- fit anchored at small D. fit improved using Hausen and Holsapple scaling hard rock with a strength of Y=2e7 (SM).
- OK fit (within error for large D) - perhaps could be improved by strength scaling law; adding OSs degrades fit (especially for small craters) and produces older age. Using Hausen and Holsapple strength scaling (SN) improves fit, slightly reduces age (MRK).
- why does using HH scaling work (i.e., including strength)? Including strength causes the PF to become shallower for small craters (transition occurs ~ 1.5 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)? No particular reason to think this surface should be stronger than other craters - has a weathered appearance similar to several other craters. But the transition is at a relatively small D, so perhaps the strength change isn't going to be visible. (MRK)

USGS geology: 
Crater rim mapped as Nectarian. Crater floor mapped as fill with a Nectarian age (ejecta).

Wilhelms: 
Nectarian (all materials)

Floor material: 
Best guess is not original. Relatively flat floor, edges meeting wall look embayed, small central hill(?). Material looks fresh. hard?

Geology Observations: 
Ejecta blanket not visible. Rim eroded. Small central hill (?) that looks very eroded. Some possible wall collapses in NE and SW (excluded). Floor relatively smooth, with a few hummocky areas. Many secondary chains/clusters with various size craters (up to ~ 3.8 km) of mostly degraded classes.

SFD Observations: 
Craters < ~ 1.2 km dominated by class 4. Mid sized craters dominaged by class 3. Largest craters dominated by fresher classes. Has flat SFD for full diameter range. Slope(Diff)=3.6 ± 0.3.

Discussion notes: 
not good candidate for strength - fill is likely ejecta and debris, not hard material => use original fit. dominated by secondaries, not good for PF comparison and age.

Last Edited by MRK 12/17/2012