CBJ October 2010

File EarthImpactDatabase contains all the data from the EID.

eid_age.dat was generated from EarthImpactDatabase using an Emacs macro to retain just the ages, and was edited by hand.
The original table, CINameSort2.htm, attaches "*" to some dates which indictate a different dating method:

"pre-1977 K-Ar, Ar-Ar and Rb-Sr ages recalculated using the decay
constants of Steiger and Jager (1977) Ages in millions of years (Ma)
before present."

eid_diameter.dat was generated from EarthImpactDatabase using an Emacs macro to retain just the diameters.
Four entries were modified:
Two entries had "~". This symbol was removed.
One had range 6-13, so I replaced it with its average
One said "4.5 by 1", so I swapped this for the diameter of the circle with the same area: D=sqrt(4.5 * 4/pi)=2.4.

Data sets eid_setX.dat generated by plot.R

set1:	  87 craters with sd estimate, age<=700Myr 
set2:	  61 craters with sd estimate, age<=700Myr, D>= 5km
set3:	  42 craters with sd estimate, age<=250Myr, D>= 5km
set4:	  32 craters with sd estimate, age<=150Myr, D>= 5km
set5:	  18 craters with sd estimate, age<=400Myr, D>=35km 
set6:	  35 craters with sd estimate, age<=250Myr, D>= 5km, sd(age)<=10Myr

set3ext:  46 craters; as set3 but including 4 craters with generated age uncertainties
set4ext:  36 craters; as set4 but including 4 craters with generated age uncertainties 

set3lim:  59 craters; set3ext but including the 13 craters with upper age limits up to 250Myr
          D/km = 5.1 6.0 6.0 6.0 9.0 9.5 10.0 10.0 12.0 13.0 13.0 18.0 52.0
set4lim:  48 craters; set3ext but including the 12 craters with upper age limits up to 150Myr

Origin of set3ext and set4ext (points with age uncertainties given as "A", "N" or "R")
- set3 and set4 include two craters younger than 5 Myr, at 0.9±0.1 and 3.5±0.5 Myr (and two at 5Myr).
- there are two craters with age<250Myr with ages with age uncertainty label "A" (see eid_age.dat). 
  These have ages 0.27Myr (D=0.024km) and 0.0066Myr (D=0.08km)
- there are four craters with age<250Myr with ages with age uncertainty label "N". 
  These have ages 0.00014Myr (D=0.116km), 0.00063Myr (D=0.027km), 1.07Myr (D=10.5km) and 39Myr (D=23km)
- Thus of the data with "N" and "A" age uncertainties, only two should be considered for the age<250Myr, D>5km samples
  namely Bosumtwi (1.07Myr, D=10.5km) and Haughton (39Myr, D=23km).
  Craters with age<=50Myr have dating errors ranging from 0.1Myr to 20Myr, or a fraction of 0.003 to 0.6.
  So assuming a fractional error of 0.1 in these is probably okay. Ages are then 1.07±0.107Myr and 39±3.9Myr.
- Two craters with age<250Myr and D>5km have age uncertainty R. They are Jebel Waqf as Suwwan (37-56Myr, D=5.5km) 
  and Avak (3-95Myr, D=12km). I interpret the age range as a 90% CI (3.29sigma), and the mean as the average, so I assign these two
  ages of 46.5±5.8Myr and 49.0±28.0Myr
=> add four craters to set3 and set4 and call these set3ext and set4ext:
    1.07  0.107
   39.0   3.9
   46.5   5.8
   49.0  28.0

set6 is basically pointless, as artmod3 takes into account errors. But it's for test/comparison purposes.

