Error weighting?	Yes No
Propagate external error?	Yes No
Maximum Likelihood?	Yes No
Include Sm?	Yes No
Precision:
Single grain ages:	significant digits
Geometric mean composition:	significant digits
Central age:	significant digits

Central age calculator
U - σ(U) - Th - σ(Th) - He - σ(He)	t - σ(t)
588.19 6.86 451.29 7.02 12.48 1.88 874.38 7.55 628.05 11.11 13.23 1.99 294.29 3.51 156.39 2.56 5.47 0.83 595.94 7.69 260.26 4.29 8.73 1.32 645.15 8.40 370.18 6.97 9.46 1.42 867.17 8.86 374.24 5.00 12.44 1.87 221.88 2.60 163.49 2.80 3.10 0.48 225.88 2.34 136.26 2.01 2.99 0.46 131.12 1.98 130.26 2.04 3.38 0.52 356.95 6.77 203.52 4.60 8.11 1.22 106.96 1.51 126.01 2.43 1.60 0.26

From left to right and from top to bottom, the four text boxes contain the following information: Input: either 6 columns of data [U, σ(U), Th, σ(Th), He, σ(He)], or 8 columns of data [U, σ(U), Th, σ(Th), Sm, σ(Sm), He, σ(He)] separated by spaces, tabs, commas or semi-colons. These data can be copied and pasted from Excel. A consistent set of measurement units (e.g., fmol or fmol/g) must be used for all elements. Helium, or U, Th, and Sm must be α-ejection corrected prior to age calculation. Output: single-grain ages and 1-σ analytical uncertainty, in Ma. Output: geometric mean composition and 1-σ analytical uncertainties, normalized to unity. Output: central age and 1-σ analytical uncertainty, in Ma. Alternatively, arithmetic and geometric mean ages as well as central ages can be calculated with a Maximum Likelihood algorithm using the HelioPlot program, which also plots U-Th-(Sm)-He data on ternary diagrams and logratio plots.