x         y       sigma
    0.2926    2.1974    0.8329
    0.3810    2.4527    0.2945
    0.4257    2.9327    0.8603
    0.4728    3.2492    1.4081
    0.8355    3.6453    0.7233
    1.2653    6.6705    1.0508
    1.4561    7.8816    0.8661
    1.6406    9.6005    0.2479
    1.8971   12.3137    0.6063
    2.3766   16.5465    0.0424
    2.4008   15.9377    0.9630
    2.4442   17.2783    0.2582
    2.7174   20.2614    0.2113
    2.7401   20.7412    0.0557
    2.7472   20.8832    1.3366
    2.8715   24.4736    1.2930
    2.8725   22.0241    0.6251
    2.8785   22.5920    0.0230
    2.8947   22.5145    1.2522
    2.9118   23.6907    0.5969