astropy/astropy — pull request #1629 by larrybradley (2013-10-22 02:33:12+00:00)
Title: Fixed sign of MexicanHat1DModel and MexicanHat2DModel

Mexican hat kernels should have positive cores with negative wings. Not sure why the kernels were inverted from the MexicanHat(1/2)DModel.