It' a bug in 2D analytical H2 density in nH.cc . It includes the result from paper "A CO survey of the southern Milky Way - The mean radial distribution of molecular clouds within the solar circle" which assumed the distance between the sun and galactic center is 10 kpc. We need to rescale the parameters \epsilon(R), z_0(R) and z_{1/2}(R) in table 3 according to the method mentioned in Appendix D in that paper.

Thank you for letting us know. We have already implemented a fix that will be included in an upcoming release. The atomic hydrogen distribution was also affected by this.

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Gudlaugur Johannesson, GALPROP developer

Thank for your work!