... Planck

http://www.rssd.esa.int/index.php?project=planck

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...)

http://lca.ucsd.edu/portal/software/enzo

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... RECFAST

http://www.astro.ubc.ca/people/scott/recfast.html

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... temperatures

Note that this does not introduce a significant error, as owing to its exponential dependence on temperature, rate 27 is tiny at $T < 2.5 \: {\rm K}$.

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... Telescope

http://pole.uchicago.edu/

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... Telescope

http://www.physics.princeton.edu/act/

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... Fig. B.2.b)

Note the discrepancy with SLD98, who find a rate for the proton transfer reaction of ${\rm HeH}^+$ which is larger by a factor of 1.5.

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