Ammonia Models ============== The Ammonia modeling tools include a set of constants in the ``ammonia_constants`` module and the following ammonia modeling tools listed below. There is also an ammonia fitter wrapper; see :doc:`wrappers`. Note that there are two modules described here: the multi-rotational-transition fitter, which has its own set of custom functions, and a generic hyperfine-line fitting module meant to fit a single metastable (or non-metastable) transition. If you run into a problem, have a look at the `ammonia-tagged issues on github `__ Note that the default ammonia spectrum, with only the CMB as a background, is intentionally restricted to be positive to avoid nonphysical (absorption against the CMB) parameters. If you find your spectral fits sometimes returning errors about a negative spectrum, you may need the 'restricted excitation temperature' model. In this model, the excitation temperature is no longer a free parameter, but instead is set to trot + deltat, where deltat is a positive value. The only difference from the main ammonia model is this restriction, which can result in more numerically stable results. An example can be found `in the examples directory `__ .. automodule:: pyspeckit.spectrum.models.ammonia :members: .. automodule:: pyspeckit.spectrum.models.ammonia_hf :members: