am is a tool for radiative transfer computations at microwave to submillimeter wavelengths. Spectra which can be computed with am include thermal emission, absorption, transmission, and excess delay. The program can modify computed spectra to model the response of spectrometers and receiving systems, and can compute Jacobians of output spectra differentiated with respect to selected model parameters. Measured spectra can be fitted using a simple scheme for flagging model parameters as fit variables.

The primary application area for am is in radio astronomy, involving terrestrial propagation paths between ground and sky. The program can also be applied to a variety of other radiative transfer problems, and has been used for applications ranging from laboratory receiver testing to radio spectrum management.

Download the latest version of am.

SMA memo #152 is the manual for am. (To cite am, please use the permanent DOI for the manual.)

The am cookbook is a collection of application example files.

Browse the am source code here.