The program AVSINI may be used to apply rotational broadening to a synthetic spectrum. AVSINI will prompt the user for the required inputs, or it may be used in a command line mode. The format for invoking AVSINI in the command line mode is
avsini input output vsini u dlambdawhere input is the filename of the synthetic spectrum you wish to rotationally broaden, output is the name of the rotationally broadened spectrum, vsini is the rotational velocity, in km/s, u the limb-darkening coefficient (0.6 is a good value to use here, but see Gray, 2008) and dlambda is the wavelength spacing in the input file. The spacing in the output file will be the same as the spacing in the input file. If used in the prompt mode, the AVSINI prompts are in the same order. Rotational broadening should be carried out before the spectrum is smoothed to a lower resolution with SMOOTH2. AVSINI may be used either before or after macroturbulent broadening is applied (see below). AVSINI is designed to be used with ascii synthetic spectra. The program VSINI is the equivalent to be used with binary synthetic spectra. Both programs use David Gray's (Gray, 2008) implementation of rotational broadening.