Firefly (Fitting IteRativEly For Likelihood analYsis): a full spectral fitting code

Understand

We present a new spectral fitting code, Firefly, for deriving the stellar population properties of stellar systems.

• Firefly is a chi-squared minimisation fitting code that fits combinations of single-burst stellar population models to spectroscopic data, following an iterative best-fitting process controlled by the Bayesian Information Criterion.
• No priors are applied, rather all solutions within a statistical cut are retained with their weight.
• Moreover, no additive or multiplicative polynomia are employed to adjust the spectral shape.