  In this paper we place new constraints on a f(R) modified gravity model
recently proposed by Hu and Sawicki. After checking that the Hu and Sawicki
model produces a viable cosmology, i.e. a matter dominated epoch followed by a
late-time acceleration, we constrain some of its parameters by using recent
observations from the UNION compilation of luminosity distances of Supernovae
type Ia, including complementary information from Baryonic Acoustic
Oscillations, Hubble expansion, and age data. We found that the data considered
is unable to place significant constraints on the model parameters and we
discuss the impact of a different assumption of the background model in cosmic
parameters inference.
