GRB 041219A is one of the longest and brightest gamma-ray bursts ( GRBs ) ever observed .
It was discovered by the INTEGRAL satellite , and thanks to a precursor happening about 300 s before the bulk of the burst , ground based telescopes were able to catch the rarely-observed prompt emission in the optical and in the near infrared bands .

Here we present the detailed analysis of its prompt \gamma -ray emission , as observed with IBIS on board INTEGRAL , and of the available X-ray afterglow data collected by XRT on board Swift .
We then present the late-time multi-band near infrared imaging data , collected at the TNG , and the CFHT , that allowed us to identify the host galaxy of the GRB as an under-luminous , irregular galaxy of \sim 5 \times 10 ^ { 9 } M _ { \odot } at best fit redshift of z = 0.31 _ { -0.26 } ^ { +0.54 } .

We model the broad-band prompt optical to \gamma -ray emission of GRB 041219A within the internal shock model .
We were able to reproduce the spectra and light curve invoking the synchrotron emission of relativistic electrons accelerated by a series of propagating shock waves inside a relativistic outflow .
On the other hand , it is less easy to simultaneously reproduce the temporal and spectral properties of the infrared data .