Spectral energy distribution of the Sw J1644+57 event as modeled in Burrows et al. (2011). The black curve is the modeled SED around the peak of the X-ray flares (~31 h after event onset) with and without flux suppression by pair production (solid and dashed lines, respectively). The gray curve shows the corresponding model in the low X-ray flux state at ~5.5 days after the trigger. Black circle data points are the XRT and BAT fluxes as measured few days after the BAT trigger; diamond points show the measured SED at 4.5 days, while triangle data points are XRT data between 6.5 and 9.5 days after the BAT trigger. The black arrows represent the ULs derived from the MAGIC observations that are presented in this work (Table 1). The down-pointing black and gray triangles in the VHE range are the VERITAS UL observations for the total and flaring period. In the HE range, AGILE upper limits in the 50–200 MeV (gray square) and >100 MeV (black square) are reported for an integration time of 5 and 2 days (this work). The Fermi-LAT limit between March 28 to April 4 (star UL) is also reported. In the optical range, K-band data form the Telescopio Nazionale Galileo (TNG) from about 2.5 days (open square) and 4.5 days (star) after the onset are shown.