0.01 5×10 −3 0.02 0.05 normalized counts s −1  keV −1 PKS 2052−47 1 0.5 2 5 0 0.02 residuals Energy (keV) 2009 Fermi Symposium, Washington, D.C., Nov. 2-5 3 Figure 3: Fermi LAT pre-flare light curve of PKS 2052 − 47 from 4 th August 2008 to 4 th July 2009. This plot shows the light curve since Fermi’s launch, binned to one week. The x-axis is time in the unit of mission elapsed time (MET), and the y-axis is the energy flux between 100 MeV–100 GeV in units of photon cm − 2 s − $^{1}$. Figure 2: Swift XRT spectrum of PKS 2052 − 47 in the 0.3 − 6 keV energy range with 2.5 ks integration observed on September 6, 2009. The fitted model (solid line, upper panel) is an absorbed power-law. The residual of fit is shown in the lower panel. 10 6 10 7 10 8 10 9 10$^{10}$10$^{11}$10$^{12}$10$^{13}$10$^{14}$10$^{15}$10$^{16}$10$^{17}$10$^{18}$10$^{19}$10$^{20}$10$^{21}$10$^{22}$10$^{23}$10$^{24}$10$^{25}$10$^{26}$10 27 10 10 11 10 12 10 13 10 14 10 15 10 16 10 17 10 18  Frequency (Hz) I  × Frequency (mJy·Hz) Figure 4: The broadband SED of PKS 2052 − 47. Black filled pentagons: simultaneous data from our multiwavelength campaign triggered in September 2009, which includes APEX preliminary data, Swift UVOT/XRT, and Fermi LAT data. Red open circles: historical data from the NASA extragalactic database (NED), including the EGRET detection. The highest energy bin of LAT data (right-most filled pentagon) has an error bar which has the same order of magnitude as the flux density value. eConf C091122