Broadband SED of Ser X-1 constructed with simultaneous data and upper limits from ISGRI (filled diamonds), PICsIT (filled pentagon), JEM-X (filled squares) and ASM data (open square) plus non-simultaneous optical measurements (filled dots), NIR and far-infrared upper limits (open circles and open triangles, respectively) and radio data (filled triangles). Error bars of data points are not reported as their size is comparable to, or smaller than, that of the symbols used in the figure. ...