One Jansky represents an incident energy flux density of 10**-26 Watt /m^2/Hz.
The table below gives Jansky equivalents S(nu,0) for a source with magnitude
0.00 in the standard photometric bands.
= 10.5h2 keV cm-3 = 2.78 x 1011 h2 M Mpc-3
= 2 x 10-30 g/cm-3 for h=0.63 OM = 0.3
= 1.3 H-atoms equiv/m-3 for h=0.63 OM = 0.3