Placing a radiation source (e.g.

*star*) at the standard distance of 10*parsecs*, it follows that the zero point of the apparent bolometric*magnitude*scale m bol = 0 corresponds to irradiance f 0 = 2.518021002 W/m 2. Using the IAU 2015 scale, the nominal total*solar*irradiance ("*solar*constant") measured at 1*astronomical**unit*(1361 W/m 2) corresponds to an apparent bolometric*magnitude*of the*Sun*of m bol,⊙ = −26.832.