Sirius A has an apperant magnitude of -1.5, and his distance from us is 2.6 pc. the sun has an apperent magnitude of -26.8 and a distance of 1 AU. what is Sirius's absolute magnitude? how meny times is Sirius brighter then the sun? m1-m2=-2.5lg(f1/f2) this is the equation i'm supposed to use, its the one they gave me. i think it is much more oppropriate to use: m-M=5lg(d)-5 and then just dividing to find how much brighter he is. so, what unit does the distance "d" needs to be in? and how do i calculate the answers with the first equation? and what is flux? i couldnt get a clear explanation anywhere.