How do we calculate the magnitude of a system with binary stars?

[VHCR]

How do we calculate the magnitude of a system composed by some binary systems of stars?

 

[cepheid]

You need to give us more information. *Some* binary systems? How many? Just one binary, or multiple binaries?

Do you know the magnitudes of the individual stars in the binary or binaries?

 

[VHCR]

Yeah, suppose we know the magnitude of all the stars and that the number of binary systems is k (can be one or more).