Corrections with measurements of flux

In this part, we present the principal corrections and bias which imply of measurements of flux. The first effect comes from the limited answer of the band-width from the measuring apparatus: the K-correction.

In addition, the presence of interstellar gas cloud in our galaxy and the intergalactic medium involves an attenuation of flux.

Moreover, one certain number of observational biass can intervene. In particular, of the effects of evolution (chemical) which could involve an evolution of the intrinsic luminosity of the objects according to their distance.

Lastly, the limits in term depth of field of the instruments of observations will select for the objects in extreme cases of detection, those whose intrinsic flux is largest with a given magnitude: Malmquist bias .