I'm using data from the FERMI SMARTS website, which gives the emissions of blazers. The data has been calibrated using differential photometry (dividing by the average magnitude of a number of reference stars.) "The raw photometry of comparison stars in the field of the blazar was calibrated using photometric zero points ..... correcting for atmospheric extinction derived from all the standards taken together..... the average of the comparison stars was used as a basis of differential photometry with respect to the blazar for all observations" The code I'm using requires inputs of time,flux,error. Therefore I need to convert the data back to flux, my question is can I just use this equation: ma - mb = -2.5log(fa/fb) rearranged as fa/fb=10^(mb-ma/2.5) to get calibrated flux? Thanks in advance!