deletions | additions       diff --git a/Now_its_time_time.tex b/Now_its_time_time.tex  index 906862e..8dc3707 100644  --- a/Now_its_time_time.tex  +++ b/Now_its_time_time.tex 
...
f = 2.51^{-m + c}  \label{eq:fluxcalib}  \end{equation}  where $c$ is a constant which we're going to determine. In astronomy, this equation is usually rearranged to give:  \begin{equation}  m = -2.5\log(f) + c.  \end{equation}  Derive this form.  For two sources, the difference in their magnitudes is then  proportional to the ratio of their fluxes:  \begin{equation}