# How to get the zeropoint magnitude?

I'm working with some data and I have some values named fluxmag0 and fluxmag0err that should correspond to the zero point values and error in flux units.

The values are around $10^{13}$ for fluxmag0 and $10^9$ for fluxmag0err

I need to have the zero point error in magnitude units. If I take $2.5\log_{10}(\mathrm{fluxmag0err})$ the values are huge so I suppose it's not the way to compute this.

How can I convert these values in terms of magnitudes?

Thanks a lot in advance for your help

Magnitude is defined relative to a standard flux of a magnitude 0 object $F_0$.
$$M = -2.5\log(F/F_0)$$
if the error is $F_E$, then $F =F_0\pm F_E$, so the magnitude M is
$$-2.5\log((F_0+F_E)/F_0) < M <-2.5\log((F_0-F_E)/F_0)$$