  We present the serendipitous detection of a new Galactic Supernova Remnant
(SNR), G288.8-6.3 using data from the Australian Square Kilometre Array
Pathfinder (ASKAP)-Evolutionary Map of the Universe (EMU) survey. Using
multi-frequency analysis, we confirm this object as an evolved Galactic SNR at
high Galactic latitude with low radio surface brightness and typical SNR
spectral index of $\alpha = -0.41\pm0.12$. To determine the magnetic field
strength in SNR G288.8-6.3, we present the first derivation of the
equipartition formulae for SNRs with spectral indices $\alpha>-0.5$. The
angular size is $1.\!^\circ 8\times 1.\!^\circ 6$ $(107.\!^\prime 6 \times
98.\!^\prime 4)$ and we estimate that its intrinsic size is $\sim40$pc which
implies a distance of $\sim1.3$kpc and a position of $\sim140$pc above the
Galactic plane. This is one of the largest angular size and closest Galactic
SNRs. Given its low radio surface brightness, we suggest that it is about 13000
years old.
