  MAXI/GSC detected a superburst from EXO 1745-248 in the globular cluster
Terzan 5 on 2011 October 24. The GSC light curve shows an exponential decay
with an e-folding time of 0.3 day. The spectra are consistent with the
blackbody radiation, whose temperature is 2.2 keV and 1.2 keV at MJD 55858.56
and 55859.20, respectively. The fluence is $1.4 \times 10^{42}$ erg in 2-20 keV
assuming 8.7 kpc distance. The sphere radius of the blackbody and its
luminosity are estimated to be 6.2 km and $1.1 \times 10^{38}$ erg s$^{-1}$,
respectively, from the spectral fitting at the flux peak. Those e-folding time,
temperature, softening, fluence, and radius are typical of superbursts from the
low-mass X-ray binaries. The superburst was followed by an outburst 28 hours
after the superburst onset. The outburst lasted for 5 days and the fluence was
$4.3 \times 10^{42}$ erg. The instability of the accretion disk caused by the
superburst would be an explanation for the outburst, whereas the mass accretion
of the matter evaporated from surface of the companion star by the superburst
would be another possibility.
