  The core-collapse supernova (CCSN) is considered one of the most energetic
astrophysical events in the universe. The early and prompt detection of
neutrinos before (pre-SN) and during the supernova (SN) burst presents a unique
opportunity for multi-messenger observations of CCSN events. In this study, we
describe the monitoring concept and present the sensitivity of the system to
pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory
(JUNO), a 20 kton liquid scintillator detector currently under construction in
South China. The real-time monitoring system is designed to ensure both prompt
alert speed and comprehensive coverage of progenitor stars. It incorporates
prompt monitors on the electronic board as well as online monitors at the data
acquisition stage. Assuming a false alert rate of 1 per year, this monitoring
system exhibits sensitivity to pre-SN neutrinos up to a distance of
approximately 1.6 (0.9) kiloparsecs and SN neutrinos up to about 370 (360)
kiloparsecs for a progenitor mass of 30 solar masses, considering both normal
and inverted mass ordering scenarios. The pointing ability of the CCSN is
evaluated by analyzing the accumulated event anisotropy of inverse beta decay
interactions from pre-SN or SN neutrinos. This, along with the early alert, can
play a crucial role in facilitating follow-up multi-messenger observations of
the next galactic or nearby extragalactic CCSN.
