  G4.8+6.2 was proposed as a possible kilonova remnant associated with the
Korean guest star of AD 1163 in our Milky Way galaxy. Its age is about 860
years according to the historical record. If a neutron star was left in the
center of G4.8+6.2, this young neutron star may radiate strong continuous
gravitational waves, which could beat the indirect age-based upper limit with
current LIGO sensitivity. In this work, we searched such continuous
gravitational waves in the frequency band $20-1500 \mathrm{~Hz}$. This search
used two days of LIGO O3b data from the Hanford and Livingston detectors. While
no signal was found, we placed upper limits on the gravitational wave strain.
For comparison, we also showed the latest results of all-sky searches obtained
with various search pipelines. With upgrading of the gravitational wave
detectors, it will provide the opportunity to see whether a black hole or a
neutron star is harbored inside G4.8+6.2.
