  Ultra-hot Jupiters (UHJs) are expected to possess temperature inversion
layers in their dayside atmospheres. Recent thermal emission observations have
discovered several atomic and molecular species along with temperature
inversions in UHJs. We observed the thermal emission spectra of two UHJs
(WASP-33b and WASP-189b) with the GIANO-B high-resolution near-infrared
spectrograph. Using the cross-correlation technique, we detected carbon
monoxide (CO) in the dayside atmospheres of both planets. The detected CO lines
are in emission, which agrees with previous discoveries of iron emission lines
and temperature inversions in the two planets. This is the first detection of
CO lines in emission with high-resolution spectroscopy. Further retrieval work
combining the CO lines with other spectral features will enable a comprehensive
understanding of the atmospheric properties such as temperature structures and
C/O ratios. The detected CO and iron emission lines of WASP-189b have
redshifted radial velocities of several km/s, which likely originate from a
dayside to nightside wind in its atmosphere. Such a redshifted velocity has not
been detected for the emission lines of WASP-33b, suggesting that the
atmospheric circulation patterns of the two UHJs may be different.
