The first source catalog of the Large High Altitude Air Shower Observatory (LHAASO) reported the detection of a very high energy gamma-ray source, 1LHAASO J1219+2915. This Letter presents a further detailed study of the spectral and temporal behavior of this pointlike source. The best-fit position of the TeV source (R. A. = 185°. 05 ± 0°. 04, decl. = 29°. 25 ± 0°.03) is compatible with NGC 4278 within ∼0°.03. Variation analysis shows an indication of variability on a timescale of a few months in the TeV band, which is consistent with low- frequency observations. Based on these observations, we report the detection of TeV γ-ray emissions from this low-luminosity active galactic nucleus. The observation by LHAASO's Water Cherenkov Detector Array during the active period has a significance level of 8.8σ with a best-fit photon spectral index Γ = 2.56 ± 0.14 and a flux $f_{1–10 TeV]$ = (7.0 ± 1.1sta ± 0.35syst) × 10−13 photons cm−2 s−1 , or approximately 5% of the Crab Nebula. The discovery of VHE gamma-ray emission from NGC 4278 indicates that compact, weak radio jets can efficiently accelerate particles and emit TeV photons.
