Molecular emission of 13CO (J=1−0) and C18O (J=1−0) from OMC-3

13CO (J = 1 − 0) and C18O (J = 1 − 0) emissions of the OMC-3 in the Orion A molecular cloud were mapped with the 13.7 m millimeter wave telescope of Purple Mountain Observatory using a higher spatial resolution. The overall structure of the cloud and the average physical parameters of all the 13CO (J = 1 − 0) and C18O (J = 1 − 0) cores are derived. We find that the cores are well associated with the youngest objects — class 0 sources: MMS1, MMS4, MMS6 with the 13CO core centers and MMS7, MMS8, MMS9 with the C18O core centers. The velocity structure is also analyzed for the whole OMC-3 region. There is a ∼ 1.7 km/s velocity gradient from south to north connecting the 13CO (J = 1 − 0) and C18O (J = 1 − 0) cores. And the redshifted clumps are consistently to the north, and the blushifted clumps, to the south of OMC-3. Star formation in the region is also discussed.