N2H+ and HC3N observations of the Orion A cloud

The integral-shaped filament of the Orion A giant molecular cloud was mapped in N2H+, and its nor-them end, the OMC-2/3 region, was also observed in HC3N and CCS. The results were compared with maps of other molecular lines and the dust continuum emission. The N2H+ distribution is similar to the dust continuum distribution, except for the central part of the Orion Nebula. The distribution of (HCO+)-C-13 holds a resemblance to that of the dust continuum, but the N2H+ distribution looks more similar to the dust continuum distribution. The N-bearing molecules, N2H+ and NH3, seem to be more intense in OMC-2, compared with the, (HCO+)-C-13 and CS distribution. This suggests that OMC-2 has a higher abundance of N-bearing molecules, or a higher filling factor of the quiescent gas. We identified 34 cloud cores from N2H+ data. Over the Orion Nebula region, the N2H+ linewidth is large (1.1-2.1 km s(-1)). In the OMC-2/3 region, it becomes moderate (0.5-1.3 km s(-1)), and it is smaller (0.3-1.1 km s(-1)) in the south of the Orion Nebula. On the other hand, the gas kinetic temperature of the quiescent cores observed in N2H+ is rather constant (similar to 20 K) over the integral-shaped filament. We detected no CCS emission in the OMC-2/3 region. In general, the N2H+ and HC3N distribution is quite similar in the OMC-2/3 region, but we observed a displacement between N2H+ and HC3N over a 2' scale in OMC-3, which has a chain of Class 0-I protostars (candidates).