Distribution of cold dust in Orion A and B

Large-scale far-infrared (FIR) observations of the Orion complex at 205 and 138 mu m are presented with the aim of studying the distribution of cold (<25 K) dust. The maps in these FIR bands extend over similar to 3600 arcmin(2) and cover regions around OMC-1, 2, and 3 in Orion A and NGC 2023 and NGC 2024 in Orion B. Some limited regions have also been mapped at 57 mu m. A total of 15 sources in Orion A and 14 in Orion B (south) have been identified from our FIR maps. Dust temperature distribution in both Orion A and Orion B (south) have been determined reliably using the maps at 205 and 138 mu m obtained from simultaneous observations using almost identical beams (1.'6 diameter). These temperatures have been used to generate the map of tau(150), the optical depth at 150 mu m for the Orion B region, The coldest source detected is in OMC-3 and has temperature similar to 15 K. The diffuse FIR emission in the different subregions is found to vary between 25% and 50% of the total FIR emission from that subregion.