Far infrared mapping of three Galactic star forming regions: W3(OH), S209 & S187

Three Galactic star forming regions associated with W3(OH), S209 and S187 h ave been simultaneously mapped in two trans-IRAS far infrared (FIR) bands c entered at similar to 140 and 200 mum using the TIFR 100 cm balloon borne F IR telescope. These maps show extended FIR emission with structures. The HI RES processed IRAS maps of these regions at 12, 25, 60 & 100 mum have also been presented for comparison. Point-like sources have been extracted from the longest waveband TIFR maps and searched for associations in the other f ive bands. The diffuse emission from these regions have been quantified, wh ich turns out to be a significant fraction of the total emission. The spati al distribution of cold dust (T < 30 K) for two of these sources (W3(OH) & S209), has been determined reliably from the maps in TIFR bands. The dust t emperature and optical depth maps show complex morphology. In general the d ust around S209 has been found to be warmer than that in W3(OH) region.