Infrared wide angle view of RCW 108

Image showing a unique, wide-field infrared view of the region around IRAS 16362-4845, an "emission" nebula that shines by its own light. It is situated within a dark cloud in a Milky Way region (the "RCW 108 complex") at a distance of about 4,000 light-years in the direction of the Southern constellation of Ara (the Altar). The dark cloud is seen silhouetted against the rich background of stars in the Milky Way, whose light is blocked by the dust particles in the cloud. The photo is based on approx. 600 individual exposures with the SOFI instrument at the 3.58-m ESO New Technology Telescope (NTT). The field-of-view measures about 13 x 13 arcmin^2, coresponding to 17 x 17 light-years^2.

Technical information: this image was obtained in February 2000 by means of SOFI, the infrared camera and spectrograph at the ESO 3.58-m New Technology Telescope (NTT). The image is a mosaic that was prepared by combining 33 overlapping frames, taken in each of the J (wavelength 1.25 µm; here rendered as blue), H (1.65 µm; green) and K (2.2 µm; red) infrared filters. Each individual frame is in turn a stack of six frames totaling 12 sec exposure time, with the exception of the one covering the center of the region which is 15 times longer in order to increase the sensitivity around the central emission nebula (an HII region). The total area imaged is 12.8 x 12.8 arcmin^2, using SOFI in its normal resolution mode with 0.29 arcsec pixels and a field of about 5 arcmin. Thus the field shown here is about 6.6 times the field-of-view in a single SOFI frame. Five-sigma detection limits in the least-exposed areas of the image are typically J=18.6, H=17.7, K=17.2 mag. The image quality is between 0.6 and 0.7 arcsec for the different filters over most of the field. North is up and East is left.