An infrared portrait of the barred spiral galaxy Messier 83

The image is a false-colour infrared photo of the nearby barred spiral galaxy Messier 83. It is based on the combination of three images obtained in the Ks- (wavelength 2.2 µm), J- (1.2 µm) and I-bands (0.8 µm), respectively. The first two were recorded with the SOFI instrument at the ESO 3.5-m New Technology Telescope , the third with the DFOSC instrument at the Danish 1.54-m telescope, both at the La Silla Observatory.

Technical information: This image of Messier 83 is based on a composite of three images in the filters Ks (NTT + SOFI ; wavelength 2.162 µm; Full-Width-Half-Maximum (FWHM) 0.275 µm; total exposure time on target 49 min; approx. 12 min per quadrant; here rendered as red); J (NTT + SOFI; 1.247 µm; 0.290 µm; 22 min; 5 min; green), and I (Danish 1.54-m + DFOSC ; 0.797 µm; 0.142 µm; 20 min; full-field coverage; blue). As indicated, the Ks and J images were created from exposures of four neighbouring fields. These images were taken in May 2001 during a period with 1.0 arcsec average seeing. The original frames have 1024 x 1024 pixels, each measuring 0.29 arcsec. The resulting mosaic was created from 31 Ks-band object frames and 17 J-band object frames, each with 100 sec exposure time. From each object frame, a sky frame with the same exposure time was subtracted to remove the sky contribution. The final size of the mosaic image is 1905 x 1839 pixels (9.2 x 8.9 arcmin). The I image was observed in February 1998 by Søren Larsen (more information about this image is available in "Astronomy and Astrophysics Supplement", Vol 139, p.393-415, 1999 and at URL: http://nedwww.ipac.caltech.edu/). The original frame size was 2036 x 2042 pixels, each measuring 0.39 arcsec. The pixel size and the field-of-view of this image was changed to match the characteristics of the Ks and J images. North is up and east to the left.