Axel Mellinger’s All-Sky Milky Way Panorama 2.0
Between October 2007 and August 2009, a new digital all-sky mosaic image was assembled from more than 3000 individual CCD frames. Using an SBIG STL-11000 camera, 70 fields (each covering 40° × 27°) were imaged from dark-sky locations in South Africa, Texas and Michigan. In order to increase the dynamic range beyond the 16 bits of the camera’s analog-to-digital converter (of which approx. 12 bits provide data above the noise level), three different exposure times (240 s, 15 s and 0.5 s) were used. Five frames were taken for each exposure time and filter setting. The fields were photometrically calibrated using standard catalog stars and sky background data from the Pioneer 10 and 11 space probes. The new panorama has an image scale of 36 arcsec/pixel (approx. 3× the resolution of the old, film-based mosaic), a limiting magnitude of approx. 14 mag and an 18 bit dynamic range. At full resolution and bit depth, it is a 648 MPixel, 7.7 GByte FITS cube. Unlike the old image, the new panorama was carefully calibrated to preserve the large-scale star and dust clouds.