The images from the SDSS project are organized into stripes.
These are long images, 24,000 pixels wide (2.5 degrees), and typically
over 1 million pixels long (120 degrees). The SDSS covers the northern
sky with 45 overlapping stripes. The stripes try to avoid the dust in
the plane of the Milky Way, as shown by the red areas on the celestial
sphere to the right.
Each stripe is merged from two runs, taken on separate nights.
The telescope can complete only a single run in any given night: it takes
about 8 hours to complete one. Each run consists of 6 camcols
(camera columns), one corresponds to each array of CCD detectors of our
camera. Each camcol takes images in five colors.