A raw image straight from the VISIR instrument on the VLT

As the instrument observes in the thermal infrared, the individual exposures are extremely short, and the final image are obtained by combining hundreds, or even thousands, or individual snapshots obtained at slightly different positions. This technique allows the astronomers to beat the incredibly bright background from the sky and from the telescope itself, as it emits brightly at these wavelengths. It also allows them to correct for the many defects of the tiny detector, which appear here as dark and bright spots, as well as structure in the background. This image was one of the many that was used to produce an impressive view of the nebula around the bright star Betelgeuse.