                        Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                                 2024 May 4

                                    3 ATs
       Image Credit & Copyright: Yuri Beletsky (Carnegie Las Campanas
                             Observatory, TWAN)

   Explanation: Despite their resemblance to R2D2, these three are not the
   droids you're looking for. Instead, the enclosures house 1.8 meter
   Auxiliary Telescopes (ATs) at Paranal Observatory in the Atacama Desert
   region of Chile. The ATs are designed to be used for interferometry, a
   technique for achieving extremely high resolution observations, in
   concert with the observatory's 8 meter Very Large Telescope units. A
   total of four ATs are operational, each fitted with a transporter that
   moves the telescope along a track allowing different arrays with the
   large unit telescopes. To work as an interferometer, the light from
   each telescope is brought to a common focal point by a system of
   mirrors in underground tunnels. Above these three ATs, the Large and
   Small Magellanic Clouds are the far, far away satellite galaxies of our
   own Milky Way. In the clear and otherwise dark southern skies, planet
   Earth's greenish atmospheric airglow stretches faintly along the
   horizon.

                   Tomorrow's picture: death by black hole
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
                   NASA Web Privacy, Accessibility Notices
                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

