basic! introduction to radio/submm interferometry
2014 La Serena School for Data Science Sebastian Perez @ MAD / Universidad de Chile lecture overview ! 1) a bit of HISTORY: radio astronomy / interferometry 2) motivation - why interferometry? 3) basics: interferometers / visibilities / uv-plane 4) imaging 5) deconvolution 6) power of interferometry via 2 cool examples
La Serena School for Data Science / August 2014 For thousands of years human observation of the Universe was limited to the visible spectrum
Until….. Karl Jansky’s serendipitous discovery an engineer of Bell Laboratories, investigating static that interfered with short wave transatlantic voice transmissions. Using a large directional antenna, Jansky noticed that his analog pen-and-paper recording system kept recording a repeating signal of unknown origin. Since the signal peaked about every 24 hours, Jansky originally suspected the source of the interference was the Sun crossing the view of his directional antenna.
Motivation: why interferometry? ! answer: all has to do with diffraction which is the limiting resolution of your telescope. ! ✓ ! ang res ⇡ D ! largest fully steerable radio dish: GBT with 100m dish
$theta = (21e-2/100) * 206265 / 60 = 7.2 arcminutes :(
to reach 1 arc sec resolution you need a 42 km aperture!!
La Serena School for Data Science / August 2014 studied radio signals emanating from the Sun ! ! built the first multi-element astronomical radio interferometer in 1946. ! production of a number of important radio source catalogues, including the Third Cambridge (3C) Catalogue, which helped lead to the discovery of the first Quasar.!
La Serena School for Data Science / August 2014 Motivation: why interferometry? ! there is a need to develop a better technique than just building larger and larger antennas.. ! for an interferometer, resolution is given by