Occultation Research


We use the method of stellar occultation—an object passing in front of a distant star—to observe objects in the outer solar system, starting with a search for Neptune’s rings in 1983, continuing with Neptune’s moon Triton in 1997, and then a substantial series of observations of Pluto and beyond starting in 2002. By studying the data we obtain during an occultation, we are able to determine the size and probe the atmosphere of these distant objects, gaining insight into their atmosphere’s temperature, density, chemical composition, structure, and other fascinating aspects. To image the events, we use a camera system called POETS (Portable Occultation, Eclipse, and Transit System). More information about POETS and the objects that we study can be found in subsequent pages of this website. More technical information can be found on MIT’s website on occultations: http://occult.mit.edu

This occultation work has almost all been in collaboration with Prof. James Elliot of MIT and his team, especially Dr. Michael Person; the MIT-Williams Consortium keeps in close communication. At Williams, the team includes Prof. Jay M. Pasachoff, Dr. Bryce A. Babcock, and their students. It formerly also included Dr. Steven P. Souza. Pasachoff also collaborated with Prof. Michael Brown of Caltech on studies of the dwarf planet Haumea.

Students who have participated and been or will be co-authors on published papers include:

  • Neptune (Indonesia): Steven Platt ’83
  • Triton (Australia and Hawaii): Timothy McConnochie ’98
  • Pluto (US Hawaii): David Ticehurst ’04
  • Charon (Chile) and Pluto (Australia): Joseph Gangestad ’06
  • Pluto (Australia): Anne Jaskot ’08
  • Pluto (US Southwest): Adam McKay ’08
  • Kuiper belt object 55636 (US Hawaii): Katherine DuPré ’10
  • Pluto (Chile): Muzhou Lu ’13 and Craig Malamut (KNAC ’12)
  • Pluto (US Hawaii): Shubhanga Pandey ’13 and David Amrhein (KNAC ’12)
  • Pluto (New Zealand and US computer work, 2014): Adam Schiff (KNAC ’15) and Tina Seeger ’16
  • Pluto (New Zealand and US computer work): Rebecca Durst ’17 and Tina Seeger ’16
  • Jay Pasachoff’s outreach about the 29 June 2015 occultation by Pluto see more
  • Triton occultation 2017: Ross Yu, Tim Nagle-McNaughton, Connor Marti at Williams: Jay Pasachoff, Christian Lockwood, Allen Davis ’14 at 1-m Embry-Riddle telescope at Daytona; Mike Person (MIT) with the 2.5-m on SOFIA

Occultation research at Williams is supported by NASA Planetary Astronomy Research grant NNX12AJ29G. It is the current successor to NNX08AO50G and NNH04ZSS001N.