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Pluto Occultation on 2015 June 29 UTC With Central Flash and Atmospheric Spikes Just Before the New Horizons Flyby

Pasachoff, Jay M. and Babcock, Bryce A. and Durst, Rebecca F. and Seeger, Christina H. and Levine, Stephen E. and Bosh, Amanda S. and Person, Michael J. and Sickafoose, Amanda A. and Zuluaga, Carlos A. and Kosiarek, Molly R. and Abe, Fumio and Nagakane, Masayuki and Suzuki, Daisuke and Tristram, Paul J. and Arredondo, Anicia (2017) Pluto Occultation on 2015 June 29 UTC With Central Flash and Atmospheric Spikes Just Before the New Horizons Flyby. Icarus, 296 . pp. 305-314. ISSN 0019-1035.

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We observed the occultation by Pluto of a 12th magnitude star, one of the two brightest occultation stars ever in our dozen years of continual monitoring of Pluto's atmosphere through such studies, on 2015 June 29 UTC. At the Univ. of Canterbury Mt. John Observatory (New Zealand), under clear skies throughout, we used a POETS frame-transfer CCD at 10 Hz with GPS timing on the 1-m McLellan telescope as well as an infrared camera on an 0.6-m telescope and three-color photometry at a slower cadence on a second 0.6-m telescope. At the Auckland Observatory, we used a POETS and a PICO on 0.5-m and 0.4-m telescopes, with 0.4 s and 2 s cadences, respectively, obtaining ingress observations before clouds moved in. The Mt. John light curves show a central flash, indicating that we were close to the center of the occultation path. Analysis of our light curves show that Pluto's atmosphere remains robust. The presence of spikes at both sites in the egress and ingress shows atmospheric layering. We coordinated our observations with aircraft observations (Bosh et al., 2017) with the Stratospheric Observatory for Infrared Astronomy (SOFIA). Our chords helped constrain the path across Pluto that SOFIA saw. Our ground-based and airborne stellar-occultation effort came only just over two weeks of Earth days and two Pluto days before the flyby of NASA's New Horizons spacecraft.

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Pasachoff, Jay M.0000-0002-4372-4928
Additional Information:© 2017 Elsevier Inc. Received 21 March 2016, Revised 20 April 2017, Accepted 10 May 2017, Available online 3 June 2017. Our observations were supported by NASA Planetary Astronomy grants NNX12AJ29G to Williams College, NNX15AJ82G to Lowell Observatory (now at Gemini Observatory), and NNX10AB27G to MIT, and by the National Research Foundation of South Africa. We are grateful to Alan Gilmore, Pam Kilmartin, Nigel Frost, Robert Lucas, and Carolle Varughese for assistance at Mt. John. Alan Gilmore also supplied the GPS positions of the telescopes. We thank the Mt. John Observatory (Karen Pollard, Director) and the AAVSO for use of its 0.61-m telescope, and Arne Henden for assistance on the night of the occultation. We are grateful to Henry Roe, Lowell Observatory, for lending us the infrared camera. J.M.P. thanks Andrew Ingersoll and the Division of Geosciences and Planetary Astronomy of Caltech for sabbatical hospitality.
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National Research Foundation of South AfricaUNSPECIFIED
Subject Keywords:Occultations; Photometry; Pluto, atmosphere
Record Number:CaltechAUTHORS:20170605-074458161
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Official Citation:Jay M. Pasachoff, Bryce A. Babcock, Rebecca F. Durst, Christina H. Seeger, Stephen E. Levine, Amanda S. Bosh, Michael J. Person, Amanda A. Sickafoose, Carlos A. Zuluaga, Molly R. Kosiarek, Fumio Abe, Masayuki Nagakane, Daisuke Suzuki, Paul J. Tristram, Anicia Arredondo, Pluto occultation on 2015 June 29 UTC with central flash and atmospheric spikes just before the New Horizons flyby, Icarus, Volume 296, 1 November 2017, Pages 305-314, ISSN 0019-1035,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77934
Deposited By: Tony Diaz
Deposited On:05 Jun 2017 21:37
Last Modified:03 Oct 2019 18:03

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