A. R. Gomes-Junior

TL;DR: In this paper, a central flash observed on 2015 June 29 is consistent with New Horizons REX profiles, provided that large diurnal temperature variations (not expected by current models) occur over Sputnik Planitia; and/or hazes with tangential optical depth of ~0.3 are present at 4-7 km altitude levels.

Abstract: The prediction of stellar occultations by Transneptunian objects and Centaurs is a difficult challenge that requires accuracy both in the occulted star position as for the object ephemeris. Until now, the most used method of prediction involving tens of TNOs/Centaurs was to consider a constant offset for the right ascension and for the declination with respect to a reference ephemeris. This offset is determined as the difference between the most recent observations of the TNO and the reference ephemeris. This method can be successfully applied when the offset remains constant with time. This paper presents an alternative method of prediction based on a new accurate orbit determination procedure, which uses all the available positions of the TNO from the Minor Planet Center database plus sets of new astrometric positions from unpublished observations. The orbit determination is performed through a numerical integration procedure (NIMA), in which we develop a specific weighting scheme. The NIMA method was applied for 51 selected TNOs/Centaurs. For this purpose, we have performed about 2900 new observations during 2007-2014. Using NIMA, we succeed in predicting the stellar occultations of 10 TNOs and 3 Centaurs between 2013 and 2015. By comparing the NIMA and JPL ephemerides, we highlighted the variation of the offset between them with time. Giving examples, we show that the constant offset method could not accurately predict 6 out of the 13 observed positive occultations successfully predicted by NIMA. The results indicate that NIMA is capable of efficiently refine the orbits of these bodies. Finally, we show that the astrometric positions given by positive occultations can help to further refine the orbit of the TNO and consequently the future predictions. We also provide the unpublished observations of the 51 selected TNOs and their ephemeris in a usable format by the SPICE library.

TL;DR: In this paper, the authors analyzed two multi-chord stellar occultations by Pluto observed on July 18th, 2012 and May 4th, 2013, and monitored respectively from five and six sites.

TL;DR: In this article, the authors derived results derived from four stellar occultations by the plutino object (208996) 2003~AZ$_{84}, detected at January 8, 2011, February 3, 2012, December 2, 2013, and November 15, 2014 (multi-chord).

TL;DR: In this article, the authors used eleven stellar occultations by Pluto observed between 2002 and 2016 to retrieve atmospheric profiles (density, pressure, temperature) between $5 km and $380 km altitude levels (i.e. pressures from about 10 microbar to 10 nanobar).