Atmospheric state of Pluto from the 31 July 2014 stellar occultation
Abstract
On 31 July 2014 (UT), while observing a potential Pluto occultation (m=12, unfortunately obscured by clouds), we imaged a fortuitous occultation by Pluto of a small companion star (m=15) several minutes before the main event (and before the clouds came in) with the 6.5-m Clay telescope at Magellan. The main star’s resulting light curve (essentially flat until the weather intervened) was one of the highest signal-to-noise light curves yet obtained from a Pluto occultation observation. It will be analyzed for possible signatures of dust in the Pluto system (see Levine et al., this meeting). Given the lower signal to noise ratio provided by the secondary star, careful calibration is needed to analyze the atmospheric occultation itself. Several other attempts at observing Pluto occultations in July 2014 were unfortunately clouded out (see Levine et al., Pasachoff et al., this meeting).Using precise astrometry obtained with the 2.5-m DuPont telescope and the 4.3-m Discovery Channel telescope before and after the event, while Pluto and the stars were well-separated, we are able to constrain the closest approach distance of the secondary star occultation event. Using the photometry from these same images, we are also able to characterize the relative brightness of both stars in relation to Pluto (taking care to account for the light from Charon as well). With these two constraints we can analyze the atmospheric signature of the occultation, and provide a current (July 2014) estimate of Pluto’s changing atmospheric diameter. Initial results indicate no large changes in the atmospheric scale height; complete results from the final analysis will be presented with this work.This work was supported in part by NASA Planetary Astronomy grants to MIT (NNX10AB27G) and Williams College (NNX12AJ29G), as well as grants from USRA (#8500-98-003) and Ames Research (#NAS2-97-01) to Lowell Observatory. P.R. acknowledges support from FONDECYT through grant 1120299.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #46
- Pub Date:
- November 2014
- Bibcode:
- 2014DPS....4641909P