First results of JWST GO-1 program #1658: Pluto's climate system with JWST

We will present the first results on an accepted JWST GO-1 program (#1658) dedicated to the study of Pluto's climate system. The program combines (i) NIRCam filter imaging (3 visits, 4 SW filters - F070W, F410M, F090W, F115W, F140M) to map the albedo and methane ice distribution with resolution comparable to HST visible imaging (ii) MIRI imaging (6 visits, 4 filters - F1550W, F1800W, F2100W, F2550W) to separately constrain Pluto's and Charon's surface thermal and energetical properties, and to assess the possible effect of haze in Pluto's energy budget (iii) a deep MIRI/MRS spectrum, to obtain new insights on Pluto's atmosphere composition, including yet undetected species, and to explore the 5-15 μm reflected spectrum of of Pluto (and Charon), searching for hydrocarbon ices and irradiation products. (iv) a MIRI/LRS spectrum of Charon (and Pluto) to search for non-H2O ice signatures. NIRCam and MIRI imaging data were acquired over Oct. 5-11, 2022. The deep MIRI/MRS spectrum (~10000 sec. on source) was observed on May 4, 2023. Following a failed execution in Oct. 2022, MIRI/LRS data will be reobserved in Sept.-Oct. 2023. Highlights of the MIRI observations include (i) the measurement of separate thermal lightcurves for Pluto and Charon at 15, 18, 21 and 25.5 μm (ii) the detection of emission from several hydrocarbons from Pluto's atmosphere over 12-16 μm and of fluorescent emission of CH4 and CH3D at 7.7 and 8.6 μm respectively (iii) the detection of new solid-state spectral features over 6-11 μm. Data and first analyses will be presented at the meeting.