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Update on SO2, detection of OCS, CS, CS2, and SO3, and upper limits of H2S and HOCl in the Venus mesosphere using SOIR on board Venus Express
Aoki, S.; Vandaele, A. C.; Trompet, L. +6 more
We report on the update of SO2 and first detections of SO3, CS, and CS2, and detection of OCS above the cloud deck using the SOIR instrument on-board Venus Express, and upper limit profiles of H2S and HOCl. Based on the solar occultation spectra measured by SOIR covering all latitudes over the 2006-2014 …
Ganymede's atmosphere as constrained by HST/STIS observations
Leblanc, F.; Galand, M.; Roth, L. +7 more
A new analysis of aurora observations of Ganymede's atmosphere on the orbital leading and trailing hemispheres has been recently published by Roth et al. (2021), suggesting that water is its main constituent near noon. Here, we present two additional aurora observations of Ganymede's sub-Jovian and anti-Jovian hemispheres, which suggest a modulati…
Evolution of Neptune at near-infrared wavelengths from 1994 through 2022
de Pater, Imke; Wong, Michael H.; Hueso, Ricardo +16 more
Using archival near-infrared observations from the Keck and Lick Observatories and the Hubble Space Telescope, we document the evolution of Neptune's cloud activity from 1994 to 2022. We calculate the fraction of Neptune's disk that contained clouds, as well as the average brightness of both cloud features and cloud-free background over the planet…
Analysis of Charon's spectrum at 2.21- µm from New Horizons/LEISA and Earth-based observations
Singer, Kelsi N.; Stern, S. Alan; Weaver, Harold A. +9 more
We examine the 2.21- µm band from 19 disk-integrated Charon spectra measured by New Horizons/LEISA in the week leading up to its closest encounter with the Pluto system. These observations cover one Charon rotation period. Additionally, we analyze Charon's 2.21- µm band from 22 Earth-based spectra obtained over the last two decades. We…
Uranus ring occultation observations: 1977-2006
Nicholson, Philip D.; French, Richard G.; Sicardy, Bruno +25 more
The Uranian rings were discovered serendipitously on 10 March 1977 during a stellar occultation (Elliot et al., 1977a; Millis et al., 1977), and a rich set of subsequent Earth-based occultations revealed that these narrow and sharp-edged rings were eccentric and inclined, precessing under the gravitational influence of the oblate central planet. C…
Near-IR photometry of the small Uranian satellites with Keck at phase angles 0-2°
de Pater, Imke; Moeckel, Chris; Paradis, Samuel
We present photometric measurements of the seven brightest small inner moons of Uranus (Puck, Belinda, Rosalind, Portia, Juliet, Desdemona and Cressida) obtained with the Keck II telescope at 1.6 and 2 . 2 µm at phase angles of 0.026∘ and 0.36∘ in October-November 2019. We also applied our new calibration technique to the August 2015 data at…
Investigating temporal changes in Jupiter's aerosol structure with rotationally-averaged 2015-2020 HST WFC3 images
Sromovsky, Lawrence A.; Fry, Patrick M.
Annual imaging observations of Jupiter from 2015 onward by the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) as part of the Outer Planet Atmospheres Legacy (OPAL) program (Simon et al., 2015) have provided a valuable data set from which Jupiter's temporal variability can be characterized and modeled. Spectral samples at discrete filter b…
The Bolometric Bond Albedo of Enceladus
West, Robert A.; Nixon, Conor A.; Fry, Patrick M. +13 more
The bolometric Bond albedo is a fundamental parameter of planets and moons. Here, combined observations from the Cassini spacecraft and the Hubble Space Telescope are used to determine the bolometric Bond albedo of Enceladus. We provide the full-disk reflectance of Enceladus across all phase angles (0° -180°) from 150 nm to 5131 nm, a spectral ran…
Drift rates of major Neptunian features between 2018 and 2021
de Pater, Imke; Wong, Michael H.; Hueso, Ricardo +13 more
Using near-infrared observations of Neptune from the Keck and Lick Observatories, and the Hubble Space Telescope in combination with amateur datasets, we calculated the drift rates of prominent infrared-bright cloud features on Neptune between 2018 and 2021. These features had lifespans of ∼ 1 day to ≥1 month and were located at mid-latitudes and …
Keck near-infrared detections of Mab and Perdita
de Pater, Imke; Molter, Edward M.; Moeckel, Chris
We report the first near-infrared detection of Uranus's tiny moon Mab, the presumed source of the blue and diffuse µ ring, using the NIRC2 instrument at Keck Observatory. The detection was permitted by an updated shift-and-stack procedure allowing us to integrate on Mab as it moved across the detector in 23 separate exposures taken over ∼2 h…