Search Publications
End-of-mission calibration of the Cassini Imaging Science Subsystem
Porco, Carolyn; West, Robert; Verbiscer, Anne +3 more
We provide an end-of-mission update to the in-flight calibration of the Imaging Science Subsystem cameras on the Cassini spacecraft, resolving discrepancies in our previous analyses from 2004 to 2010, incorporating data through the end of the mission, adding a correction for the weak but measurable camera sensitivity decline over time, and providi…
Dust extinction towards the type Ia supernova 2012cu in NGC 4772
Gao, Jian; Jiang, Biwei; Li, Jun +2 more
Using photometric and spectroscopic data of Supernova (SN) 2012cu, a fairly reddened type Ia supernova, we derived its color excess curves and probed the dust extinction in its host galaxy, NGC 4772. In order to derive the extinction as a function of wavelength (i.e., Aλ), we model the color excess curves of SN 2012cu in terms of dust m…
Arecibo radar observations of near-Earth asteroid (3200) Phaethon during the 2017 apparition
Bhiravarasu, Sriram S.; Benner, Lance A. M.; Giorgini, Jon D. +8 more
We report Arecibo S-band (2380 MHz; 12.6 cm) radar observations of near-Earth asteroid (3200) Phaethon during the December 2017 apparition when Phaethon passed within 0.07 au of Earth. Radar images with a resolution of 75 m per pixel reveal a roughly spheroidal shape more than 6 km in diameter at the equator with several discernible surface featur…
Dusk over dawn O2 asymmetry in Europa's near-surface atmosphere
Johnson, Robert E.; Chaufray, Jean-Yves; Oza, Apurva V. +4 more
The evolution of Europa's water-product exosphere over its 85-h day, based on current models, has not been shown to exhibit any diurnal asymmetries. Here we simulate Europa's exosphere using a 3-D Monte Carlo routine including, for the first time, the role of Europa's rotation on the evolution of exospheric molecules tracked throughout the orbit. …
Longitudinal variability in Jupiter's zonal winds derived from multi-wavelength HST observations
Wong, Michael H.; Morales-Juberías, Raúl; Gaulme, Patrick +3 more
Multi-wavelength Hubble Space Telescope (HST) images of Jupiter from the Outer Planets Atmospheres Legacy (OPAL) and Wide Field Coverage for Juno (WFCJ) programs in 2015, 2016, and 2017 are used to derive wind profiles as a function of latitude and longitude. Wind profiles are typically zonally averaged to reduce measurement uncertainties. However…
New constraints on Ganymede's hydrogen corona: Analysis of Lyman-α emissions observed by HST/STIS between 1998 and 2014
Alday, Juan; Saur, Joachim; Roth, Lorenz +4 more
Far-ultraviolet observations of Ganymede's atmospheric emissions were obtained with the Space Telescope Imaging Spectrograph (STIS) onboard of the Hubble Space Telescope (HST) on several occasions between 1998 and 2014. We analyze the Lyman-α emission from four HST campaigns in order to constrain the abundance and variation of atomic hydrogen in G…
Polarimetry observations of comets: Status, questions, future pathways
Hines, Dean C.; Levasseur-Regourd, Anny-Chantal
Polarimetric observations of comets have provided crucial insight into the composition and evolution of cometary dust particles. Herein, we present a brief overview of the polarization properties observed in comets, and some possible interpretations. We also discuss recent imaging polarimetry observations of C/2012 S1 (ISON) and 67P/Churyumov-Gera…
The color ratio-intensity relation in the Jovian aurora: Hubble observations of auroral components
Bonfond, B.; Gérard, J. -C.; Grodent, D. +1 more
Spectral observations made with the long slit of the Space Telescope Imaging Spectrograph (STIS) on board Hubble have been used to construct spectral maps of the FUV Jovian aurora. They reveal that the amount of absorption by overlying methane shows significant spatial variations. In this report, we examine the relationship between the auroral bri…
Analytical model of Europa's O2 exosphere
Mura, Alessandro; Plainaki, Christina; Milillo, Anna +5 more
The origin of the exosphere of Europa is its water ice surface. The existing exosphere models, assuming either a collisionless environment (simple Monte Carlo techniques) or a kinetic approach (Direct Monte Carlo Method) both predict that the major constituent of the exosphere is molecular oxygen. Specifically, O2 is generated at the su…
Probing the interstellar dust in galaxies over >10 Gyr of cosmic history
York, Donald G.; Kulkarni, Varsha P.; Welty, Daniel E. +3 more
Dust has a profound effect on the physics and chemistry of the interstellar gas in galaxies and on the appearance of galaxies. Understanding the cosmic evolution of dust with time is therefore crucial for understanding the evolution of galaxies. Despite the importance of interstellar dust, very little is known about its nature and composition in d…