A study of Local Time Variations of Jupiter’s Ultraviolet Aurora using Juno UVS

With 19 successfully completed Perijoves, Juno UVS has collected an enormous amount of data with unprecedented views of the northern and southern auroras spanning all local time geometries. Juno UVS, with its spectral and spatial mapping capabilities allows for the retrieval of both UV brightness as well as color ratio information. Maps of both the brightness and color ratio of the main ovals and polar emissions display strong local time variations, some suggestive of ionospheric local time control while others magnetosphere local time drivers. In this presentation we bring together all the UVS observations to date to show and catalogue the many local time phenomena evident therein

A study of Local Time Variations of Jupiter’s Ultraviolet Aurora using Juno UVS

With 19 successfully completed Perijoves, Juno UVS has collected an enormous amount of data with unprecedented views of the northern and southern auroras spanning all local time geometries. Juno UVS, with its spectral and spatial mapping capabilities allows for the retrieval of both UV brightness as well as color ratio information. Maps of both the brightness and color ratio of the main ovals and polar emissions display strong local time variations, some suggestive of ionospheric local time control while others magnetosphere local time drivers. In this presentation we bring together all the UVS observations to date to show and catalogue the many local time phenomena evident therein

Jupiter's average ultraviolet aurora

Using the best UVS data from each of Junos completed perijoves, we have created average (and variance) maps for the northern and southern auroras of Jupiter. The individual maps for each perijove contain a variety of auroral forms and represent many different levels of activity at a variety of local times. In contrast, the average maps allow features that are nearly always present, but at a lower brightness level, to stand out. The variance maps, on the other hand, tend to highlight auroral structures which occur only rarely. In this presentation we examine what can be learned from these ensemble maps which provide a new look at Jupiter's always surprising auroras

Aurora to Magnetodisk Mapping: Connecting UV Emissions to Events in Jupiter’s Magnetosphere

The Juno Mission carries with it an ultraviolet spectrograph, Juno UVS, meant to map out Jupiter’s auroral emissions from an unprecedented vantage point above Jupiter’s poles. With views of the aurora at all local times, Juno UVS allows for the first comprehensive compilation of the local time variations of the auroral emissions. Using the Vogt et al. (2011, JGR 116, A03220; 2015, JGR 120, 2584-2599) magnetic flux mapping approach we invert the observed auroral emission maps into maps of those emissions in magnetodisk coordinates. In this way, we are able to reconstruct the approximate (depending on the accuracy of the Vogt mapping and JRM09 magnetic field model) structure and evolution of the source regions causing the auroral emissions leading to further insight on the dynamics of the middle to outer magnetosphere. We present mission average disk projected maps, those from assorted perijoves (close flyby of Jupiter by Juno on its highly elliptical orbit of ~53 days), and discuss their temporal evolution over timescales of minutes and hours (a single perijove) to months and years (perijove to perijove)

UVS Observations of Ganymede During Juno Orbits 34 and 35 (invited)

Juno UVS, an ultraviolet spectrograph sensitive to wavelengths 68-210 nm, performed unique observations of Ganymede’s aurora and surface reflectance on the approach to Juno’s 34th and 35th perijoves (PJ). The combination of Juno’s 2 rpm spin rate, UVS’ 7.2° long “dog-bone” shaped slit, and the UVS scan mirror allows for the recording of 7.2° wide scans across Ganymede’s disk every 30 s. Through the wide slits we are able to capture integration times of 17 ms per spin for each resolution element in the observed swath. For the PJ34 Ganymede encounter on June 7, 2021 at 16:56:08 UTC, Juno UVS captured data during 16:52-16:56-17:04 UTC at altitudes varying from 1124-1044-6750 km. Over this time period Ganymede’s angular diameter varied from 89°-91°-33° on the sky, while the nadir solar phase angle varied from 148°-98°-32°. Juno UVS achieves a spatial resolution of ≈0.2° giving a best-case nadir spatial resolution of 4 km. The PJ34 UVS data provide a sparse, but high-resolution look at Ganymede’s aurora, and can be used to locate the last closed field lines to an accuracy of about one degree of latitude. For the PJ35 Ganymede encounter on July 20, 2021 at 16:48:30 UTC, Juno UVS captured data during 16:32-16:48-17:27 UTC. The increased observational period relative to the PJ34 encounter is due to the larger range, 52,610-49,999-67,060 km, making the angular extent of Ganymede only 5.5°-5.7-4.3° on the sky (at a nadir solar phase angle 99°-81°-44°) and the best-case nadir spatial resolution 175 km (comparable to HST imagery). UVS not only spatially resolved Ganymede, but also spectrally separates the prominent 130.4 and 135.6 nm O auroral emissions. We will present maps of the auroral and surface reflected emissions as well as maps of the 130.4/135.6 oxygen emission ratio