In-flight Characterization and Calibration of the Juno-ultraviolet Spectrograph (Juno-UVS)

Journal Article · Fri Feb 01 04:00:00 EST 2019 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/AAFB36· OSTI ID:22897279

Hue, Vincent; Randall Gladstone, G.; Greathouse, Thomas K.; Kammer, Joshua A.; Davis, Michael W.; Versteeg, Maarten H.; Bolton, Scott J.; Byron, Ben D. ^[1]; Bonfond, Bertrand; Grodent, Denis C.; Gérard, Jean-Claude ^[2]

---

1. Southwest Research Institute, San Antonio, Texas (United States)
2. STAR Institute, LPAP, Université de Liège, Liège (Belgium)

Juno is the first polar orbiter around Jupiter. Juno possesses a suite of instruments designed to measure the electron and ion populations in the Jupiter magnetosphere, leading to the powerful Jovian aurorae. The Ultraviolet Spectrograph onboard Juno (Juno-UVS) is a photon-counting imaging spectrograph (68–210 nm), designed to observe and characterize Jupiter’s far-ultraviolet aurorae. The instrument borrows heavily from previous Alice and UVS instruments led by Southwest Research Institute (New Horizons and Rosetta Alices, LRO-LAMP), with several major improvements. The pointing flexibility offered by the UVS scan mirror combined with Juno’s spin allows UVS access to half of the sky at any given moment. This paper describes how we leverage this extensive database to track the evolution of Juno-UVS calibration with time throughout the mission. UVS observes 7.2° × 360°-long swaths of the sky for each rotation of the spacecraft (nominally 2 rpm). This paper describes how the very substantial amount of stellar spectra has been used to monitor the health of the instrument over the mission. As of PJ14 (2018 July 16), more than 8700 spectra of O, A, and B stars have been extracted in the V-magnitude range of ∼0–7, and more than 99% of the sky was mapped. Selected stars among this list were used to calibrate the UVS bandpass, using observations from the International Ultraviolet Explorer and the Hubble Space Telescope. The retrieved effective area of the instrument is 0.30 ± 0.03 cm{sup 2} at 125 nm, 0.15 ± 0.02 cm{sup 2} at 140 nm, and 0.05 ± 0.01 cm{sup 2} at 160 nm.

• OSTI ID: 22897279
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 2 Vol. 157; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALICE
AURORAE
CALIBRATION
DATA ANALYSIS
ELECTRONS
FAR ULTRAVIOLET RADIATION
JUPITER PLANET
PARTICLE TRACKS
PHOTON COUNTING
ROTATION
SPACE
SPACE VEHICLES
SPECTRA
SPECTROSCOPY
STARS
TELESCOPES