tokens: gyros that have failed to date. During the decline of G2 performance, and as stability issues with G3 were encountered, the number of consecutive HST orbits without a bias update evolved from eight orbits to four in 2017 June, and finally to two orbits in early 2018, affecting multi-orbit coverage of PJs 12 and 19, as well as OPAL 2018 and 2019 observations of Jupiter. 2.7. Photometric Calibration The latest photometric calibration for WFC3/UVIS (Deustua et al. 2016 , 2017 ), called “UVIS 2.0,” includes new flat fields and normalization procedures (Mack et al. 2016 ) compared to the earlier “UVIS 1.0” calibration pipeline in use prior to 2016. The WFC3 quad filters (i.e., FQ889N for the Jupiter observations discussed here) have not been updated, so we have included an estimated 3% reduction in calibrated fluxes in quad filters, based on average changes in photometric calibrations for other filters between the UVIS 1.0 and 2.0 calibration systems. Photometric uncertainties in the UVIS 2.0 calibration are estimated to be 1.2%–1.3% (Deustua et al. 2016 , 2017 ). Calibrated HST data are images with data numbers corresponding to count rates in units of e − s −1 , and the FITS header keyword PHOTFLAM gives the inverse sensitivity factor to convert to spectral irrandiance units of erg cm −2 s −1 Å −1 . But for solar system science in the NUV–NIR range, reflectance in I / F units is commonly used. To convert the image data units of e − s −1 to I / F , we provide a FITS header keyword PHOTIF and its uncertainty, SIG_PHOT, such thatwhere Ω is the solid angle of a WFC3/UVIS pixel with default astrodrizzle parameters (0.03962 2 arcsec 2 ), and πF ⊙ is the solar spectral irradiance at Jupiter’s orbital distance at the time of the exposure within the bandpass of the spectral element. To calculate πF ⊙ , we use the Colina et al. ( 1996 ) solar spectrum, the heliocentric distance from the JPL Horizons ephemeris system, 13 13 JPL Horizons URL is https://ssd.jpl.nasa.gov/?horizons . and spectral element throughput curves available directly for download from STScI. 14 14 WFC3/UVIS throughputs are at http://stsci.edu/WFC3/UVIS/SystemThroughput or http://stsci.edu/hst/instrumentation/wfc3/performance/throughputs . The SIG_PHOT uncertainty in our I / F calibration is dominated by a systematic 5% uncertainty in the solar spectrum (Colina et al. 1996 ), but also includes a 1% error typical of photometric zero-point uncertainty (Deustua et al. 2017 ). 2.8. Temporal Coverage Although most HST observations had timing linked to Juno perijoves, there are two exceptions. Observations in the Outer Planet Atmospheres Legacy (OPAL) program were taken near solar opposition, to maximize spatial resolution at Jupiter (Simon et al. 2015 ). OPAL 2017 observations happened very close to perijove 5. A cluster of imaging observations in 2017 January were planned to coincide with a Juno perijove, under the original plan with 14 day Juno science orbits. When Juno was instead kept on
ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O B-CelestialObject O O O B-Survey I-Survey I-Survey I-Survey O O B-CelestialObject O O O O O O O O B-Instrument B-Citation I-Citation I-Citation I-Citation O B-Citation O O B-Software I-Software O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O B-Software I-Software I-Software I-Software O O O O O O B-Instrument O O O B-Wavelength O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Software I-Software O B-Software I-Software I-Software O O O O B-Software I-Software O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation O O B-Telescope O O O O O O O O O O O O O O O O O O O O B-Software O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Instrument O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Software O O O O O O O O O O O O O O O O B-Instrument O O O B-Software O O O O O O O O O O O O O O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation B-CelestialObject O O O O O O B-Software I-Software I-Software I-Software O O B-Software I-Software O O B-URL O O O O O O O O O O O B-Organization O O B-Instrument O O O B-URL O B-Formula O O O O O O O O O O O O O O O O O O O B-CelestialObject O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O B-Telescope O O O O O B-Mission O O O O O O O O B-Survey I-Survey I-Survey I-Survey B-Survey O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O B-CelestialObject B-Citation I-Citation I-Citation I-Citation O B-Survey I-Survey O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Mission O O O B-Mission O O O O