Target of Opportunity Imaging of an Unusual Cloud Feature on Uranus
Abstract
The planet Uranus demonstrated increased atmospheric activity around the time of the 2007 equinox, likely in response to extreme insolation change {Sromovsky et al. 2009, Icarus 203, 265}. Convective sites in the planet's southern hemisphere reached unprecedented altitudes in 2003 {Hammel et al. 2005, Icarus 175, 284}; a bright northern feature showed the highest contrast yet detected in an outer planet atmosphere {Sromovsky et al. 2007, Icarus 192, 558}; and a dark atmospheric feature was detected by Hubble {Hammel et al. 2009, Icarus 201, 257}. The historical record makes references to discrete structures {both bright and dark} on Uranus during previous equinoctial apparitions {the last equinox occurred in 1965}. The best amateur facilities are now just able to resolve the disk of Uranus and detect such activity if it is very large or has very high contrast. Amateurs also have access to a great many nights of telescope time. If a discrete cloud feature on Uranus is reported through the amateur network, we propose to obtain follow-up images with Hubble's WFC3. The proposed TOO images will permit determination of detailed structure of the feature at visible wavelengths, and will provide vertical and horizontal constraints on the feature's scattering properties. Hubble is the only facility that can provide such information at visible wavelengths. The proposal was accepted in earlier cycles, but not executed because the defined criteria for activation were not met. Because the timescales of change on Uranus are unknown, we resubmit this for consideration in the current cycle.
- Publication:
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HST Proposal
- Pub Date:
- October 2011
- Bibcode:
- 2011hst..prop12463H