Enabling a First in a Lifetime Multi-Wavelength Gas and Dust Coma Characterization of the Centaur 39P/Oterma

Centaurs are the dynamical intermediary between the more distant and thermally pristine Trans-Neptunian Objects (TNOs) with the more processed and active Jupiter-Family Comets (JFCs). In the Centaur region between Neptune and Jupiter the thermal activation of many cosmogonically abundant volatile species occurs driving comae activity. Investigations of these distant comae provide salient data to test models of the solar system's formation. To date thorough Centaur gas comae characterizations are prohibitive due to instrumental sensitivity limitations, however the newly launched James Webb Space Telescope (JWST) will provide the sensitivities necessary to probe Centaur gas comae. Six Centaurs have been approved for JWST Cycle 1 gas comae characterizations [McKay et al. 2021] with additional contemporaneously acquired dust comae observations from other observatories. Of the six JWST Centaur targets 39P/Oterma is predicted to be beyond suitable characterization through ground-based assets during the Cycle 1 NIRSpec observations. We request 2 HST orbits during Cycle 29 (Jul. - Aug. 2022) of WFC3-UVIS imaging to contemporaneously characterize the dust coma of the Centaur 39P/Oterma during scheduled Cycle 1 JWST NIRSpec gas coma characterization. The tight, stable, and well characterized WFC3 PSF in combination with HST's sensitivity to low surface brightness provide the only observational platform currently available to detect and isolate the flux from 39P's dust coma from its nucleus contribution. If a suitable ramp up of comae activity occurs before the scheduled JWST observations we will forgo the HST observations, instead utilizing ground-based assets.