Stratospheric balloon observations of comets C/2013 A1 (Siding Spring), C/2014 E2 (Jacques), and Ceres

- First ever images of Oort Cloud comets from a stratospheric balloon observatory.
- Comet Siding Spring produces 6 × 1027 H2O s−1 assuming optically thin 2.7 µm emission, maybe a lower limit.
- Superheat dust population discovered at Comet Jacques.

The Balloon Observation Platform for Planetary Science (BOPPS) was launched from Fort Sumner, New Mexico on September 26, 2014 and observed Oort Cloud comets from a stratospheric balloon observatory, using a 0.8 meter aperture telescope, a pointing system that achieved < 1 arc second pointing stability, and an imaging instrument suite covering the near-ultraviolet to mid-infrared. BOPPS observed two Oort Cloud comets, C/2013 A1 (Siding Spring) and C/2014 E2 (Jacques), at the 2.7 µm wavelength of water emission. BOPPS also observed Ceres at 2.7 µm wavelength to characterize the nature of hydrated materials on Ceres. Absolute flux calibrations were made using observations of A0V stars at nearly the same elevations as each target. The Comet Siding Spring brightness in R-band was magnitude R = 10.8 in a photometric aperture of 17.4″. The inferred H2O production rate from Comet Siding Spring was 6 × 1027 s−1, assuming optically thin emissions, which may be a lower limit if optical depth effects are important. A superheat dust population was discovered at Comet Jacques, producing a bright infrared continuum without evidence for line emission. Observations of Ceres from BOPPS and from IRTF, obtained the same night, did not find evidence for a strong water vapor emission near 2.7 µm and led to an approximate upper limit < 7 × 1027 s−1 for water emission from Ceres.