Near-Infrared Spectroscopy of an Outburst of Comet 29P/Schwassmann-Wachmann 1
ATel #14961; Silvia Protopapa (Southwest Research Institute), Michael S. P. Kelley (Univ. Maryland), Bin Yang (European Southern Observatory/Univ. Diego Portales)
on 8 Oct 2021; 20:40 UT
Credential Certification: Silvia Protopapa (sprotopapa@boulder.swri.edu)
Subjects: Infra-Red, Comet
We report on near-infrared spectroscopy of comet 29P/Schwassmann-Wachmann 1 following a series of outbursts that began on 2021 Sep 25. See the MISSION 29P site for more information on the event. We observed 29P with the NASA IRTF 3.2-m telescope and SpeX instrument, and obtained low-spectral resolution spectroscopy from 0.7 to 2.5 μm using a 0.5"x60" slit. Our data were taken on 2021 Sep 30 at 13:52 UTC and calibrated with a nearby solar analog. The data were acquired under excellent sky conditions. The comet was at a heliocentric distance of 5.9 au and geocentric distance of 5.5 au. The relative reflectance spectrum of 29P shows a 2.0-μm absorption feature with a relative depth of 2.6+/-0.3% with respect to the nearby continuum. We tentatively attribute the nature of this absorption feature to water ice based on its central wavelength, width, and shape. No clear 1.5-μm absorption band of water ice is detected in our spectra, possibly due to signal-to-noise limitations. We estimate an upper-limit for the 1.5-μm band depth of ~1%.