Rotation of Comet C/2020 F3 (NEOWISE)
ATel #13945; Michal Drahus (Jagiellonian University in Krakow), Piotr Guzik (Jagiellonian University in Krakow), Andrew Stephens (Gemini Observatory), Steve B. Howell (NASA Ames Research Center), Stanislaw Zola (Jagiellonian University in Krakow), Mikolaj Sabat (Jagiellonian University in Krakow), Daniel E. Reichart (University of North Carolina at Chapel Hill)
on 14 Aug 2020; 17:19 UT
Distributed as an Instant Email Notice Comets
Credential Certification: Michal Drahus (drahus@oa.uj.edu.pl)
We report initial observations of the gas coma of comet C/2020 F3 (NEOWISE) made using the Gemini North telescope (Mauna Kea) as part of Director's Discretionary Time program GN-2020A-DD-115. Images obtained between UT 2020 July 28.2 and August 10.2 with the Gemini Multi-Object Spectrograph (GMOS-N) in the SDSS g' band and the narrow 468/8 nm band, and enhanced by the division by azimuthal median (e.g. Samarasinha & Larson 2014, Icarus 239, 168), show rapidly expanding recurrent spiral features in the C_2 coma produced by nucleus rotation. The observed morphological evolution implies a rotation period of 7.58 +/- 0.03 hr with no obvious temporal changes or deviations from a simple rotation state over the reported time interval. This result is consistent with an earlier value of 7.5 +/- 2.3 hr reported by Masi 2020 (CBET 4816). The Gemini North imaging program of comet C/2020 F3 (NEOWISE) has been supported by multicolor (Johnson-Cousins) observations using small telescopes operating as part of the Skynet network.
Based on observations obtained at the international Gemini Observatory, a program of NSF's NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigacion y Desarrollo (Chile), Ministerio de Ciencia, Tecnologia e Innovacion (Argentina), Ministerio da Ciencia, Tecnologia, Inovacoes e Comunicacoes (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). We thank J. Blakeslee for rapid evaluation and approval of our Gemini North director's discretionary time request and the observatory staff for assistance. M.D. and P.G. are grateful for support from the National Science Centre of Poland through SONATA BIS grant 2016/22/E/ST9/00109.
