Continuing Fragmentation of C/2019 Y4 (ATLAS)
ATel #13651; Quanzhi Ye (U. Maryland), Man-To Hui (U. Hawaii)
on 21 Apr 2020; 22:46 UT
Distributed as an Instant Email Notice Comets
Credential Certification: Quanzhi Ye (qye@umd.edu)
Referred to by ATel #: 13813
We report the continuing fragmentation of long-period comet C/2019 Y4 (ATLAS), initially reported by ATel #13620, #13622, and #13629, with four major fragments designated A to D in MPEC 2020-H28 using ground-based observations up to UT 2020 April 18. Single-epoch observation with Hubble Space Telescope on UT 2020 April 20.5 (HST/GO-16089, PI Ye) showed only two remaining major fragments, likely A and B in the Minor Planet Center identification, each consists of 1 to 2 brighter components and a couple more fainter components, situated 4 arcsec from each other along their common orbit. Fragments C and D seem to have been reduced into a handful of fainter fragments. At the time of the observation, the comet was at a heliocentric distance of 1.10 au and a geocentric distance of 0.98 au. A preliminary composite image can be found at https://www.astro.umd.edu/~qye/shared/2019Y4_HST_20200420.png.
This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program HST GO 16089.
