Apparent Outburst of Comet 285P/LINEAR
ATel #15544; Michael S. P. Kelley (U. Maryland), Tim Lister (Las Cumbres Observatory), on behalf of the Zwicky Transient Facility Collaboration, and the LCO Outbursting Objects Key Project
on 9 Aug 2022; 16:10 UT
Credential Certification: Tim Lister (tlister@lco.global)
We report on an apparent outburst of comet 285P/LINEAR, previously announced in CBET #5155. Zwicky Transient Facility (ZTF; Bellm et al. 2019, PASP, 131, a8002) data measured in the r-band (5" radius aperture, PS1 photometric system) was 20.02±0.26 mag at 2022 Jul 30.26 UTC. The comet brightened to r=15.94±0.02 mag by the next detection at Aug 03.27 UTC, resulting in an apparent outburst strength of -4.1±0.3 mag in our photometric aperture. However, some ejecta had already moved beyond the 5" radius aperture to at least 9" from the photo-center of the comet. No comet is apparent in an additional r-band ZTF image taken 2022 Jul 31.21 UTC, but the non-detection is the result of the faint comet (preliminary 3-sigma limit ≳19.9 mag) being too close to stellar residual artifacts after reference image subtraction. Thus, the outburst likely started contemporaneously to or after this image was taken. With ATLAS photometry reported to the Minor Planet Center (see CBET #5155), the brightening occurred between Jul 31.21 and Aug 1.35 UTC.
Subsequent observations by ZTF and the Las Cumbres Observatory (LCO) show the comet has continued to brighten since 2022 Aug 3. Photometry within our 5" radius aperture: r=15.47±0.02 and 15.15±0.02 mag at Aug 6.32 and Aug 8.21 UTC, respectively; g=16.50±0.02, 16.02±0.02, 15.64±0.05 mag on Aug 3.32, Aug 6.31, and Aug 7.96 UTC (all observations from ZTF, except for the Aug 7 data from LCO). Monitoring of the comet is encouraged in order to understand the nature of this event and its post-outburst brightening.
Based on observations obtained with the Samuel Oschin Telescope 48-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-2034437 and a collaboration including Caltech, IPAC, Weizmann Institute for Science, Oskar Klein Center at Stockholm University, University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, TANGO Consortium of Taiwan, University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, and IN2P3, France. Operations are conducted by COO, IPAC, and UW.
This work makes use of observations from the Las Cumbres Observatory global telescope network.
