Disintegration of Comet C/2019 J2 (Palomar)
ATel #12931; Quanzhi Ye (Caltech/IPAC), Michael S. P. Kelley (U. Maryland), D. Bodewits (Auburn U.) on behalf of the Zwicky Transient Facility Collaboration, Jean-Francois Soulier (Maisoncelles), Krisztian Sarneczky (Konkoly Observatory), Francois Kugel (Observatoire de Chante-Perdrix, Dauban)
on 12 Jul 2019; 17:16 UT
Distributed as an Instant Email Notice Comets
Credential Certification: Quanzhi Ye (qye@caltech.edu)
We report the apparent disintegration of comet C/2019 J2 (Palomar), first detected by Soulier and Sárneczky on images taken on UT 2019 July 6-7. Soulier reported that the comet was 1.8 magnitude fainter than predicted in images taken on UT 2019 July 6.90 by a 0.30-m telescope at Maisoncelles, and a “très diffus” (very diffuse) appearance (https://fr.groups.yahoo.com/neo/groups/les_cometes/conversations/messages/8599, in French). Sárneczky reported the activity of the comet “has been dropped” based on images taken on UT 2019 Jun. 30.89, July 6.95 and 7.97 by a 0.60-m Schmidt telescope at Konkoly Observatory, Piszkéstető, Hungary (https://www.facebook.com/groups/watchcomet/permalink/905404519630011/). The comet started to become noticeably diffuse on the images taken on July 6.
After receiving the reports from Soulier and Sárneczky, Ye examined the images taken with the Zwicky Transient Facility (ZTF) operated on the 1.2-m Oschin Schmidt telescope at Palomar Observatory (Bellm et al. 2019, PASP, 131, a8002), and derived the following photometry using circular apertures with a projected radius of 10,000 km and calibrated to the Pan-STARRS photometry system, dating back to June 16. The comet was 1.78 to 1.73 au from the Sun and 1.94 to 1.76 au from the Earth between June 16 and July 9, respectively. The discovery data on 2019 Apr. 27 and May 9 (c.f. MPEC 2019-J123), with photometry remeasured using the apertures defined above, are also listed for reference.
Date UT mag dmag band
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2019 Apr. 27.49 17.93 0.07 r
2019 May 9.47 17.45 0.04 r
2019 Jun. 16.34 17.44 0.05 r
2019 Jun. 16.45 17.79 0.05 g
2019 Jun. 23.43 17.53 0.05 r
2019 Jun. 27.34 17.91 0.05 r
2019 Jun. 27.47 18.20 0.06 g
2019 Jul. 2.35 17.89 0.05 r
2019 Jul. 9.32 18.71 0.08 g
The ZTF image on July 9 shows that the comet has lost its central condensation. Although the disintegration only becomes apparent at some time between the ZTF observation on July 2 and the Maisoncelles/Konkoly observation on July 6, ZTF photometry suggests that the process likely started much earlier, possibly in early May. The brightness of the comet increased by ~0.6 mag from Apr. 27 to May 9, then decreased by an equal amount from May 9 to Jul. 2, while a typical comet would have brightened by 1.0 mag from Apr. 27 to Jul. 2, assuming m ~ 5 log10(Delta) + 10 log10(r_h) (where r_h is the heliocentric distance and Delta is the geocentric distance) and a phase coefficient of 0.04 mag/deg.
The disintegration is further confirmed by Kugel, who reported a “bien diffuse et un peu allongée” (diffuse and somehow elongated) coma measured 30” in size towards P.A. 80 deg (https://fr.groups.yahoo.com/neo/groups/les_cometes/conversations/messages/8601, in French).
Part of this work makes use of observations obtained with the Samuel Oschin Telescope 48-inch at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. We thank Charles Bell for bringing Soulier’s initial report to our attention.
