Recent Non-active Appearance of Episodically Active Asteroid (6478) Gault
ATel #13885; Josiah Purdum (SDSU), Zhong-Yi Lin (IANCU), Bryce T. Bolin (Caltech/IPAC), Robert Quimby (SDSU), Carey M. Lisse (JHU-APL), Varun Bhalerao (IITB), Dennis Bodewits (Auburn), Chan-Kao Chang (IANCU), Kunal P. Deshmukh (IITB), Chen-Yen Hsu (IANCU), Wing-Huen Ip (IANCU), R. Lynne Jones (UW), Ashish Mahabal (Caltech), Chow-Choong Ngeow (IANCU) on behalf of the Zwicky Transient Facility Collaboration
on 21 Jul 2020; 23:22 UT
Credential Certification: Bryce Bolin (bolin.astro@gmail.com)
Subjects: Optical, Asteroid, Comet
We report the non-active appearance of (6478) Gault on 2020 June 23 UTC and 24 UTC. These observations, taken as (6478) Gault was exiting from Solar conjunction, are in stark contrast to several epochs of activity observed in early to mid-2019 (Ye et al. 2019 ApJL, 874, L16; Jewitt et al. 2019 ApJL, 876, L19). Detections of (6478) Gault in deep stack images obtained with the Lulin One-meter Telescope (LOT; 2100 s in R band; angular resolution 0.385 arcsec/pixel) and Mount Laguna Observatory 1.0-meter telescope (MLO-1.0m; 3600 s in R band; 0.716 arcsec/pixel) have an angular FWHM of ~2" similar to nearby background stars. We measured a 3-sigma lower limit on the surface brightness of R~25.8 mag/sq.arcsec within a 3.5"-5" annulus centered on the asteroid in the MLO-1.0m 2020 June 24 UTC data. For comparison, the 3.5"-5" annulus surface brightness centered on the detection of (6478) Gault in images taken by the Astrophysical Research Consortium 3.5-meter telescope on 2019 February 9 UTC when the asteroid had an extended appearance with multiple tails was R~24 +/- 0.1 mag/sq.arcsec. We recommend follow-up and subsequent monitoring of this object by other facilities.
Our work includes observations obtained with the Apache Point Observatory 3.5-meter telescope, which is owned and operated by the Astrophysical Research Consortium. We thank the Director (Nancy Chanover) and Deputy Director (Ben Williams) of the Astrophysical Research Consortium (ARC) 3.5-meter telescope at Apache Point Observatory for their enthusiastic and timely support of our observations. We also thank Russet McMillan, Ted Rudyk, Candace Gray, Jack Dembicky, and the rest of the APO technical staff for their assistance in our observations.
Image of (6478) Gault from MLO-1.0m in R band taken on 2020 June 24 UTC and from the ARC 3.5-m in r band taken on 2019 February 9 UTC
