Outburst of comet P/2008 Y1 (Boattini)

ATel #13175; Outburst of comet P/2008 Y1 (Boattini)
on 8 Oct 2019; 20:13 UT
Credential Certification: Michael Kelley (msk@astro.umd.edu)

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We report the discovery of an apparent outburst of comet P/2008 Y1 (Boattini), recently recovered by G. Borisov on 2019 Sep 2 UTC with the temporary designation P/2019 R1 (CBET #4663). We searched the Zwicky Transient Facility (Bellm et al. 2019, PASP, 131, a8002) survey archive for images of the comet based on the revised orbit. It was observed and detected on 14 nights between 2019 Jul 15 to 2019 Oct 05 UTC. Photometry up to 2019 Sep 22 measured with a 5" radius aperture is tabulated below, calibrated to the PS1 catalog (Tonry et al. 2012, ApJ, 750, 99). We estimate a coma color of g-r=0.60±0.02 mag. The photometry approximately follows the trend: r=16.06 + 5 log10(Delta) + 15 log10(rh) + Phi(phase) (RMS 0.09 mag), where Delta is the observer-comet distance, rh is the heliocentric distance, and Phi(phase) is the Halley-Marcus phase function (Schleicher & Bair 2011, AJ 141, 177) at the given phase angle, expressed in magnitudes. Between 2019 Aug 21.51 and 24.50 UTC, 9 to 12 days before recovery, the comet brightened from g=18.03±0.07 to 17.39±0.05 mag, then slowly returned to its nominal brightness by 2019 Sep 10.49 UTC. The event appears to be a cometary outburst, with a strength of at least -0.62±0.05 mag.

 
      Date      rh   Delta Phase Filter  m     unc    r   Trend Residuals 
     (UTC)     (au)   (au) (deg)        (mag) (mag) (mag) (mag)   (mag)   
------------- ------ ----- ----- ------ ----- ----- ----- ----- --------- 
2019-07-15.49 -1.439 1.704  36.5      r 18.49  0.09 18.49 18.53     -0.04 
2019-07-30.47 -1.359 1.595  39.2      g 18.48  0.06 17.88 17.98     -0.10 
2019-07-30.49 -1.359 1.595  39.2      r 17.93  0.05 17.93 17.98     -0.05 
2019-08-21.51 -1.284 1.497  41.8      g 18.03  0.07 17.43 17.45     -0.02 
2019-08-24.50 -1.279 1.489  42.0      g 17.39  0.05 16.79 17.41     -0.62 
2019-08-28.49 -1.273 1.480  42.2      g 17.41  0.03 16.81 17.36     -0.55 
2019-08-28.51 -1.273 1.480  42.2      r 16.81  0.02 16.81 17.36     -0.55 
2019-08-31.48 -1.270 1.474  42.4      g 17.69  0.03 17.09 17.34     -0.25 
2019-08-31.51 -1.270 1.474  42.4      r 17.10  0.02 17.10 17.34     -0.24 
2019-09-07.49  1.268 1.465  42.5      g 17.85  0.04 17.25 17.31     -0.06 
2019-09-07.52  1.268 1.465  42.5      r 17.21  0.03 17.21 17.31     -0.10 
2019-09-10.49  1.269 1.462  42.6      g 17.91  0.04 17.31 17.31     -0.00 
2019-09-10.51  1.269 1.462  42.6      r 17.30  0.03 17.30 17.31     -0.01 
2019-09-13.47  1.271 1.460  42.5      r 17.30  0.05 17.30 17.32     -0.02 
2019-09-14.52  1.273 1.459  42.5      r 17.38  0.05 17.38 17.33      0.05 
2019-09-22.49  1.286 1.457  42.4      r 17.42  0.06 17.42 17.39      0.03 
2019-09-22.52  1.286 1.457  42.4      g 18.17  0.07 17.57 17.39      0.18 

Columns - rh, heliocentric distance (negative for pre-perihelion); Delta, observer-comet distance; Phase, Sun-comet-observer angle; Filter, ZTF bandpass name; m, apparent magnitude through filter in 5" radius aperture; unc, uncertainty on m; r, effective r-band lightcurve after transforming g- into r-band photometry; Trend, the best-fit trend; and Residuals, the residuals from the fit.

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.