C/2016 R2 (PANSTARRS)

DEPARTED

Type: Periodic Perihelion date: 9 May 2018 Perihelion distance (q): 2.6 Aphelion distance (Q) : 1,408 Period (years): 18,733 Eccentricity (e): 1.00 Inclination (i): 58.2 JPL orbit diagram COBS lightcurve A 19th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 30 August 2016. Early electronic magnitudes put the comet at 13th magnitude in late December 2016 and brightening quite rapidly. This rate of brightening did not persist and it scarcely brightened over the next eight months. The observations are not a good fit to a steady curve, and it seems likely that the comet has periods of greater activity. It was a couple of magnitudes brighter than the mean curve in September 2018 and continuted brightening into November even though its distance from the Sun was increasing. It re-appeared on the PCCP in May/June 2019 as COR8032. Professional observations in December 2017 suggest that the comet is very rich in CO, and relatively poor in HCN. It may be quite a large object as it was producing about a third the amount of CO compared to 1995 O1 (Hale-Bopp) at the same distance. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 07-Oct-16 17.15 0.10 14.1 0.2 28-Oct-16 17.15 0.02 14.5 0.2 24-Nov-16 16.49 0.03 13.4 0.4 18-Dec-16 16.52 0.04 13.4 0.5 26-Dec-16 16.53 0.17 13.1 0.3 22-Jan-17 16.54 0.02 13.6 0.5 16-Feb-17 16.64 0.06 13.8 0.5 07-Aug-17 16.05 0.04 13.7 0.6 18-Oct-17 15.11 0.00 12.0 1.1 12-Nov-17 14.99 0.01 11.5 1.5 21-Nov-17 14.65 0.01 11.5 1.8 11-Dec-17 14.42 0.01 11.3 5.2 22-Dec-17 14.24 0.09 11.1 7.1 11-Jan-18 14.56 0.01 11.4 4.0 19-Jan-18 14.25 0.07 11.1 5.8 07-Feb-18 14.38 0.09 11.2 3.3 14-Feb-18 14.75 0.07 11.6 2.8 08-Mar-18 14.90 0.01 11.5 2.6 13-Mar-18 14.90 0.02 11.8 3.2 02-Apr-18 14.93 0.02 11.8 2.3 09-Apr-18 14.75 0.03 11.6 1.8 04-Dec-18 16.01 0.03 12.8 1.1 14-Dec-18 16.08 0.05 13.2 1.0 21-Dec-18 16.21 0.04 14.1 0.7 02-Jan-19 16.28 0.01 13.7 1.0 09-Jan-19 16.25 0.01 13.9 1.1 08-May-19 16.63 0.02 13.8 1.0 24-May-19 16.76 0.04 14.0 0.9 01-Jun-19 16.62 0.07 13.6 1.0 08-Jun-19 16.93 0.03 14.1 0.9 22-Jun-19 17.09 0.03 14.6 1.0 29-Jun-19 17.32 0.06 14.7 0.7 20-Mar-20 19.34 0.07 17.5 0.2 29-Mar-20 19.50 0.05 18.1 0.2