C/2015 ER61 (PANSTARRS)

DEPARTED

Type: Periodic Perihelion date: 9 May 2017 Perihelion distance (q): 1.0 Aphelion distance (Q) : 764 Period (years): 7,494 Eccentricity (e): 1.00 Inclination (i): 6.3 JPL orbit diagram COBS lightcurve PanSTARRS 1 discovered a 21st magnitude asteroid in images taken with the 1.8m Ritchey-Chretien on 14 March 2015. The asteroid was originally classified as an Amor type NEO, but was reclassified in a near parabolic orbit. The orbit has a Tisserand criterion with respect to Jupiter of 1.27, a Jupiter MOID of 0.029 au and an earth MOID of 0.10 au. Observations in December 2015 and January 2016 showed that the object had cometary features and a coma was then noted in images from June 2015. It was re- designated as a comet on MPEC 2016-C01 [1 February 2016]. Juan Gonzalez recovered the comet after solar conjunction on 6 December at magnitude 10.4. The comet brightened fairly slowly, but underwent a short-lived outburst in early April when it reached 6th magnitude. It faded more rapidly after perihelion than it had brightened before and clearly this was an effect of the outburst. A secondary component was detected by Belgian amateur Erik Bryssinck on 13 June 2017. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 04-Feb-16 17.91 0.02 17.7 0.2 07-Feb-16 17.86 0.03 17.5 0.2 05-Mar-16 17.15 0.03 15.7 0.2 29-Mar-16 16.90 0.02 16.7 0.2 12-Apr-16 16.75 0.01 16.5 0.2 01-May-16 16.82 0.02 16.0 0.2 11-May-16 16.77 0.01 16.3 0.2 30-May-16 16.65 0.01 14.8 0.2 09-Jan-17 14.48 0.04 11.6 0.9 27-Jan-17 14.11 0.02 11.7 0.9 01-Feb-17 13.88 0.05 10.7 1.2 06-Feb-17 14.03 0.03 11.0 1.1 23-Feb-17 13.64 0.05 11.4 0.6 07-Mar-17 13.22 0.03 10.1 0.7 16-Mar-17 12.94 0.03 9.7 1.8 20-Mar-17 12.80 0.03 9.6 1.7 29-Mar-17 12.49 0.02 9.2 3.3 02-Apr-17 12.46 0.04 8.8 3.5 10-Apr-17 11.05 0.01 7.3 6.3 14-Apr-17 11.27 0.01 7.5 6.4 18-Apr-17 11.14 0.05 7.2 5.1 23-Apr-17 11.54 0.03 8.0 5.8 03-May-17 11.88 0.03 7.9 5.5 07-May-17 11.82 0.02 7.3 4.9 13-May-17 11.87 0.09 7.7 3.1 26-May-17 12.27 0.03 9.1 2.4 13-Jun-17 12.90 0.04 10.4 3.7 26-Jun-17 13.53 0.01 9.6 3.1 03-Jul-17 13.70 0.01 10.4 2.8 13-Jul-17 14.10 0.02 10.9 2.0 20-Jul-17 14.12 0.04 10.9 2.9 24-Jul-17 14.06 0.04 10.9 3.0 30-Jul-17 14.64 0.02 11.2 1.8 04-Aug-17 14.68 0.02 11.5 1.4 17-Aug-17 14.88 0.03 11.8 1.3 19-Aug-17 14.90 0.04 11.8 1.4 29-Aug-17 15.17 0.06 11.8 1.5 14-Sep-17 15.45 0.01 12.9 0.8 22-Sep-17 15.45 0.01 12.8 1.0 01-Oct-17 15.57 0.03 12.6 0.9 12-Oct-17 15.45 0.03 12.2 0.8 17-Oct-17 15.60 0.01 13.5 0.8 21-Oct-17 15.51 0.04 12.5 0.9 30-Oct-17 15.57 0.01 13.4 0.9 14-Nov-17 15.67 0.02 13.4 0.8 28-Nov-17 16.06 0.01 13.1 0.6 14-Dec-17 16.59 0.03 14.1 0.9 02-Jan-18 17.09 0.03 14.3 0.6 14-Jan-18 17.40 0.06 15.4 0.5 21-Jan-18 17.57 0.02 16.1 0.5 02-Feb-18 17.95 0.05 16.5 0.4