C/2015 V2 (Johnson)

DEPARTED

Type: Hyperbolic Perihelion date: 12 June 2017 Perihelion distance (q): 1.6 Aphelion distance (Q) : n/a Period (years): n/a Eccentricity (e): 1.00 Inclination (i): 49.9 JPL orbit diagram COBS lightcurve Jess A Johnson discovered a 17th magnitude comet in Catalina Sky Survey images with the 0.68m Schmidt on 3 November 2015. The MPC preliminary elements suggested that the comet would reach perihelion at 0.9 au in February 2017. JPL gave a 1-sigma uncertainty in the time of perihelion of 206 days and in perihelion distance of 0.6 au, so the elements were likely to change substantially. A new MPEC was issued the next day (V62) and this gave perihelion at 1.6 au in June 2017. The JPL elements were similar with the 1-sigma uncertainty now 5 days and an earth MOID of 0.7 au. The latest JPL figures give an earth MOID of 0.6 au and classify the comet as a hyperbolic one. JJ Gonzalez picked up the comet at 12th magnitude in early September 2016, much earlier than expected though consistent with extrapolation of electronic observations by Kevin Hills. In the end the comet brightened quite slowly, but became a good binocular object in the spring and early summer. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 06-Nov-15 16.86 0.01 16.4 0.2 17-Nov-15 16.83 0.02 15.5 0.2 04-Dec-15 16.71 0.02 16.3 0.2 11-Dec-15 16.75 0.04 16.0 0.2 17-Dec-15 16.77 0.01 16.3 0.2 03-Feb-16 16.11 0.01 15.6 0.2 10-Feb-16 16.20 0.02 15.5 0.3 25-Feb-16 16.06 0.03 15.5 0.3 04-Mar-16 16.07 0.01 14.7 0.2 14-Mar-16 15.70 0.00 15.2 0.2 24-Mar-16 15.44 0.06 14.3 0.2 19-Apr-16 15.47 0.01 14.7 0.2 09-Jan-17 13.62 0.02 11.0 1.1 21-Jan-17 13.58 0.01 11.0 1.0 25-Jan-17 13.65 0.01 11.3 1.2 29-Jan-17 13.60 0.01 11.2 1.5 02-Feb-17 13.53 0.01 11.1 1.5 06-Feb-17 13.51 0.02 10.8 1.6 18-Feb-17 13.06 0.05 10.0 1.9 22-Feb-17 13.22 0.02 10.2 1.1 28-Feb-17 12.87 0.03 9.7 3.8 07-Mar-17 13.06 0.03 9.8 2.6 18-Mar-17 12.77 0.03 9.6 3.6 23-Mar-17 12.85 0.03 9.7 3.9 27-Mar-17 12.88 0.01 9.6 4.3 31-Mar-17 12.69 0.04 9.0 5.2 03-Apr-17 12.38 0.07 9.2 4.0 12-Apr-17 12.70 0.01 9.4 4.9 18-Apr-17 12.62 0.01 9.0 6.5 22-Apr-17 12.56 0.02 8.8 6.1 30-Apr-17 12.34 0.04 8.1 8.8 04-May-17 12.38 0.01 8.8 6.6 08-May-17 12.25 0.01 8.5 7.1 13-May-17 12.32 0.01 8.4 7.5 17-May-17 12.11 0.03 8.1 8.4 21-May-17 12.11 0.01 7.8 0.7 26-May-17 12.10 0.03 8.0 8.4 30-May-17 11.93 0.05 8.0 8.2 10-Jun-17 12.00 0.02 8.0 6.9 15-Jun-17 11.74 0.09 7.2 8.9 22-Jun-17 12.16 0.01 8.4 9.2 25-Jun-17 12.23 0.02 8.3 0.1 12-Jul-17 12.23 0.09 7.9 7.7 19-Jul-17 12.58 0.01 9.2 6.9 23-Jul-17 12.30 0.06 9.1 7.4 02-Aug-17 12.60 0.03 9.4 5.7 06-Aug-17 12.90 0.01 9.9 2.3