C/2017 O1 (ASASSN)

DEPARTED

Type: Periodic Perihelion date: 14 October 2017 Perihelion distance (q): 1.5 Aphelion distance (Q) : 837 Period (years): 8,580 Eccentricity (e): 1.00 Inclination (i): 39.8 JPL orbit diagram COBS lightcurve The All-Sky Automated Survey for Supernovae (ASASSN) discovered a 15th magnitude comet with the "Cassius" 14cm telescope at Cerro Tololo on 19 July 2017. After considerable discussion, the IAU "Working Group for Small Body Nomenclature" (formerly the IAU "Committee for Small Body Nomenclature" and the IAU "Small Bodies Names Committee") decided to accept the name "ASASSN" for the comet The comet reached perihelion at 1.5 au in October 2017. Even before the discovery announcement JJ Gonzalez had made a visual observation estimating the comet at 10th magnitude. Several people have suggested that it must have been in outburst, otherwise it should have been detected earlier. The initial light curve suggested that it was brightening moderately rapidly, however as observations accumulated it became clear that the brightness was not increasing with solar distance. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 21-Jul-17 14.76 0.01 11.9 4.2 27-Jul-17 14.51 0.01 11.8 3.6 04-Aug-17 13.78 0.08 10.6 2.3 19-Aug-17 13.48 0.05 10.3 4.0 21-Aug-17 13.78 0.01 10.6 1.6 28-Aug-17 14.16 0.04 11.1 3.2 16-Sep-17 14.31 0.02 11.3 5.6 02-Oct-17 14.28 0.03 11.2 4.7 17-Oct-17 14.17 0.01 11.1 4.3 25-Oct-17 14.14 0.01 11.0 3.6 13-Nov-17 14.66 0.02 11.3 2.3 28-Nov-17 15.31 0.02 12.0 1.0 22-Dec-17 15.77 0.09 12.6 1.5 04-Jan-18 16.78 0.01 13.7 1.6 14-Jan-18 16.68 0.01 13.6 1.1 21-Jan-18 17.00 0.04 13.9 0.8 09-Feb-18 17.72 0.08 14.8 0.8 09-Mar-18 18.46 0.18 16.6 0.3 14-Mar-18 18.61 0.08 17.7 0.3