90P/Gehrels (0090P)

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Type: Periodic Perihelion date: 19 June 2017 Perihelion distance (q): 3.0 Aphelion distance (Q) : 9.1 Period (years): 14.9 Eccentricity (e): 0.51 Inclination (i): 9.6 JPL orbit diagram COBS lightcurve T. Gehrels (Palomar Observatory, California, USA) discovered this comet on a photographic plate obtained with the 122-cm Schmidt Telescope on 11 October 1972. The magnitude was estimated as 19 and the comet was described as diffuse, with slight condensation, but no tail. The comet was again detected on a plate exposed with the same telescope on 14 October. Although moonlight interfered during the remainder of the month, B. G. Marsden was able to calculate a set of search ephemerides which enabled Gehrels to again photograph the comet on 10 November, when the magnitude was again estimated as 19. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 30-Jul-17 17.81 0.04 16.9 0.2 06-Aug-17 17.68 0.09 17.0 0.3 24-Aug-17 17.85 0.05 17.0 0.2 26-Oct-17 17.45 0.06 16.5 0.3 14-Nov-17 17.37 0.01 15.8 0.3 25-Dec-17 17.28 0.02 16.0 0.4 13-Feb-18 18.32 0.01 17.2 0.2