C/2009 P1 (Garradd)


Type: Hyperbolic Perihelion date: 23 December 2011 Perihelion distance (q): 1.6 Aphelion distance (Q) : n/a Period (years): n/a Eccentricity (e): 1.00 Inclination (i): 106.2 JPL orbit diagram COBS lightcurve Gordon Garradd discovered a 17th magnitude comet on images taken during the Siding Spring Survey with the 0.5-m Uppsala Schmidt on 13 August 2009. The comet reached perihelion at 1.6 AU in December 2011. Visual observations were reported in 2010 August, with the comet already 13th magnitude. It had reached 8.5 by July 2011, although the rate of brightening was relatively slow. It reached a first peak of around 7.5 towards the end of August, though some observers continued to record it brightening for another month or two. This perhaps implies that not all observations are independent, and there is a certain amount of "following the trend". It was widely observed during the first half of 2012, reaching 6th magnitude at its brightest. Brian Marsden noted on MPEC 2009-S147 [2009 September 30] that the "original" and "future" barycentric values of 1/a are +0.000446 and +0.000192 (+/- 0.000389) AU^-1, respectively. The moderate "original" value shows that this comet may have made a previous visit to the inner solar system. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 31-Jan-13 16.40 0.04 12.6 0.1 29-Mar-13 17.67 0.06 16.0 0.2