Copyright © 2009 by G. Muler, J. M. Ruiz, and R. Naves (Observatorio Nazaret, Lanzarote island, Canary Islands, Spain)
This comet was found in the course of the Siding Spring Survey. R. H. McNaught (Siding Spring Observatory, New South Wales, Australia) was examining CCD images obtained on 2004 May 20 with the 0.5-m Uppsala Schmidt telescope. The comet appeared on four images obtained between May 20.80 and May 20.82. Although the magnitude was given as 17.7 on the first image, it ranged from 17.9 to 18.9 on the other three. The first reported confirmation came from J. Young (Table Mountain Observatory, California, USA) during May 25.45-25.48. The images were obtained with a 68-cm Schmidt telescope and CCD camera and revealed a coma 8-10" across, with no central condensation. A straight, narrow tail extended 20-30" in PA 252 degrees.
The first orbit was published by B. G. Marsden on 2004 May 28. Using 24 positions from the period of 2004 May 20-28, it revealed a perihelion date of 2004 June 16.17 and a period of 9.46 years. Marsden published a revision on June 12, which used 27 positions from the period of May 20 to June 7. The result was a perihelion date of June 16.64 and a period of 5.46 years. Following the comet's recovery in 2009, the orbit for the 2004 apparition was recalculated and was found to have a perihelion date of June 16.81 and a period of 5.50 years.
The comet attained a maximum magnitude between 17 and 17.5 in the June/July period of 2004.The comet was last detected on 2004 December 11 by astronomers at Kuma Kogen Observatory (Japan) and Konkoly Observatory's Piszkesteto Mountain Station (Hungary).
Apparition of 2009: The Minor Planet Center published a prediction on 2006 May 15 for the next return of this comet. Using 142 positions from the 2004 apparition, the perihelion date was given as 2009 December 15.52 and the period was 5.50 years. T. H. Bressi (Spacewatch) recovered this comet on 2009 April 28. The Minor Planet Center identified this as P/2004 K2 by their automatic procedures. An independent recovery was reported by G. Muler, J. M. Ruiz, and R. Naves (Observatorio Nazaret, Lanzarote island, Canary Islands, Spain) on May 1 and 3.