This comet was the second of four visual comet discoveries to be made so far in 2002, showing that visual comet hunting is back in mode again. Comet Snyder-Murakami was discovered on March 11th by Douglas Snyder and Shigeki Murakami. Snyder observed it with a 50cm f/5 reflector from Palominas (Arizona) and Murakami from Matsunomiya (Niigata, Japan) with a 46-cm f/4.5 x68.
The comet was large and difuse and difficult to estimate, as witnessed by the fact that Snyder estimated it as magnitude 13 and Murakami as magnitude 11. This difficulty was highlighted by the visual confirmation of Alan Hale the following night who estimated it as magnitude 10.4 visually, but 11.5-13.0 with a CCD.
The comet was found to be receeding from perihelion at discovery. Perihelion was reached on February 21st 2002 at 1.47AU from the Sun. Prior to perihelion the comet was close to the South Celestial Pole and moved exactly along the Milky Way from Carina to Aquila between August 2001 and March 2002, making visual or CCD detection complicated.
The orbit is very slightly hyperbolic (e=1.0005) with an inclination of 93º.
The light curve
There is considerable dispersion in the light curve because the comet was fairly large and very difuse making estimates very dependent on the sky conditions and the instrument used, quite apart from the experience of the observer.
Faustino García estimated the Degree of Condensation as DC=0 - totally difuse. We also see that there is a 3 magnitude difference between the CCD estimates and the total visual magnitude which, for a comet only 3' in diameter, indicates that it was very difuse with little or no concentration of light in the centre.
Although the absolute magnitude is nominally quite bright (5.5), this is mainly due to the fact that the comet faded very rapidly with increasing heliocentric distance.
CCD observations in a 10 arcsecond aperture by:
CCD aperture photometry in apertures of 0'.2, 0'.8, 1'.0, 1'.1, 1'.2, 1'.4, 1'.5 by:
Visual data by:
Última actualización 19/01/2003