C/2002 R3 (LONEOS)

Discovered by LONOEOS, the Lowell Observatory Near Earth Asteroids Survey on September 4th 2002 at magnitude 18.2, this object is a rather large comet at a high heliocentric distance. The comet will pass perihelion on June 13th 2003 at 3.87AU from the Sun. Due to the very large heliocentric distance the comet will only reach about 15th magnitude. The comet has a retrograde orbit with an inclination of 161º.

The light curve

This appears to be a new object fallen from the Oort Cloud and there are already indications that it is brightening very rapidly, possibly as fast as an 8th power law. Due to the changing geocentric distance which will be a much larger factor close to perihelion than the heliocentric distance the comet's light curve will be dominated by its position relative to the Earth, with the brightest magnitude at opposition. This will lead to a maximum in December 2002, followed by a significant fade and a new maximum in late 2003, well after perihelion.

We can see the initial very rapid rate of brightening in the light curve typical of a new and very gassy comet. This though turned into a rapid fade as opposition was reached and the comet started to recede from the Earth. The observed rate of fade is though much faster than can be accounted for by the increase in geocentric distance.


Observations by:

  • Ramón Naves & Montse Campàs - MPC 213
  • Josep Lluis Salto - MPC A02

Image: December 6th 2002

Image of C/2002 R3 (LONEOS) taken with a S/C 0.25-m f/3.7 Schmidt-Cassegrain + CCD from Abrera, Catalonia (Spain).

The comet is captured passing close to the magnitude 15.5 spiral galaxy, UGC1432.

Josep Lluis Salto

MPC C02, Abrera. Catalonia (SPAIN)


Coma profile: January 24th 2003

Profile of the coma of C/2002 R3 (LONEOS).

Obtained by CCD photometry with apertures of 10, 20, 30, 40 and 60 arcseconds.

Ramón Naves & Montse Campàs

Última actualización 25/01/2003
Por M.R.Kidger