53P/Van Biesbroeck was
discovered with the 61-cm reflector at Yerkes Observatory by George van
Biesbroeck on September 1st 1954 as a 15th magnitude object. The comet
was observed for over a year, but there was some difficulty in calculating an
exact orbit for it. It was not until 1958 that definitive elements became
available. The comet is unusual in the sense that its orbit is very close to a
1:1 resonance with Jupiter, in other words, it has almost exactly the same
orbital period as Jupiter and is currently “locked” in position. The current
period is 12.5 years, with perihelion at 2.42AU.
This is its fifth observed
perihelion pass in 2002 (Perihelion being reached on October 9th)
after the 1954, 1966, 1978, and 1991 passes. The comet is notable because it
appears to have shared an orbit with 42P/Neujmin
3 in the 19th Century before a very close approach (0.04AU) to
Jupiter. Calculations
by Lubos Kresak suggest that the two comets appear to have split some time
around 1850 and to have evolved into independent objects, before a close
approach to Jupiter in 1850 the two objects had orbits that were identical to
the limit of accuracy of the calculations.
The light curve brightens
as a 10th power law, much slower than many short period comets. This
shows that it does not have the thick surface dust mantle that suffocates the
activity of more evolved comets.
Maximum will be reached
around magnitude 14 in June 2003, well before perihelion, when the comet is at
opposition and hence closest to the Earth. As it moves away from opposition the
comet will fade considerably as the geocentric distance increases. At
perihelion it will be 1AU further from Earth and approaching conjunction.
CCD observations in a 10
arcsecond aperture from: