The Nucleus of Comet 48P/Johnson
Abstract
We present new observations of short-period (Jupiter family) comet 48P/Johnson taken over several months when near ~4 AU heliocentric distance. CCD photometry shows that this object has a pointlike inner surface brightness profile. It varies cyclically in brightness, with a light-curve period 14.50+/-0.02 hr and photometric range ΔmR=0.32+/-0.05 mag. We attribute these variations to the rotation of a bare, aspherical nucleus with projected semiaxes 3.0×2.2 km (0.04 albedo assumed) and (two-peaked) rotation period 29.00+/-0.04 hr. The phase coefficient of the nucleus is 0.059+/-0.002 mag deg-1, consistent with a low-albedo surface. A faint tail is evident in a deep composite image but appears to contribute little to the nucleus signal.
- Publication:
-
The Astronomical Journal
- Pub Date:
- March 2004
- DOI:
- 10.1086/382097
- Bibcode:
- 2004AJ....127.1784J
- Keywords:
-
- Comets: General;
- comets: individual (48P/Johnson);
- Kuiper Belt