Dust production and coma morphology of 67P/Churyumov-Gerasimenko during the 2002-2003 apparition

Light curves and images of 67P/Churyumov-Gerasimenko are presented for the 2002-2003 apparition based on amateur CCD monitoring using a standardised method to produce consistent photometry in Johnson-Kron-Cousins system. Multiaperture data shows a large outburst at perihelion during which dust production increased by a factor of 2 to give a peak value of Afrho approximate to 350 cm. A similar outburst was seen at the same epoch of the previous apparition in 1995-96 and probably in 1982-83, suggesting that the light curve is similar at successive returns. A considerable change is seen in the slope of the light curve at r = 1.85 AU (T + 140 days) corresponding to a second significant increase in dust production. Overall though the dust production shows a very steep dependence with heliocentric distance, falling as r(-5.8).