Only 15 observations of 3 members reached us from comet 78P/Gehrels 2. For the analysis 110 international estimates were added. These show that comet Gehrels 2 was 3 mag brighter than expected during the whole apparition. It peaked at 11.5 mag in mid-December 1997. Remarkable too is the very small brightness decrease during the first half year since perihelion passage. As a result, comet Gehrels 2 was visible in amateur telescopes even in March 1998. The brightness evolution can be described by the formula
Total Brightness and Coma Diameter
Whereas the absolute coma diameter was constant at 100.000 km, the apparent coma diameter increased from 1.2' to 1.5'. Very constant too, was the degree of condensation, at DC 3.
Andreas Kammerer
Observations