On Mar. 15, 2007 the well-known australian comet observer Terry Lovejoy discovered a comet in the constellation Indus. Comet C/2007 E2 (Lovejoy) presented a significantly condensed 4' coma of magnitude 9.5, which was elongated in southwestern direction. It passed perihelion during the last week of March, but approached Earth until the end of April, with maximum brightness (of about 7.5 mag) thus expected around this time (IAUC 8819/20).
During the second week of April it appeared above the southeastern horizon in the constellation Sagittarius for mid-European observers. Thereafter it will move through the constellations Aquila, Hercules and Draco into Ursa Major, thus will become circumpolar from the second week of May onwards.
Comet C/2007 E2 (Lovejoy) was the most interesting object of its class during spring 2007. Accordingly 23 reports by 8 members of the German Comet Section were received until the beginning of July 2007, although the comet was a morning object during the first weeks. For the analysis 95 international observations were included. The brightness evolution may be rather well described by the formula
m = 8.9m + 5×log D + 8.7×log r.
resulting in a maximum brightness of 7.8 mag during the days of perigee (0.442 AU on 25 April). However, this may not be the final solution discussed presented may not be the is not the final solution. Inspecting the diagram, it is obvious that the above formula does not describe the pre-perihelion evolution well. Thus it is possible that the actual maximum was a bit brighter and earlier than the formula implies.Total Brightness and Coma Diameter
The apparent coma diameter at discovery measured 2.5', increasing during the following days to 10' at perigee. Thereafter it decreased in the same way, measuring 7' at the beginning of May and 2.5' in the first days of June. The absolute coma diameter increased from 1600.000 km to 180.000 km around Apr. 20, remaining at this level until mid-May. At the beginning of June it was around 125.000 km. The coma itself was moderately condensed at first (DC 4), becoming more diffuse until the end of May (DC 2-3). Surprisingly the central condensation was rather unspectacular, incorporating only an inconspicuous false nucleus. Visual tail observations (between Apr. 22 and May 5) were very rare, not exceeding 0.2°.
Andreas Kammerer
FGK observations