Analysis of past comet apparitions

C/1999 S3 (LINEAR)


A LINEAR object of magnitude 13.5 was discovered on Sep. 24. During follow-up observations comet C/1999 S3 (LINEAR) showed a 0.7' coma with a 15m faint nuclear region and a tail up to 3' long at PA~220° (IAUC 7264).

The developement of this comet was more positive than expected. Based on the 17 observations of 3 FG members and 140 international observers, the brightness was 0.5m higher than predicted. The brightness development prior to perihelion shows a time dependency, probably indicating a late activation of the comet's nucleus. After the perihelion a normal dependency from the sun's distance is observed:

pre-perihelion: m = 11.7m + 5×log D + 0.016×|t-T|

post-perihelion: m = 8.8m + 5×log D + 9.5×log r

According to this the maximum brightness of 12.1m was reached at the beginning of November. The apparent coma diameter increased slightly from 1.3' at the beginning of the apparition to 1.6' in November 1999 but was down to 0.8' at the end of February 2000. The absolute coma diameter was in the order of 70.000 km at first, reaching a maximum of 100.000 km at the begin of December 1999, only to decrease to the primary value again until the end of February. The comet was well condensed at first (DC 5-6), getting more diffuse continually until the end of February, reaching a degree of condensation of only DC 3. A small number of observers reported a 1-2' short tail pointing east.

Total Brightness and Coma diameter

Andreas Kammerer

FG-Observations


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