|• C/1999 S4(LINEAR)
At last I can present a photograph of LINEAR. I detected some change to the shape of the coma when I observed it with the 60cm telescope on July 7. I also noticed complex changes to the tail and thought some sort of eruptions occurred. However, nothing was detected in successive photographs. In mid-July I received a report from Mr. Okamura that the effect of non-gravitational forces had begun to be seen with 5" deviations from the predicted orbit. Mr. Okamura is a dedicated researcher on various phenomena related to comets and this is his first significant finding. Non-gravitational forces refer to abrupt eruptions of gases (a kind of rocket propulsion), which move the object off the predicted path. The unusual behavior of this comet on July 7 may have something to do with non-gravitational forces. It was probably the precursor of the impending disintegration of the comet. For those who compute the comets' orbits, it is thrilling to see how the orbit changes, though changes may be minute. I am looking forward to turning the telescope to it.
The photograph by the 60cm telescope shows the enduring appearance of LINEAR prior to its demise. The telescope was locked onto the comet and guided for a 10- minute exposure.
10-minute exposure on Fuji Color Reversal 400 film on July 21, 2000
By Metcalf guiding with the telescope aligned to the comet
60cm reflector at Geisei Observatory
Copyright (C) 2000 Tsutomu Seki.