De l'observatoire russe ISON-NM
Comet Elenin continues to increase in size, and another close approach with a large Main belt asteroid
April 8th at our observatory we carried out planned observations of Comet C/2010 X1 (Elenin). An analysis of the results of the observations shows a rapid growth of the coma. Besides the internal compact gas envelope, the forming rarified external coma is also visible in the image. It’s diameter exceeds 1 minute of arc, or 80,000 km! It is possible that such a rapid growth of the coma is associated with the apparent superposition over it of the comet’s dust tail, which after opposition, still remains invisible to the Earthly observer.
The brightness of the comet also has crossed the 16m boundary, and according to the calculations of Artem Novichonok, has reached 15.4m. Such an estimate is supported by the first visual observations of the comet by Jakub Koukal and Juan Jose Gonzalez on the 4th and 5th of April respectively. It is worth noting that another well-known visual comet observer, Alan Hale, 1995 co-discoverer of comet Hale-Bopp, was not able to find Comet Elenin on April 5th with his 41-cm reflector…
In the image at left still another event is captured – the close approach of Comet Elenin to asteroid 4336 Jasniewicz. Here the closeness of the objects, which are only 11 arc minutes apart, is not an optical illusion but a real physical closeness of two celestial bodies. At the time the image was obtained, the distance between the comet and the 6-km asteroid was just 1,495,000 km (0.01 AU), which is only 3.9 times the average distance between the Earth and Moon (LD). Closest approach of the two objects was several hours earlier; they were only 1,120,000 km apart (0.008 AU).