Comet Elenin C/2010 X1

This would certainly have to be considered among the more eagerly-awaited
comets of recent years. It was discovered last December by Russian
astronomer Leonid Elenin using a remote-controlled telescope in New Mexico;
at that time it was a dim and distant object but has been steadily
approaching the sun and Earth ever since. It was at opposition in mid-March
and I successfully imaged it as an object of magnitude 15 1/2 to 16 later
that month. I also began visual attempts around that time, but the comet
remained elusive for the next two months. Finally, I picked up a very faint,
diffuse, and "soft" suspect on the evening of May 23, and was able to verify
this as being the comet by observations over several subsequent nights.
(Because the comet was at its stationary point at that time there was hardly
any motion from night to night.) On May 24.19, m1=14.4, 0.7' coma; on May
31.18, m1=14.2, 1.1' coma.

The comet is traveling in a remarkably low-inclination orbit (inclination
1.8 degrees). It remains in the evening sky up through perihelion passage on
September 10 (at which time its solar elongation will be 26 degrees),
however after that it passes almost directly between the earth and the sun
in late September and then rapidly emerges into the morning sky during the
first week of October. It travels rapidly towards the west-northwest and
passes 0.23 AU from Earth on October 16; by early November it enters Taurus
and is at opposition shortly after the middle of that month before crossing
the northern section of the Pleiades star cluster on November 23. The comet
enters Aries at the end of November and remains there for the next two
months.

Comet Elenin possesses the potential to be a relatively bright, perhaps even
conspicuous, naked-eye object. However, it is currently running quite a bit
fainter than the original expectations for this time, and furthermore
calculations have now shown that it is making its first visit into the inner
solar system from the Oort Cloud; such comets tend to under-perform as they
pass through perihelion. A cautiously optimistic projection based upon its
present brightness suggests a peak brightness of 5th or 6th magnitude during
September and October, although it could well be one or two or more
magnitudes brighter, or fainter, than this. There is a possibility of a
fairly strong brightness enhancement due to forward scattering of sunlight
when the comet passes between the earth and the sun in late September,
however this will probably be quite brief and, more importantly, the comet's
elongation from the sun will be very small. (On the other hand, it should
make for a spectacular show in the LASCO coronagraphs aboard SOHO.)


Description at http://www.earthriseinstitute.org/coms48.html#487

Images and reports (including reports of outreach efforts) are welcome.


Sincerely,

Alan