Last December, comet-lovers got a bit of an adrenaline rush when they learned that a new object, Comet Elenin (C/2010 X1), might reach naked-eye brightness a week or so after it reaches perihelion on September 10th.
It's still early in the game, but reports from visual and photographic observers over the past few weeks have tempered expectations somewhat.
Those looking for Comet Elenin by eye have found it elusive. Only two observers — Jakub Koukal, using a 9½-inch (24-cm) reflector in the Czech Republic; and Juan José González Suárez, using an 8-inch Schmidt-Cassegrain in Spain — feel certain they glimpsed it by eye in early April. But it was a no-show for comet-hunter Alan Hale, who had a larger telescope at a pitch-black site 7200 feet (2200 m) up.
Another consideration is that the visual estimates (magnitude 15.3 and 14.9, respectively) are at odds with CCD observations suggesting something no brighter than magnitude 16. Such differences would make sense if Comet Elenin were somewhat diffuse, but everyone agrees that it's strongly condensed and almost stellar in appearance.
Koukal and González are veteran observers who carefully checked their sightings against faint nearby stars. Even so, former S&T columnist John Bortle, who's watched comets come and go for more than 50 years, is skeptical of visual sightings made at the hairy edge of a telescope's capability. "I can cite many instances of 'positive' observations turning out to be spurious, even when made by experienced observers," he notes.
For now, who can or can't see it doesn't matter much, as the interloper is still heading inward and won't get seriously worked up for several months. But the comet cognoscenti have already started calling it "intrinsically faint," and it's becoming clear that hopes for a nice eyeball-easy showing have dimmed considerably.
Best guesstimates now suggest that Comet Elenin's total brightness might peak near magnitude 6 in mid-September — a nice binocular object — presuming that it survives its dash through perihelion just 45 million miles (0.48 astronomical unit) from the Sun.
Meanwhile, you have my permission to ignore or refute any of the wacky postings about the supposed danger posed by Comet Elenin. All this nonsense seems to have started back in January, when edge-of-reality blogger Laura Knight Jadczyk made provocative warnings — all based on information from a member of her research team who's "an astronomer at a large observatory". (Yea, right.) It's not even worth giving you a link to her ramblings.