An Arizona amateur appears to be the first person to spot Comet ISON again after its long spell in the solar glare. Bruce Gary used an 11-inch telescope to photograph a faint bit of fuzz at the correct position in Cancer the Crab below the constellation Gemini. Since ISON was only a few degrees above the horizon and twilight already underway, this was quite a feat. Gary is still awaiting confirmation that his pictures really do show the comet and not some camera flaw, but it appears to be the genuine item.
We can all breath a sigh of relief that ISON has survived this long. It’s been out of view of ground-based telescopes since late May when Earth’s orbit put the sun between us and the comet. Lost in the glare of day and twilight, no one knew exactly what our celebrity was up to. For all we knew, it had broken up in to pieces and disintegrated, an infuriating habit shared by many comets.
Gary’s photo is important for another reason. It gives astronomers another precise position they can plunk into their computers to better calculate ISON’s orbit. Not that the comet’s going to veer off in another direction but activity on a comet’s surface – the vaporization and jetting of ice and dust – can subtly alter a comet’s predicted path. The more observations, especially ones like Gary’s coming after a long data drought, the better we can keep track of ISON’s future moves.
So how bright is this thing? Astrophysicist Karl Battams notes that the comet appears to have brightened according to predictions. That would put it between 12.5-13.0 magnitude. If ISON were high in the sky, amateur astronomers with 10-inch and larger telescopes would have no problem spotting it, but our favorite fuzzball still lingers low in the northeast near the start of dawn. Thick hazy air near the horizon dims it another 2-3 magnitudes.
Atmospheric seeing – the steadiness of the air – gets worse the lower you look, turning stars and comets alike to mush. Someone with a fairly large telescope will soon enough see it with their eyes as opposed to recording it in a photo.
For the Upper Midwest, ISON is 4 degrees high at the start of dawn tomorrow morning, too low to spy in most amateur telescopes. But hang in there. Once the waning moon and its aura of glare leave the scene at the very end of August, conditions quickly improve. Assuming the comet continues to brighten, anyone with dark skies, a good map and an 8-inch or larger telescope should get their first look at this much-anticipated object.