Saturday, December 14, 2013

Lovely Lovejoy - First Look!

While the potential "Comet of the Century", C/2012 S1 ISON got pulverized as it passed over the Sun's surface on Thanksgiving and has disappeared, there has been another with greater staying power - C/2013 R1 Lovejoy.  Discovered by Terry Lovejoy in Australia just 3 months ago, it is currently barely visible to the naked eye from a dark site ( I mean that - barely imagined from a really dark sky!).  While I've spotted it from the back yard in binoculars knowing exactly where to look, nothing beats the view of these things from a dark sky, but as it is a pre-dawn object, I've not gone for any early-morning drives...

But with the nearly-full Moon upon us, this morning was the last chance to have a dark sky for an hour after moon set and before twilight starts, so pulled the trigger and drove up Mount Lemmon north of Tucson to San Pedro Vista with a clear, dark sky in the northeast.  Leaving the house at 1am reminded me of the "olden days" when as a pup of 43 years of age, I would head up the mountain about every third or fourth morning to shoot Hale-Bopp in the morning sky with a Schmidt Camera back in the spring of '97, and believe me, I felt it in my bones these 17 years later!  Arriving well before moonset, I set up 2 mounts and 3 cameras running 80mm to 480mm focal length.  Here are some quick-and-dirty results.

Interestingly, it was also the peak of the Geminid meteor shower, and the skies really were ablaze with meteors.  I was sticking to the task at hand, so never set up a camera with a wide-angle lens, but believe me, would have been like shooting fish in a barrel!  While not even looking away from the quadrant of the sky where the comet was located, I'd see 2 or three over 5 or 10 seconds!  I'm thinking it was easily a couple hundred per hour over the entire sky...  The dark sky really helps with that.  Interestingly, 2 of my early shots with the wide-field 80mm caught Geminids on consecutive frames, so stacked them here.  Comet Lovejoy is sporting a very nice tail (also visible in binoculars) just south of the Keystone of Hercules.  The grand globular star cluster M13 is visible on the left side as well, and made a nice contrast to the comet.  I'm thinking the comet was just brighter than the cluster, but not by a great amount...  Since the comet is so low, the fast lens (Canon 80mm @F/3.5) also caught some airglow (the greenish tints), and possibly some very thin cirrus.  North is at the upper left corner...

One of the other rigs I set up was the little Meade 80mm F/6 triplet APO lens (480mm focal length).  Shown here is a stacked set of nine 150second exposures. Taken with a Canon XSi (my normal go-to camera), north is approximately up in this exposure, whose field of view is small enough that it doesn't even show Xi Hercules at the left of the comet in the wide-field above...  The comet is moving pretty quickly, and I stacked the picture on the overexposed head of the comet, so the multiple-star trails demonstrate how far it moved in the nearly 3 minutes between exposures.  The colors are real - the greenish glow in the coma is from dissociated carbon molecules from the nucleus, and the bluish glow of the ion tail is from the fluorescence of water vapor and carbon monoxide driven back by the solar wind.

The hour of darkness between moonset and start of twilight passed all too quickly, and I packed up all the gear and drove back down the mountain to Tucson, arriving home just after sunrise.  It made for a long night, and sleeping till 1pm, but it was worth it to see this stand-in for Comet ISON do such an admirable job as substitute.  And this fellow isn't going anywhere soon - it will stay at the limit of naked-eye brightness for another month in the morning sky, and even into the Spring and the Grand Canyon Star Party, a dedicated hunter with a C-14 might be able to show it to tourists as a barely-visible speck.  In the meantime, I'll look at these exposures more carefully and see if I can get out something a little more interesting...

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