Usually for a session like this, I make some sort of plan. With the high chance of rain, when at a higher elevation, observing the storms themselves can be very interesting. There was also a -5 magnitude Iridium Flare once it got dark if it miraculously cleared. And the fallback to the fallback plan was to hunt for glow worms! On several occasions, twice in the last year, while walking along the paved lanes on the Observatory grounds, I've spotted bio-luminescent glows. Upon closer examination, they came from the tail of a 4cm (1.5") segmented caterpillar! In both instances, I didn't have a camera on me, so I wasn't able to document them, and contacting a couple insect experts produced shrugs over the Interwebs... So I was going prepared this time, hoping for another encounter.
Arriving just before sunset, we found partly cloudy skies and the 20" telescope dome open with my boss in residence. He and other staffers had worked on electronics and he was about to start on the pointing model for the software. While the weather was clearing on the mountain, there were impressive thunderheads over Tucson with abundant flashing from lightning. Shown at left is the cloud buildup illuminated by the fading twilight as the lights of Tucson start to come up. Strikes like this are easy to capture with a tripod mounted camera and intervalometer. By taking 20 second exposures every 25 seconds, there is a very good chance of catching some flashes. All three of these strikes happened simultaneously...
With the clearing skies and the Iridium Flare appearance approaching, we retired to the car to set up my tracking mount. With a wide angle lens, it can take more than a minute or two for the satellite to traverse the field, so I chose to track the stars so they would be points rather than the trails from a rotating earth with a naked tripod. And since this flare would appear to be in the Milky Way, I chose my older Canon 20Da to try to catch some red-colored emission nebula. Unlike normal, I was fully set up with minutes to spare, and actually got to try some test exposures to make sure framing and focus was set. The Iridium satellites start out very faint, but I spotted it early before it entered the field, and it slowly climbed in brilliance as it reflected sunlight down to us off one of its antennae. The exposure shown here is 3 minutes in length, with a Nikon 20mm set to F/4, and I thought it came out pretty well! The Summer Triangle dominates the field, Vega at top, Altair at right and Deneb left center. Just below Deneb is the red ghostly glow of the North American Nebula, named for its shape. The irregularities in the glowing Milky Way are from dust clouds along the plane of our galaxy, and detecting them is one of my favorite activities...
Even as the lightning storms grew in intensity to the east, the glowing clouds of the Milky Way seemed to be calling to me. Since it has been June since we'd seen these starclouds at the Grand Canyon, I decided to shoot a few frames to make a little mosaic of them. Shown are the 3 frames, each a 3.5 minute exposure with the 20Da and 20mm lens as above. While Photoshop can assemble them, Microsoft ICE did a better job for me, especially in joining the seams of the frames. I love this time of year with all the dark nebulae seen in silhouette, and interestingly, another satellite was caught just below Altair, the bright star seen upper left. The dashed trail indicates that the satellite was tumbling, varying in brightness.
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I promised Melinda I'd have her home by 11:30, so I finally concluded my glow worm search, broke down my still-exposing camera and platform and headed down the mountain. Interestingly, all of my "programs" saw some action - flare, storms, stars and glow worms were all successful to some extent. Fun, fun, fun!
3 comments:
Dean, Awesome report. I love the pictures- I have been trying to learn to take some lightning ones myself and get more that are overexposed from the flash than usable...but it is a fun pursuit nonetheless!
I have also seen a glowing caterpillar atop Kitt Peak, at one of the Star-B-Ques if I recall properly. I remember a fairly small caterpillar, inch worm sized, with a number of surprisingly bright green glowing dots. Let me know if you come with an ID.
Lookin' good there Melinda.
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