Saturday, August 13, 2016


The word came out on Tuesday (thanks to the IAU telegrams I get at work via e-mail) - this year's Perseid meteor shower might show enhancements due to Jupiter perturbing the dust streams released from comet 109P/Swift-Tuttle (the source of the Perseid meteors) closer to Earth's orbit. In addition, we might encounter the narrower streams of dust released in the comet's one-orbit (1862), four (1479) and seven-orbit (1079) passes through the inner solar system. Predictions favored Thursday night about 9pm - a little early for the desert southwest as the radiant would still be low or below the horizon. In addition, the bright moon would be up till a little after midnight. Oh, and we're having a more-than-active monsoon system and there was a 40% chance of rain that night!

But even with Melinda still in the hospital, I got thinking about the chance to go out and see some meteors in a dark sky. While normally just the dark sky is enough to get me out, but add the natural fireworks, and wowser - more fun than humans should be allowed to have!

Fortunately, Melinda was released on Wednesday, and after a night at home with the both of us, I felt comfortable leaving her in sister Maj's care for a few hours. Plus, with the late moonset, I wouldn't be leaving the house till after 11, normally after she is tucked into bed. Oh, and the weather - there were a few clouds into the sunset, but it was mostly clear - the trip was on!

I figure if you are headed to dark sky, go all the way, so headed west (fewer clouds in that direction at sunset) towards Kitt Peak. Once there, I could set up at the base of the mountain, or head up to my little observing site near milepost 9. Once I arrived, there were a collection of a few cars at the base, so I headed up the mountain where I encountered no one - likely turned back by the "road closed" sign, which I ignored... I did pass some places were gravel was washed over the road - indicating to me that heavy rains had been here a day or two before - perhaps an ominous warning. Sure enough, when arriving at the observing spot on the SW corner of the mountain, there were alternating periods of clouds, fog and clear as they formed right at the 6,000 foot level! I set up anyway, and here show the interesting juxtaposition of stars, clouds and fog over the site. Then, a few minutes later, I captured my first Perseid just over the hill to the east. Both of these are ultra-wide-angle shots with the 14mm Rokinon lens on the full-frame Canon 6D sensor. While sky coverage is huge, any meteors are going to be tiny!

But after a few minutes it got to be frustrating as time was wasted waiting for clear spots to return. I moved everything back in the van and moved down to a pullout near the 4500 elevation level near milepost 5. Here conditions were near perfect. I re-set up the pics I had started at the higher site - with an 85mm (re-purposed Nikon lens on the Canon 6D!). I centered the trio of the Andromeda Galaxy (M31), the Triangulum Galaxy (M33) and the cluster NGC 752. Then you cross your fingers for a meteor or two! Well, in the 5th exposure of 30 one-minute exposures, my stars aligned and got my one shot, shown at left. At center is the orange-y star Beta Andromeda, with the fuzzy objects as above, clockwise from upper right.

Likely the brightest meteor I captured is shown at right, cropped from a shot with the 16mm (Nikon again) fisheye in Pisces. What the camera captures here that was not obvious to the naked eye was the gentle glow of the zodiacal band crossing from bottom center to upper right, contrasted with the rising Winter Milky Way.

That also explains why, in my next set of exposures with a 50mm lens (again, a fast Nikon from the film days) of the Taurus area seems to be awfully bright as the normal glow of the Milky Way is "contaminated" by the Zodiacal glow and also likely some sky glow from Tucson over the hill... In this shot at left, the Pleiades and Hyades clusters are at right, and the red smudge at top center is the California Nebula hydrogen cloud. Not bad for a 60 second exposure!

I also ran a second camera, Melinda's T1i - newer and likely less noise than my XSi... I ran it most of the time with the all-sky lens, an 8mm (again, Nikon) at F/2.8.  But like I pointed out before, with the ultra-wides, the meteors are so small they tend to get lost. Check out the shot at right - the standard untracked 2 minute exposure. While it looks clear of meteors, there is a little one to the right of the Pleiades at far right! It seems that even at F/2.8, short focal length lenses are at a disadvantage of capturing meteors. It seems longer, fast lenses have an advantage...

The last thing I want to say about the Perseid display is that it was amazing how many of them seemed to come in pairs! At least a half dozen times while I was out, I'd see one flash, then a second one right next to it a second or two later! I can't explain it other than the statistics of small numbers... As for the overall display - it seemed that if you were at the right place, the 240/hour that was predicted was realized in some places in Europe. See the sites here for visual observations, and look at this one the Japanese did for radio observations (meteors create an ionized trail that temporarily reflect radio waves). I didn't do a count, since I was preoccupied with cameras, but given that so many came within seconds of each other, it was certainly way over the standard 80-100/hour, IMO...

Shortly before twilight was to start, clouds started forming just over my head to the west, so took that as a sign it was time to go! I packed in record time and hit the road about 4am and was walking back to bed right at 5am. Two full hours of sleep and it was time to do the cat chores and get Melinda packed up for her morning cancer center appointments! Sleep is for wimps! Anyway, I slept well the next night and almost feel back to normal today - happy for a few hours under some dark skies!

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