Sunday, September 30, 2012

Ring of Fire

Among those celestial events observable by humans, solar eclipses have an unmistakable allure, so much so they’ve spawned an exclusive community of people called “eclipse chasers.” These adventurers research, plan, schedule, scheme, and ultimately travel anywhere in the world to be in the right place at the right time for eclipse events, especially rare total solar eclipses.

A solar eclipse occurs when the Moon passes in front of the Sun, as seen from Earth. Oftentimes the alignment is imperfect, resulting in a partial solar eclipse. However, if the Moon completely covers the Sun from our perspective, a total solar eclipse ensues. And if the alignment is good, but the Moon is at a point in its orbit where it’s too far from Earth to completely cover the Sun, an exposed ring of sunlight surrounds the dark lunar disk. This third type of solar eclipse is called an annular eclipse, from “annulus,” Latin for “ring.”

On May 20, 2012, an annular eclipse was visible from Asia to western North America, stretching across the Pacific. Fortuitously, the path of annularity, a 200-mile-wide swathe where the “ring of fire” was visible, crossed New Mexico and was centered on Albuquerque. Although at this locale the eclipse began around 6:30 p.m. and was still in progress at sunset, most of it was observable. The impending event created lots of buzz in the local amateur astronomy community, not to mention among the general public and photographers at all skill levels. Albuquerque became a destination for astronomy enthusiasts from across the country.


World map of the May 2012 solar eclipse
Line of red circles = path of annularity
Figure by Fred Espenak, NASA

My email inbox lit up with discussions of eclipse-related timings, techniques, equipment, locations, phenomena, and media misinformation. We fretted over how cloudy the western sky had been lately. We verified the next annular eclipse visible in our area would occur in 2023. We identified an upcoming (2017) total solar eclipse visible from the U.S. (rare!) and evaluated both Kentucky and Wyoming as prospective viewing destinations (Wyoming won).

My experience of the May 2012 annular eclipse, which I’ve recounted below, was a highlight of my observing life thus far. And best of all, it came right to my doorstep. If you’ve not seen one, I recommend you put it on your bucket list immediately!


Eschewing the designated public viewing site in Albuquerque where a crowd of 10,000 would gather, we were seven strong at my astronomy club’s remote observing site. I was joined by club members Jeff, Bill, and Carl, as well as two visiting amateur astronomers from the Kansas City Club and one from Florida.

The Kansas City folks were particularly thankful to be there. Arriving in Albuquerque, they had tried contacting our astronomy club through its website without success, somehow found (unpublished) coordinates for the observing site, entered them into their GPS, and started driving.

They got lost. They had no idea where they’d ended up: “in the middle of nowhere,” as they put it. After a while, a young man came along in his car. They told him they were trying to get to the astronomy club’s site. He led them through the wilderness, deposited them at the gate, and vanished in a cloud of dust. Ah, the kindness of mysterious strangers.

Like an eating-contest contender training for gluttonous excess, I had methodically prepared to cram as many experiences as I could into the hour-and-a-half-long event. It was, after all, my first solar eclipse observation, and I wanted to make it count. So I had with me four pieces of welder’s glass of varying densities, 10x50 binoculars equipped with black polymer solar filters, an 80mm refractor telescope equipped with glass solar filter and 25mm eyepiece, and a piece of plywood drilled with several 7/64-inch holes—for making pinhole projections during annularity, the fleeting Ring of Fire phase.


Welder’s glass and curious beetle


My observing colleagues also came prepared for observing or imaging the event safely, with properly filtered equipment. We scattered along the full length of the observing field, extravagant in our use of the flat, graveled expanse and its big-sky vista to the west.

Carl set up to image with a Canon DSLR, shooting through our club’s vintage 6-inch Astrophysics refractor. Brent from Florida was also imaging, with one DSLR shooting through his refractor and a second piggybacked on his mount. The Kansas City duo was observing with a 10-inch Dobsonian reflector telescope. Jeff was packing eclipse glasses and a refractor. Bill busied himself with fine-tuning the club’s new astrophotography equipment.

In my haste to get to the site, I’d forgotten one critical piece of equipment:  a hat. The bright, hot, cloudless afternoon boded well for eclipse visibility, but my deficit in headwear quickly became uncomfortable. Fortunately I was able to borrow a ball cap.

DeAnna and Leonard, a couple from the nearest town, arrived unexpectedly and parked their big truck precisely between our equipment and the Sun. Oops. At our urging, they hurriedly and abashedly moved their vehicle to a better spot. Although outfitted with their own eclipse glasses, they were nevertheless curious to see what was happening at our observing site.

And then there were nine.


Eclipse watchers
Image by DeAnna


I’d brought an atomic clock from home so I could call out countdown times to each event milestone—called “contacts.” Thirty seconds to 1st contact—the beginning of the eclipse—I single-mindedly plastered my eye to my refractor, because it would present the most magnified view.

Before I actually saw the Moon’s silhouetted disk slide into view, I noticed that something was happening on the Sun’s outer edge, a sort of subtle bubbling effect. Then the Moon took its first visible nibble, accompanied by a sudden frenzy of drumming from the crowd of New Agers who’d gathered at their ceremonial site half a mile away.

It had begun.


First nibble by the Moon - lower right, at 4 o'clock position

Throughout the eclipse, I was moving continually among my color and magnification options—thrilled alike by the unmagnified lime green view through #12 welder’s glass, the magnified-10-times deep orange view through the binoculars, and the magnified-16-times yellow gold view through the refractor. Of course, we all shared views with one another through our array of equipment, even taking turns looking through Jeff’s vintage eclipse glasses, a souvenir from the 2001 total solar eclipse he’d traveled to Africa to see. Together we witnessed the usually benign Moon relentlessly devour each of three large sunspot groups on our freckle-faced star.


  Hungry Moon advances on a sunspot


At one point, Bill said, “Hey, turn around and look at our shadows.” We twirled in unison. Replacing our familiar shadows was a menacing band of gangly creatures with hideously misshapen heads and curiously deformed fingers, rendered otherworldly by the lunar cutout.

About an hour into the eclipse, the Moon was almost entirely inside the Sun’s disk. At 2nd contact, it pulled away from the Sun’s limb (outer edge), and we had our first exhilarating look at the Ring of Fire. I moved, mesmerized, from view to view to view of that impossible ring suspended in the evening sky:  blazing, bodacious, biblical.


Ring of Fire, as seen in refractor eyepiece
Image by DeAnna


Overhead, powder blue deepened to cornflower. DeAnna held her smart phone to the refractor eyepiece, snapped an image of the ring, and crowed, “Got it!” A nearby mockingbird took a deep breath and launched into a coloratura passage of trills, whistles, and high notes. At 30 seconds to mid-eclipse, I sprinted—with perforated plywood and camera—to the sunlit side of a white travel-trailer for my first-ever experiment with pinhole projection.


With the Sun behind me, I shoot my shadow and my board's shadow on a white background.
Rings of sunlight stream through the small holes, showing the Sun in mid-eclipse.
So easy, and so fun!


A mere four minutes and nine seconds after 2nd contact, the unstoppable Moon kissed the opposite limb of the Sun for 3rd contact, the end of annularity. Planted at my refractor during both 2nd and 3rd contacts, I observed dainty Baily’s beads, one of the items on my eclipse wish list. More commonly seen during total solar eclipses, these are discrete beads of sunlight briefly shining through the valleys and other irregularities along the Moon’s outer edge, just before it pulls away from or connects with the Sun’s limb. Truly exciting to witness!

The end of annularity: 3rd contact


After the high drama of annularity, there was time for more leisurely pursuits. We looked for and spotted Venus high above the eclipse, waiting in the wings for her star turn: a very rare and much ballyhooed transit across the Sun in early June.

The Moon continued to move eastward in its orbit, slowly unmasking the Sun. Clouds drifted across the crescent Sun, flirting with the re-emerging sunspot groups. Sunset approached, and the partially-eclipsed Sun descended into atmospheric haze near the horizon. Needing less protective darkening as a result, I switched to the #11 welder’s glass, and it was just right.


Moon leaving Sun’s disk, as clouds drift by


The serrated western horizon began to gnaw on the abbreviated Sun. We knew we wouldn’t see the end of the eclipse, 4th contact, when the Moon’s disk completely leaves the Sun, because sunset would occur first.

As I drank in another long, satisfying look through the telescope, a fissure suddenly opened on the Sun’s surface. What the ???!  Realization dawned. “Jet trail on the Sun! Shoot! Shoot!” I yelled, and the imagers began clicking furiously. Big orange jack-o’-lantern grin. Shark fin. Glowing ember. Gone baby gone, ushered out with another flurry of drumbeats.


Partially eclipsed Sun with jet trail
Shark fin:  the still-eclipsed Sun sets


Do it again. Oh, do it again. Please? Finally I understand the compulsion, the addiction, the fever that grips eclipse chasers. Must. Find. The. Antidote. I hear it’s in Wyoming.

Monday, August 13, 2012

Hunting Himalia - Part Two

For Part One, click here.

My observing circle is filled with people with far more observing experience than I, people who have been amateur astronomers since adolescence, people who have forgotten more about astronomy than I’ll ever know. Q: What can I possibly bring to the table? A: Enthusiasm!

When I read or hear about an object that intrigues me, and I then find out it’s accessible to amateurs, suddenly I have to see it. I’m on fire to see it—and make sure others see it too. I do like to instigate.

I’ll mention the object casually to observing pals, talk it up, drop hints. In the process, I’ll sometimes discover that, amazingly, few to none of the seasoned veterans have seen it. That’s all I need to hear to put that object firmly in my crosshairs. In the case of Himalia, even the ΓΌber-observers of my club hadn’t seen it. Here was an irresistible challenge: pursue an object even they hadn’t seen!

I knew the Fall 2011-Spring 2012 apparition of Jupiter would be ripe for a Himalia quest. Jupiter was rising around 10 p.m. in September, and so would be high enough to begin Himalia hunting around midnight. It’s always a plus when you don’t have to stay up bleary-eyed until 4 a.m. to acquire your target. Another big plus would be the warm late-September night; no clothing layers required. Yup, this was gonna be great.

Final Prep Step #1: Assemble the Equipment

With the promise of good weather and clear skies as the appointed evening approached, the mate decided to retrieve his 24-inch reflector from storage, where it had been safely stowed since our move to the mesa. Although that may sound like mosquito hunting with an elephant gun, all that glass can help tremendously when trying to recover a 14.8 magnitude speck.

Since it’s not a tracking telescope—a motorized telescope that keeps acquired targets in the field of view by compensating for Earth’s rotation—we decided to place it on an equatorial platform, which turns a non-tracking scope into a tracking one. Although the platform is heavy and must be manually re-set every half hour or so, not having to worry about constantly nudging the scope to keep your target centered is a huge plus when you need all your concentration just to spot it.

Equipment Checklist
  • 24-inch f3.9 home-made reflector (aka “The Cannon”)
  • Osypowski equatorial platform
  • 13mm Nagler eyepiece
  • 4.5-inch Starblast with 24mm eyepiece (used as a finder scope on the 24-inch)
  • Ladder
  • Jellybeans
"The Cannon"

Equatorial Platform

Final Prep Step #2: Assemble the Experts

With the mate—a more seasoned observer—at my side, I had substantially increased my odds of success. While setting up at our astronomy club’s observing site, we pooled resources by reeling in Kevin, a very accomplished observer who also had Himalia on his life list and was keen to try for it. Kevin was familiar with the motions of Jupiter and its moons, which proved extremely valuable in our shared quest.

The Main Event

At the appointed hour, the mate re-set the equatorial platform to get a full 30 minutes of accurate tracking, and then aligned his telescope using his NGC-MAX (a computer controller that aids in locating objects). I read off the RA and DEC coordinates for Himalia from my ephemeris (see Part One) and he tapped them into the NGC-MAX. He inserted a 13mm eyepiece in the focuser, as we had determined that the field of view produced would be a good match to the field shown in the DSS image.

After pushing the cannon-like scope to the coordinates, he climbed the ladder to the eyepiece clutching the piece of paper with the DSS star field image. After rotating the paper once to the right, the image matched what was in the eyepiece. A few bright stars in a triangle pattern and a three-star arc within the target field helped. Piece of pie!

He then set out comparing the DSS image to the eyepiece view, star by star. Finally, he was left with one star in the center of the field of view that was not represented on the DSS image. It had to be Himalia, didn’t it?

I climbed the ladder next, and using the DSS image, was easily able to tick off the brighter stars in the field, including the triangle. I made my way incrementally to each dimmer star in the field, but was only able to see the top star of the three-star arc. I couldn’t see the two dimmer stars below it. I waited to let more light integrate on my retinas. And then using averted vision, I saw the central speck that wasn’t on the DSS image. The mate confirmed that it was dimmer than the top arc star but brighter than the two lower arc stars, which explained why I could see Himalia, but not the lower arc stars.

Himalia was seen at tip of arrow

We huddled to confer. It couldn’t be just another star in the field that was too dim to be represented on the DSS image, because it was brighter than the two lower arc stars, which were on the image. It had to be Himalia, didn’t it?

Kevin mounted the ladder next. He easily spotted the “interloper” star in the field. We discussed whether we could see it move that night. Observed movement against the background stars would be verification that it was no star. Based on how much the RA & DEC coordinates on my ephemeris changed over time, it seemed likely. In fact, Kevin predicted that, if we waited about an hour, we would be able to see motion. With his knowledge of the current motions of Jupiter & Company, he also predicted in which direction we would see the Himalia candidate move.

I kept thinking: can it really be this easy? Rick Scott’s article (see Part One) had made this target sound so daunting. As it turned out, what we had—that the author didn’t—was aperture, 24 inches compared to his 10 inches. It made all the difference.

We waited about an hour to see if the suspected moon moved against the background stars. Sure enough, it had shifted westward, moving in the direction Kevin had predicted. Eureka! Himalia was ours!

I was only able to see Himalia with averted vision, that is, by using my peripheral vision and looking at a spot in the black sky right above it, rather than directly at it. My two observing partners were able to see it with direct vision, the second time they looked at it. This is because  1) Himalia was then a little higher in the sky and less obscured by Earth’s atmosphere, and  2) their eyes are annoyingly better than mine. Given Himalia’s faintness, I was suitably impressed with Rick Scott’s accomplishment, spotting it with far less aperture. How did he do it?

Although it was exciting to observe such a tiny fleck of reflected light, one of the best views of the night, for me, was when I looked at Himalia and couldn’t see it. Let me explain.

Starblast (little blue scope) riding piggyback as a finder scope

We were using a 4.5-inch Starblast, a nice little telescope in its own right, as a finder scope (targeting tool), riding piggyback on the 24-inch scope and aligned with it. The view through the finder provided a much wider field of view and much less magnification than the big scope. I could therefore see Jupiter and all four Galilean moons, with a lot of black space around them. Himalia was centered in the big scope—and staying centered because it was tracking. So when I looked through the finder, I knew that Himalia, although I couldn’t see it with such low magnification, was dead center in the field of view. That allowed me to see the big picture, where Himalia was in relation to its host planet.

I knew Himalia was considered a “far-ranging” moon; indeed, most moons in Jupiter’s large harem have far-ranging orbits. Himalia floats through space about seven million miles from Jupiter. Compare that to the orbit of Earth’s Moon, a mere quarter of a million miles from its parent planet. The view through the finder confirmed Himalia’s lonely orbit: it was more than one degree from Jupiter, far from the mother ship and its four famous satellites. A degree in the sky is two times the width of a Full Moon as observed from Earth.


Four other seasoned observers on the field that night—Dave, Bob, Ed, and Vance—came over for their first look at Himalia. This is what I call “giving back”: for all the fabulous views of remarkable objects offered to me over the years and for the unfailing generosity of the amateur astronomy community.

Hunting Himalia was team astronomy at its best, and we seven could now say we had “been to Himalia”!