Oregon Star Party, Part 2

Observing

by Matt Tarlach

In between the lectures, telescope tours, swap meet, and socializing with over 600 fellow stargazers at the OSP, we did find time to do a little observing.

We pulled in at a little after 4 on Thursday afternoon, and took about 3 hours to pitch camp and assemble the various scopes we had brought to demonstrate. The first night we set up a VX102 Fluorite refractor on a GP mount & pier, a 150mm f12 Maksutov Cassegrain on a GP-DX & tripod, a 6" Skyquest XT dob, and an 80mm Short Tube. Some high level clouds obscured the eastern portion of the sky as darkness fell. After getting everything set up and collimated, we began the evening's observations by looking at some double stars, our intention being to bide time until the sky became fully dark (and hoping that transparency would improve). It turned out we had so much fun we stuck with the doubles well into the night!

For the past several months, Ken has been working toward observing all the objects listed on Orion's DeepMap 600, so we turned to the list of of double stars printed there. As we spent much of our telescope time over the weekend sharing the views with star party attendees trying out the Orion products, I wasn't able to keep a proper log. So I'll just list what we checked off, along with the DeepMap description, and add whatever impressions I recall:

We hadn't meant to get so carried away with the doubles, but they were looking so good it was hard to turn away! Finally we turned the scopes toward a variety of late summer Messiers and were rewarded with some fine views of old friends until about 12:30. Unfortunately the clouds were spreading from East to West as the evening wore on, and we were getting tired after the long drive and rush to set up. So after a visit to fellow TACo John Rostoni, observing across the road with his 10" LX200, we packed it in for the night to rest up and hope for clearer skies. When we awoke the next day, we heard reports that the skies had cleared about 3AM, and the hardier observers still awake were rewarded with black, steady skies until sunup.

Friday dawned clear, and it remained bright and dry all day. I didn't hear any humidity readings but the daytime sky was so transparent that through my polarized sunglasses it was deep purple near the zenith. We put a white-light solar filter on the 4" Fluorite, and were rewarded with spectacular sunspot detail and granulation. One dark grouping appeared like a three-toed footprint, surrounded by an irregular, swirled bright area. Ne ar the speakers' tent, two observers had set up H-Alpha filters. One setup, consisting of a Tele Vue Genesis SDF with focal extender and 0.7 angstrom bandpass Daystar T-Scanner, offered the most thrilling views of the sun I've ever enjoyed! Prominences of varying morphology stood out from every limb and long, curving, dark lines crossed the solar surface, which was deeply textured with what looked like granulation (not sure if it is really the same phenomenon as seen in white light).

As evening fell the skies remained crystal clear, and we set up the 4" Fluorite, 6" f6 Maksutov Newtonian, and 80mm Short Tube with high hopes. After "warming up" with the Double-Double and Ring Nebula in Lyra, we turned toward Sagittarrius quickly slipping away in the West. Again we had many visitors who wanted to try the scopes on display, so we hopped up the Milky Way from M7 skimming the Southwestern horizon to the Dumbell nearly overhead. I had looked at most of these objects earlier in the Summer in my 12.5", yet they were showing up so well in the 4 and 6" scopes we had deployed that I became convinced of the excellence of the site at Indian Trail Springs.

The previous night the darkness had been emphasized in a backhanded way: without any earthly lights illuminating them from below, the clouds blocking the Milky Way had been the blackest I'd ever seen! On Friday evening, the transparency was evident in the glorious, 3-dimensional appearance of many familiar objects, including the Lagoon, Trifid, and Swan nebulae, and the Wild Duck Cluster. Even at low power, under which the background sky will appear gray and washed out from lesser sites, the contrast and snap of the images was remarkable. On Saturday night I would sit down with my atlas and do a naked-eye limiting magnitude check: above about 60 degrees altitude there was no star plotted in the Cambridge Atlas (limiting mag 6.5) that I could not detect, yet I could not confirm detection of any stars not plotted...for an easy limiting magnitude determination of 6.5. My vision is not particularly sensitive; when I've participated in group tests at past TAC events, keener eyes like Mark W's have consistently seen 0.5 to 0.7 magnitudes deeper than me. In any case this was the deepest limit I've ever achieved, better by about 2 tenths than my previous best at Bumpass Hell. FWIW, seasoned OSP regulars described sky conditions in 1999 as average for the site, at best. But I'm getting ahead of myself...

After spending the first couple of hours of darkness Friday on bright showpieces of the deep sky, we turned both scopes to Jupiter to watch a transit of Io that had begun an hour or so earlier, about the time Jove rose like an airplane floodlight in the East. The first look blasted our dark-adapted eyes, but after recovering from the dazzlement we observed Io's shadow marching across one of the giant planet's equatorial belts. As the planet rose higher in the sky, the seeing steadied, and we hoped to get a look at Io itself. We looked carefully, especially at the moment when the moon was supposed to be transiting Jupiter's meridian. We both noted a lump in the equatorial band opposite Io's shadow, which may have been the orange moon, but were never able to declare the detection with certainty. (For those who may be reading this with an eye toward the performance of the Orion scopes, I should point out that neither Ken nor I are very experienced planetary observers. Rich or Jay or many others might have made the detection at a glance in the same instruments.) In addition to Io's shadow, we noted at least 3 blue festoons and several white ovals on the planet itself. The most low-contrast detail was revealed by the 6" Mak-newt, mostly at 180x with a 5mm Vixen LV Wideangle. As Io's shadow cleared the planet at transit's end, Ken watched in the Mak-newt while I followed in the 4" Fluorite. We slewed over to Saturn, where the 6" revealed Cassini's division with ease, subtle banding on the planet , and an unevenness in the "A" ring at Encke's Minima.

Turning from the planets, we revisited a few doubles (and the lovely i Cass triple) as our night vision slowly returned. By this time it was about 1AM, and the browsers and testers had left us alone, so we closed up shop to walk about the field. One visit was to Bruce Sayre, a fellow Californian and member of the SVAS. By daylight we had been impressed with Bruce's new 12.5" all-aluminum binocular scope, and hoped he would share a view through it. He patiently showed us how to manipulate the various clever adjustments for interocular distance and focus, and pointed the scope at M27. The nebula and its wispy extensions seemed to stand out from the starry background, and the central star glowed brightly, apparently suspended in front of the whole apparition. We slewed the scope to M13, M57, and M15, and were rewarded each time with amazing, apparently 3D images. The globulars appeared to me like comets viewed head on, the bright cores charging out of the field toward me and trailing countless stars behind! Bruce's scope(s) tracked easily at about 150x, and his careful construction and design made the sometimes tricky binocular adjustments easy as the three of us shared the scope. A very impressive instrument!

After walking about for a while we headed over to where Bill and Mark Cherrington had set up their 25" f5 homemade dob. Longtime members of the SFAA and regulars at the Texas and Oregon Star Parties, this father and son team are known as experienced deep-sky observers and we were curious to see what they'd be viewing in their giant scope. As we walked up Bill was stooped over the 80mm Jaegers finder mounted on the mirror box, while Mark perched about 6 feet up the ladder, at the eyepiece as the scope pointed near the zenith. They were hunting NGC6905, the Blue Flash nebula, which I found upon ascending the ladder is indeed blue and lumpily annular in appearance. They were happy to share the view, and after all had taken a turn at the eyepiece with the Blue Flash we moved on to galaxies in Pegasus. First up was NGC7479, a barred-type spiral, the bar being very bright and dominating the appearance in the 25". On second glance the wispy, delicate spiral arms became visible.

Mark said something about how the sky had gone bad, and I looked up in disbelief at the thousands of stars overhead. To my suburbanized eyes it still looked like stargazing paradise! Yet upon more critical inspection the sky did appear grayer than earlier in the evening, and I recalled that when we were over at Bruce's we had felt a sudden warming that had led me to open my coat and take off my gloves. A wave of warmer, wetter air must have moved in around 1AM and reduced the limiting magnitude to a "mere" 6.3 or so. We pressed on with our big-scope tour regardless, while Mark told tales of how perfectly black the sky had been Wednesday, the night before we arrived (he and Bill had been on site since Tuesday, along with several others in the hard-core contingent.) We visited NGC7331 and Stephan's Quintet, spotting the "sixth" galaxy in that group some arcminutes off to the side. Then another barred spiral inside the Great Square, the catalog number of which I can't remember, but it was smaller and less impressive than 7479. Then on to M74 in Pisces, and the Seyfert galaxy M77 in Cetus. This latter appeared as a tightly wound spiral with many arms, and at high power the bright core was clearly nonstellar. Near M77 we stumbled across 2 moderately bright (with 25"!) NGC galaxies, their identities now forgotten, though I will have to find them again beacause one had a striking dust lane. At my request we swung over to NGC891, the bright, lane-crossed edge-on in Perseus, before slewing over to the Veil.

At about 300x with an 0-3 filter in the 25" under steady skies, the detail visible was almost beyond description. Fine fingers and tendrils wound through the section opposite 52 Cygni, and so many stars were resolved that I was reminded of the old theory that the nebula was actually composed of unresolved stars. Viewing with enough aperture, it's easy to see how earlier students of the Veil were fooled, as several chains of faint stars do appear to parallel the tendrils of nebulosity, the same way chains of naked eye stars stand out against the Milky Way.

In all we spent almost 2 hours with the Cherringtons, and I thought I could detect the zodiacal light brightening in the East as Ken & I headed back to our campsite at around 3AM. Before turning in I had to have one last look at the Veil, so I screwed my O-3 filter into a 30mm Ultrascopic and slipped it into the Short Tube 80. The entire nebula complex was visible, like a ghostly, broken wheel, an image that still revolved in my head as I drifted off to sleep in the growing twilight.

Saturday night was probably the darkest night of our three at Indian Trail Spring - I've already related the magnitude test I did that night. Yet after our session with the 25", it was almost anticlimactic. We set up the f6.5 VX102 ED refractor with a 2" diagonal, and got great wide field views of the Double Cluster, the Veil (can't get enough!), Barnard's Galaxy, and M24 among others. And we had more nice views of Saturn and Jupiter through the Mak-Newt. But as word of Orion's presence at the event spread with each night, we had more and more visitors, and spent more time standing next to the scopes and answering questions than looking through them. And we were looking forward to packing up the next day and a long drive home, so again we turned in fairly early. I am already looking forward to returning, perhaps on my own rather than under the Orion banner, so I'll be able to devote more time to star-hopping under the velvety Eastern Oregon skies.