Tuesday, July 27, 2010

Thunder Ridge Star Party ~ Observing Report

During my trip to Colorado, I once again attended the Thunder Ridge Star Party (TRSP) hosted by my friend Phil Good.  The TRSP-IV was held July 9 - 11 at Phil's ranch property, at approximately 9000' overlooking Eleven Mile State Park.  The location is excellent for a star party given its elevation, clear southern horizon, and weather.  While storms often roll through in the summer afternoons and evenings, the skies often clear quickly after sunset.  Some of us who attended TRSP-III last year, are also aware of the kindred native spirits that frequent the ridge...

Which of these Bison is different?
...The area was a fruitful hunting ground for our ancestors, and evidence remains today on Thunder Ridge.  A walk around the ridge will reveal signs of circles where ancient fires burned within teepees.  Careful hunting will reward one with fragments of worked stone and an occasional arrowhead.  During TRSP-III, several of us had left our tripods and/or scopes set up from one night to the next.  During the intervening afternoon, a very strong, rogue gust of wind lifted every piece of equipment and threw them several feet.  Miraculously, nothing was damaged...not a mount, not a scope, not even Phil's brand new TEC 180mm Flourite refractor, "Uncle Milt," sitting atop its mount.  Clearly, the ancients were amateur astronomers and made sure to protect our gear.

This year, the skies were quite good on Friday night.  By dark, I would estimate the seeing at 4/5 with occasional moments of 4.5/5.  The transparency was near perfect, and while just a guess, I would estimate that the NELM at zenith was approximately 7.  Frank Nadell (I think) had a sky quality meter and perhaps he can chime in with a more accurate figure.  I had brought along my TEC-140 APO on my DM-6, as well as many charts and a lengthy observing list.  I observed many objects over two nights, and below I'll overview the highlights.

First up was Pluto.  I had observed all the planets except Pluto, when the International Astronomical Union (IAU) stepped in and demoted Pluto to the status of "Dwarf Planet."  How this happened and why makes for interesting reading, and Universe Today sums it up nicely.  Despite the arrogance of the IAU, I was still intent on seeing the little guy.  To be honest, I was not sure that I would be able to pull it in with the 140mm of aperture, but I was bound and determined to give it the old college try.  Circumstances during the TRSP were just right for a serious run at this faint speck, not only due to the dark skies but also due to the fact that Pluto was passing Barnard 92, a dark nebula.  This would make its identification much simpler in that there were no stars to confuse it with, even though it is passing through the heart of the milky way in Sagittarius.  To the left is the star chart from the July Sky and Telescope that I used to locate the star field and hunt for the object Pluto, formerly known as a planet.  I inserted a 5mm Pentax XW (196X) and began to look for Pluto.  After about 10 minutes I glimpsed a faint speck with averted vision.  I looked away and looked back and there it was again.  It was very difficult to hold in my sight, and I realized that the best way to confirm what I was seeing was to get a look through Franks 12 inch Dob.  A few minutes later (and after getting my brain over the up-down reversal of the image in the dob) and I had confirmed that the tiny speck was indeed there!  Back at the TEC 140 and little Pluto was still extremely difficult to hold in view.  At a visual magnitude of 14, this was quite a catch in the TEC 140!  Pluto was approximately 30.88 AU distant, which equates to about 257 light minutes!

After the hard work observing Pluto, I was ready for some easier targets.  I inserted a 20mm Nagler (49X) and headed over to NGC 6514, the Trifid Nebula, M20.  The view was dramatic.  Not only were the dust lanes obvious, but the definition on the edges of the lanes was jaw dropping.  There was a definite structure to the lanes...I had never seen the nebula as well.  Indeed, even the blue reflection nebulosity alongside the Trifid  (to the right in the image) was clearly visible in the eyepiece.  This was quite a treat and a testament to the skies.

At this point, I had not even considered my observing list, so I spent the rest of the first evening observing many of the other famous Messier objects in the summer sky such as globular clusters M13 and M22, The Swan Nebula (M17), and the great Andromeda Galaxy, M31.  I observed at least a dozen other globular clusters in and around the Sagittarius teapot that I found simply by panning the scope around.  The wide-field views were so breathtaking that I was not concerned with getting out the atlas to identify the objects.

I was beginning to get sleepy but decided that since I had visited Pluto earlier (and Saturn before it set), I should finish up the other outer planets that were now in the sky...namely Uranus, Neptune and Jupiter.  The seeing was deteriorating and Jupiter was difficult at high power.  We were treated to a view of a moon transit, although I do not recall which moon it was.  At about 2:30 AM it was time to hit the sack.

Day two dawned bright and clear and after a good brunch in nearby Hartsel, we (Ian, my niece Cierra, and I) joined Frank and his son Henry on a day trip to find some good bouldering near the 11 mile reservoir.  We had fun scrambling around, eating ice cream, and taking in the views before heading back to Phil's famous "surf-n-turf" BBQ and a second night of observing.

The weather was not shaping up to be as good as the previous night with heavy cloud cover blanketing the area throughout dinner...yet, as often happens at Thunder Ridge, the skies completely cleared within an hour after sunset.  Despite seeing conditions that were just average, I still had an observing list of deep sky objects that I wanted to make some headway on.  Fortunately, deep sky targets do not suffer from atmospheric turbulence at the level of planets or close double stars.  Faint fuzzy objects, remain faint fuzzy objects in most conditions.  I had compiled a list of objects from Sue French's columns in the June and July issues of Sky and Telescope magazine.  She is an excellent observer and her columns are chock full of information and observing ideas.  In fact, they are my favorite feature of the magazine.  Following are highlights from my notes from night two:

NGC 6210 - The Turtle Nebula in Hercules.  At 3600 light years this planetary nebula is a smooth elliptical shaped nebula with an extremely faint halo.

NGC 6400 - Open cluster in Scorpius.  An approximately 9th magnitude cluster with many faint stars ranging from magnitude 10 to 12.  A little lost in the background.  Distance of 3100 light years.

NGC 6441 - Globular cluster in Scorpius.  This one looks familiar as I  visited it last night!  It sits alongside the golden star G Scorpii.  It is small and difficult to resolve but makes an attractive pairing with 'G'.  Interestingly, this is one of only four known globular clusters that houses a planetary nebula...and no, I did not see the planetary!

NGC 6302 - The Bug Nebula in Scorpius.  Sometimes called the butterfly nebula.  This is a small planetary nebula sporting a fairly bright core with extensions that are faint yet quite long.  Distance is 2000 light years.

NGC 6281 - Open cluster in Scorpius.  Best at low power, this is a run of the mill open cluster.  Better looking in the finder scope!

NGC 6569 & NGC 6558- Globular Clusters in Sagittarius.  At 49X (20mm Nagler), these clusters fit in the same field of view in the TEC 140.   Surrounded by many stars, these clusters appear to float in the froth of the milk shake, I mean milky way...just seeing if you are still paying attention!  Both of these clusters can be partially resolved at high power.

NGC 6624 - Globular Cluster in Sagittarius.  Very nice at both low and high power.  At low power there is a long chain of about 12 magnitude 10 stars that form a line running right into the clusters northern side.  At high power the cluster displays a bright condensed nucleus and is partially resolved.

NGC 6652 - Globular Cluster in Sagittarius.  This cluster is parked about 1 degree from M69 and shares the low power field of view.  It is a nice paring and a fitting way to end the second night!

Darren and Burton
All in all, this was the best TRSP I have attended- not only was the observing first rate, but the company was as well!  I got to see some old friends like Jim and Jeannette, Frank and Henry, and Benton, but I made some new ones like Scott, Rebekah and Aaron; Patricia; and Darren and and his dad Burton who drove from Canada.  For those of you who don't know, my trip to Colorado each year is a father-son trip that I do with Ian, and it was great to see Darren and his dad on a father-son trip.  I hope that when Ian is in his 40's he still wants to travel with me.  As always, Phil is the ultimate host...it would not happen without him...who knows maybe I'll have a report on TRSP-V next July...
Scott, Benton, Darren
Phil, Patricia, and...Darren!

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