Sunday, May 17, 2009

Kitt Peak Star-B-Que!

About twice a year, the Tucson Amateur Astronomy Association (TAAA) schedules an afternoon cookout and evening's observing for members at Kitt Peak National Observatory's (KPNO) picnic area. Located about a 55 mile drive southwest of Tucson, and located at about 6500 feet elevation, it is an excellent choice for an event like this. The skies are great, and with the pavilion and scattered picnic tables in the area, it can't be beat. The TAAA has been running events here for over a dozen years or so, and even when the weather is bad, it is still a nice place to go to escape the desert heat for some camaraderie and a pot-luck meal.

Folks started arriving shortly before 4pm when the mountaintop closed to the public (the picnic area is about 1.5 miles down the road from the peak). The gas grill was started as members set up their telescopes for the night's observing. With moonrise at about 1am, and permission to stay even later, it looked to be a great night of observing. Some daytime scattered clouds were not an issue, though the horizons were very hazy. By 6pm, the scopes were ready and most members were stuffed by the food. Highlights for me was the guacamole Verne made table-side, and the home-made potato salad by Donna and Mike. We brought brownies from a mix that were also well received.

The highlight of this evening was perhaps the opportunity to observe the sunset through the world's largest solar telescope. The McMath-Pierce Telescope has a 60" diameter mirror that focuses an 80cm (30") image of the sun onto a screen. About 30 of us gathered there at 6:30 for the tour and observing session organized by Clyde Plymate, a TAAA member who works for the National Solar Observatory . The 3-mirror system was analogous to a Newtonian telescope, Clyde informed us - the long focal length resulting in a large image size about 3X brighter than ambient sunlight, rather than a focused spot that would catch something ablaze. Sunglasses were convenient to use to dim the image slightly, but the unfiltered image wasn't too uncomfortably bright. Unfortunately, though there was some plage activity as well as granulation visible, there were no sunspots - solar activity remains low even though we're well past the minimum stage of the cycle.

At one point, a jet was seen transiting the image - likely somewhere over California or near the west coast, it took about 20 seconds to traverse the solar image. As the plane exited the edge of the solar image, the hot exhaust gasses trailing it also dragged some of the light from the sun's disk - a really cool effect!

As time passed, the white, circular image of the sun became oblate and reddened as it approached the horizon. Eventually the horizon was spotted rising into the tracked solar image and cut off the disk. Interestingly, even though the horizon was perhaps 100 miles or more away, the tiny silhouettes of saguaro cacti could be seen in profile on the sun's disk - it really was an amazing sight - thanks Clyde!

Shortly we all returned to the picnic area, our telescopes and the quiet murmur of the astronomers as comments were passed along and calls were made to share views. I had my 14" Celestron set up for visual use (no photography early on, at least), and a highlight for me was when I installed a binoviewer (a prism arrangement to allow both eyes to view the image) I obtained almost a year ago, to view Saturn, it's edge-on rings and 4 or 5 moons that were visible. You had to battle collimation and focus issues, but when properly adjusted, it was quite breathtaking. Many of the old favorites were enjoyed by all - The great globular cluster M13 was observed in Hercules to acclaim, but then compared to the 4X bigger globular Omega Centauri just clear of the southern Horizon, most were left just speechless! Spring is galaxy season, and favorites from M81 and M82 near Ursa Major to NGC 4565 (Needle galaxy in Coma Bernices) and NGC 5128 (Centaurus A radio galaxy) were shared.

Eventually the crowd thinned, and I got out the camera and tripod, hoping to catch some "star party action". Unbeknownst to them, I imaged Michael and Mary Turner (60s w/28mm F/2.8 lens ISO 800) working on their observing list of star clusters, Mary at the star charts, while Michael moved from over her shoulder to telescope. What made the picture interesting was the constellation of Scorpius rising over them and some of the star clouds of the Summer Milky Way (still invisible naked eye) making their appearance. After that, I mounted the camera (Canon XSi) with a zoom lens piggyback onto the C-14, using it as a tracking platform to follow the stars. Even with the haze and scattered clouds near the southern horizon, I chose to shoot one of my favorite areas near Antares in Scorpius. It is full of globular clusters, both reflection (starlight reflecting off gas clouds), emission nebulae (gas clouds excited to emission from UV light from nearby stars) and dark clouds, seen in silhouette against the Milky Way. The result is a "quick and dirty" straight average of 30 minutes (10X3m each) of exposure with the camera and zoom lens set to F/3.2 and about 120mm focal length. It calls for more exposure, but it looks nice for a short effort!

The crowd continued to decline, finally, Michael and Mary left, then Donna and Mike left as we finished packing up the scope. Still before moonrise, we made it to Tucson an hour later, the moon by then revealing a multitude of high, thin clouds.

Dark of the moon and an earlier-rising Milky Way call for attention this coming weekend, but we're headed to California for the Memorial Day weekend Riverside Telescope Makers Conference up in Big Bear, my 22nd. Melinda has never been to California, so should be a fun time for us both!

1 comment:

David A. Harvey said...

Wow Dean! Some very nice shots here - I especially like the Rho Ophi region! One of my favorite targets. I waiting for some "engineering time" on the 90" to attempt a similar shot.