Loitering in M24

by Jane Smith

Of my 3 nights at GSSP, Friday was by far the most fruitful. I decided to do Bumpass for my final night, although I had my reservations about sky quality. After all, it was Friday the 13th! Fortunately, the astro-gods came through. Conditions were a near perfect mag 7 with glorious 9+/10 seeing, and very high transparency. Wind was absent and temperatures hoovered at a balmy 50 degrees, unusually warm considering the parking lot's 8,300' elevation.

Earlier that afternoon Steve Gottlieb had graced the GSSP crowd with a stimulating lecture on deep-sky observing. Steve had somehow managed to collaspe his 40 years of observing into a mere 2 hours. Truly miraculous! At one point he mentioned the gems to be found in M24, the Sagittarius Star Cloud. My ears perked up and I suddenly found myself eager to venture to the southern skies in search of M24 et al.

I have since learned that many sources incorrectly list M24 as NGC6603, a small open cluster contained in the star cloud, however this is incorrect. Messier's notes clearly indicate he was referring to the entire star cloud, not just the cluster.

I arrived at Bumpass about 7:30pm after caravaning from Lost Creek with a train of 10-12 other vehicles. I setup between the esteemed Director Ozer and Joe-Bob Jardine, always great company. The lot filled quickly and I spent the next hour taping up tail lights on the cars of some members of the public who wanted to hang around for a look through the telescopes. I finished just as it was getting dark. I started the evening by paying my respects Jupiter. Then I'd be off in search of some of M24's treasures.

Jupiter is always a treat. Plus it's an easy target for me to determine just how good the seeing is. The planet was rock solid when I upped magnification with my 7mm, so I knew seeing was very good. The north and south equatorial belts were quite prominent and very colorful in orange to brown. At one point I thought saw glimpses of the Great Red Spot when seeing came in well. I heard someone say there would be an occultation or transit of one of the moons later in the evening, but I didn't remember to look.

After oggling the great gas giant for several minutes I pulled out my trusty Sky Atlas 2000 and turned to page 22 for directions to the cluster. However, when I glanced in the EP I felt a bit silly. One doesn't need to consult a chart to find NGC6603. All they need to do is look in the EP!!! Located in the southeastern quadrant of the cloud, the cluster immediately pops out. It's clearly the most concentrated parts of the star cloud. WHEW... and what a star cloud it is! I stood for several minutes just taking in the grandeur... the sheer size of it and the richness of that part of the sky. Without a doubt, this is one of the prettiest regions of the Milky Way.

I then turned my attention to the cluster. At 80X it was smaller than I had expected, but still extremely bright. There appeared to be a bright elongated area that ran vertically through the central portion. This puzzled me and prompted me to take a closer look. I popped in the 9mm Nagler. At 150X the cluster was somewhat clearer, and it was now evident that the vertical bright area was a line of stars running down the center of the cluster. However, it was still not well resolved. So in went the 7mm Nagler. At 185X the cluster looked better, but I figured if I was to get a better look I'd need more aperture. I immediately thought Lord Alsing and made a mental note to pay him a visit later.

Next was Barnard 92 and 93. These two dark nebulae looked like a set of huge black "lungs" hanging in the sky. They are situated near the center of the star cloud. They appear somewhat oval in shape with B92 on the right being more "stout" than B93. Barnard nebulae have always fascinated me: the Ink Spot(B86), B68 in OPH, and someday I'll see the Coal Sack in the SoHem.

Next I started looking for a little trumpet-shaped asterism Paul Alsing had told me of earlier in the evening. He said it had been designated "Jen's Confluence", after Jennifer Polakis, IIRC. It was located down and to the right of B92. I searched for quite a while, but couldn't find it in the fabulously rich star field. So, I figured it was a good time to visit the Alsing-Wicks encampment at the far end of the parking lot.

I first asked Paul if we could take a look at NGC6603 in his 25". As always Lord Alsing most graciously obliged. We were there in a flash. Sheesh.... how I wish I knew my way around the sky like Paul! I was surprised to see that the cluster didn't appear that much more resolved in a 22" than it did my 10". Perhaps because I was at higher magnification? I wish I had asked Paul to put in a higher powered EP. This is something I need to try when I finish the 16".... to see what affect aperture has on resolution. Certainly resolution improves with more aperture, but is there a point at which resolution is limited, no matter what size mirror you have?

After we looked at NGC6603 I asked Paul for directions to Jen's Confluence. What a fun little asterism! Once I knew it's location it was easy to see in my 10". The final object I wanted to find was NGC 6567, a planetary nebula almost directly south of Jen's Confluence. This one stumped me. I'll give it another try next new moon. I also want to give Markarian 38 a try, a much smaller open cluster west of 6603. It wasn't listed on my chart, so I expect it may be a SGNB.

The rest of the evening I spent cruising eye candy and hunting down Barnard's Galaxy with Richard Ozer. This is a tough object because of it's low surface brightness. We spent a fair amount of time making sure we were in the right location, but it paid off. We were both able to see the galaxy easily. I looked more like a haze than a galaxy, but it was a neat feeling to know we were looking at a member of our Local Group. Great fun.

I packed it in at 3am and headed back down the mountain. All in all, an excellent and memorable night.