Tuesday, August 27, 2002

Backyard fun 8/27/02

I've had the 14.5" f/5.6 Dob set up in my Los Gatos backyard, uncovered, for the past few nights. I finally went out last night about nine o'clock for a few hours of observing. Well, actually, a friend phoned just as I was walking out to put my eye to the eyepiece. So, it was initially more yacking than observing.

The seeing began decently, although the sky looked rather bright. I will do some star counts in the future to know about what the limiting mag is, but I estimate about mag 3.5 last night. Of course the 10x70 finder helps a great deal under such conditions. In fact, I used the (RA) finder extensively during the night. The eyepieces I used were a 20 Nagler and 12 Nagler, both type II. I thoroughly enjoy these eyepieces... they yield 103x and 172x respectively. The only other equipment used was a Telrad, Volume 2 of the Night Sky Observers Guide (NSOG), older Tirion SA 2000 and older Uranometria 2000.

Cygnus was nicely placed and I began with NGC 6811. This is a nice open cluster just off the "wing-tip" of Cygnus' western arm. Start from mag 2.9 delta Cygni and move past mag 5.1 SAO 48718, past mag 6.25 SAO 48697 and a bit further to an obvious cluster. This is a nice cluster of medium density in an oval or even with some imagination a triangular pattern encircling an area devoid of stars. A nice bright group of about 10 stars sat just at the western edge of my 48 arc-minute field of view. The contrast between the cluster and bright stars so close-by make this a fun visit.

Moving back from Delta Cygni toward Gamma a bit over 4 1/2 degrees I hunted down NGC 6811. It sits just north of an imaginary line between the two bright stars. I also use the stars 32 and 31 Cygni (the later a nice double) to "point" toward the intersection with the line between Delta and Gamma. Worked great! Those of you using The Sky should note that the position appears mismarked. Look at it and you'll find a rather sparse grouping of stars designated at 6811, but look just to the north and you'll find what I believe is really the open cluster. NGC 6811 is a nice open, rich in the center with some haze off to the east side of its densest part, then showing some "wings" extending out to the east and west. There seemed to be more dim haze to the northeast of center as well and possibly another dim arm off to the south.

NGC 6871 was next, lying close to Eta Cygni. I used Gamma to draw a line to Eta, helping establish some scale that I could translate to the Tirion charts. This open cluster sits south-southwest of and very close to the mag 5.4 star 27 Cygni, which appears to be part of the cluster. This is a big, bright and sparse open cluster... appearing to me as a large splash of chains of stars in a line curving in a line north to south. There are about 6 bright members of the group overlaying many dimmer members. I noted what I thought was more of the cluster separated to the east, more bright stars, but dimmer than the members of the western portion. I also found myself marveling at the description of this cluster in the Night Sky Observers Guide! It was amazing in its detail... so precise, what a piece of writing! I can think of only one person that gets such detail.... initials SG. Look at this cluster and read the description. I'm sure you'll be as amazed as I was.

I looked around in the NSOG for other targets in Cygnus. I was quite surprised to find Biurakan 1, another open cluster, listed at 3 stars (relatively easy). Looking at the coordinates I thought they looked familiar... right next to NGC 6871! Heck, it was still in the eyepiece. It was then that I realized Biurakan 1 was the other dimmer cluster of stars east of NGC 6871. The cluster was sparse, just a handful of bright stars with the brightest in the center of the western edge. There were many dim stars in an arc running north to south and arcing slightly back to the east. I also felt there might be another "branch" of the cluster to the west, but it was very dim.

I finished the night looking for NGC 6874. By this time the seeing had deteriorated significantly, and I had to keep adjusting focus and felt I just could not get sharp stars. I could not find this object on the Tirion charts. So I looked at Uranometria. Not there either. What was this about? I spent several minutes checking and rechecking the RA and Dec and going back to the charts, but it really was not there. I then read the NSOG, which called it non-existent. I could not find it. NSOG does claim it is there, and even notes it as more conspicuous than Basel 6. In fact, I thought Basel 6 might have been NGC 6874, and shared locations! But no, I got skunked. However, I did hunt down Dolidze 39 - a hazy open cluster comprised of dim stars north to south about 10 minutes long with a turn on the south end toward the east. A bright seim-circle of four to five stras arced to the north.... this was a very small grouping of stars within Dol 39. Again, it found myself being somewhat confused at what I was looking at... maybe this small knot of stars (the semi-circle) was part of IC 4996. Was it? I now think so.

It was almost 11 p.m. No moon yet, but the seeing was crappy. So, I decided to tear down. Eyepiece in case, books under my arm, I walked the 25 feet to my back door. What a great way to observe!

When I awoke today I found it very windy in Los Gatos. So windy my bino-mount blew over in the afternoon. I now think the bad seeing around 10:30 last night was the very start of the wind picking up, maybe just a shift in direction causing turbulence. It was obvious when it happened. But, I sure had a good time. For the first hour I was looking through the eyepiece while yacking on the phone, not easy to do. The second hour I was well dark adapted and having a wonderful time, enjoying being out in my backyard (t-shirt and sandals, btw!).

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