Observing at ASSNE's March meeting

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Observing at ASSNE's March meeting

Unread post by Pete » Mon Mar 15, 2004 9:26 pm

13 Mar 04

Today wasn’t particularly promising for observing – very windy with night temperatures forecast to fall into the teens. But Mark was planning on observing after our ASSNE meeting so I set up the 12” scope in the meeting hall’s back field around 6:45.

The meeting ended around 7:45, but before going out I pulled on a couple of sweaters and donned my insulated one-piece work suit.

This scope is technically complex, and even after using it for 2 years I still occasionally blow the alignment procedure. This was one of those nights. The GPS did set itself for Rehoboth, and I did remember to change it over from polar to azimuth mode. But on the first attempt, where Paul was running the scope for me, the scope wanted to align on Capella and Alkaid. When it slewed very close to Alkaid (on the end of the big dipper’s handle) I screwed up and had Paul center on Mizar (the double star next up the handle). Surprisingly the computer accepted Mizar, but when I slewed to M42 I was looking at the leftmost star in Orion’s belt – about the same height above M42 as Mizar is above Alkaid. It took me 2 more failed attempts before I figured out what I was doing wrong. On the 4th (and successful) alignment I used the 12mm illuminated reticule and got a really accurate fix on Capella and Alkaid. And the scope ran dead nuts on for the rest of the night, centering every object.

The sky is beautiful tonight. There’s no moon. The wind has disappeared and the seeing and transparency are good to excellent. And we have 6 or 7 scopes plus Bob’s “thin man” binoculars in the field.

The first target was M42, observed at 97X with the Orion Ultrablock filter. M42 was getting a bit low in the west, but it wasn’t so far down as to have much of an adverse impact on viewing. Most of the folks who took a look had just been observing the Orion Nebula through another scope, so the improved contrast from this filter knocked their socks off.

M81 & M82 were the next target of the evening. They both just about fit into the Nagler 31’s fov. Both are big and bright at 97X, but I can’t make out any detail.

M44 (the Beehive cluster) is one of my favorite open clusters. Everyone that was present got to slew the scope around and enjoy this grouping at 97X.

One of Jupiter’s moons was casting a shadow on the north main equatorial band, so we slewed to Jup and observed at 179X. The shadow was very easy to see. Since we had half a dozen people sharing the scope at that point and since I hadn’t checked on Jupiter’s moons using my computer I didn’t really look for anything else.

Bruce has his 10” on M65 and M66 in Leo, fitting both galaxies into the same fov. So we put the 12” with the Nagler 31 on Leo to compare against the fov he was getting with the new Antares 52mm 2” eyepiece that Matt had just purchased from Mark. The view seemed to be the same, so we brought the Antares 52 over and put it into the 12” for a more direct comparison. The field looked about the same to me – both galaxies fit comfortably into the center 2/3 of both eyepieces. For the money, the Antares is a fantastic eyepiece. I couldn’t see the minor pincushion distortion out at the extreme edge of field that Matt was talking about, but I was bothered by the “kidney bean” distortion usually associated with the first generation Nagler eyepieces.

Tonight’s observing objective was to take the S&T March ’04 tour of Puppis. So here we go.

M46 is a very nice rich open cluster of stars, most of them being 11th magnitude, but a few 9th mag or even better. As Matt looked he spotted the next target – NGC 2439

NGC 2439 (a tiny planetary nebula nested within M46. That’s pretty remarkable at 91X. We pumped the magnification up. But 254X was overdoing it. This 11 mag planetary is only 1 minute in diameter, so is easy to see, abet tiny.

M47 is another open cluster about ½° in diameter, with several double stars. Matt called out attention to a yellow/blue double that stood out from the blue stars in the rest of the cluster. 97X

NGC2423 (at 97X) is a small less than spectacular open cluster in this tight grouping of clusters.

Mel 71 had us puzzled. Later research revealed that Melotte Listing is an obscure catalog of open clusters. I couldn’t figure out how to guide the GPS to the listed coordinates so we passed on this one.

NGC2440 is a relatively large (17’ dia.) 9.4 mag planetary nebula. We were able to view it at 97X but its pretty dim. And this completes the short S&T tour of Puppis.

M105 It’s getting colder now, and most of the club members have departed the field for warmer locations. But M105 (38 million light years distant) hosts one of my favorite tight galaxy groups. At 97X, M105 is easily visible - as is NGC 3384.

In the attached web download M105 is the bright elliptical at left.

NGC 3384 is below and right of center. NGC 3384 (the galaxy in the upper right) is always very difficult to see, and can only be observed in very dark skies. I’ve seen it from Barrington and from Westport once or twice using the 10”. Matt thinks he sees it. And maybe I do and maybe I don’t.

It’s now around 10:30, and I’m feeling the cold through my insulated boots and heavy wool socks. For the evening’s finale, we go to M3.

M3 vies with M13 as the best of the northern hemisphere globular clusters. And it’s up! One of the nice things about our ever-changing sky scene. At 179X the 3 of us remaining at the scope enjoy busting into the core of this magnificent glob.

And then I shut ‘er down and start packing.

I drift over to check out Bob’s homebuilt binocular mount. Bob is demonstrating it to Rose. And I get to play with it, observing M44. It works wonderfully. Much more easy to control than my tank mirror setup. But we’ve come to expect nothing less from Bob and his endeavors.

Unwilling to leave the field while Bruce is still set up, I duck into the museum to find Bruce, Matt and Mark discussing camping at some dark site this summer – something that Bernie and Dave had brought up at the meeting. Oh joy. A great night observing. And something to look forward to.

Pete Peterson


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