by Albert Highe
| Scope | 17.5" f/4.5 ultralight |
|---|---|
| Eyepieces | mostly 9mm Nagler, then 14mm Radian. |
Friday afternoon, I drove out to Michelle's Plettstone observing site in the Sierra Foothills. Michelle is a generous host and has a wonderful location. Thank you, Michelle.
Five of us set up for a night of observing. During the late afternoon, some high thin clouds moved in. However, by 10:00PM, they dissipated, leaving excellent, dark skies. The temperature was pleasant - in the mid-60's. The relative humidity never got much above 50%. There was no wind. Initially seeing and transparency were very good.
This was first light for my 17.5" at a dark sky location. I started out observing bright Messier objects that I've seen many times with many scopes at various locations. I also had observed a number of these just a couple of days before at Montebello with the 17.5". M13 and M5 were highly resolved and breathtaking at 222X with my wide field 9mm Nagler. As expected, they didn't appear much different than at Montebello. However, M104, the Sombrero Galaxy, showed up much better than at Montebello or with my 12.5" f/5 from dark sky locations. The thin extensions were longer and the dust lane was more prominent. The most striking difference was the size and brightness of the dimmer portion of the galaxy south of the dust lane.
I haven't observed M83 in years. It is low in the sky and views of it never interested me much in the past. However, I decided to point the scope at it since it was well placed. I was pleasantly surprised. With the good conditions and the large aperture, I could clearly see a large barred spiral. The central bar was long and narrow, extending across about a ¼ of the f.o.v. With averted vision I could also see the two most prominent spirals, trailing from the ends of the bar and sweeping out almost a complete circle.
I then began my more serious work of searching out numerous faint fuzzies. One of the highlights of the night was searching for the galaxies in Abell Cluster 3574, which is just a couple of degrees east of M83. The new Uranometria has an enlarged chart of this area on page A18. The Field Guide indicates that there are 31 galaxies in this cluster within a 1°-diameter circle, although only 13 are plotted. The 10th brightest galaxy is mag 13.4. I found the following eight galaxies the first night:
IC4329 (mag 11.3, 3.4'X1.9') The largest and brightest of the group. I could see this moderately bright oval with direct vision. It brightens noticeably toward the center.
IC4329A (13.0, 1.4'X0.4') Looks like a smaller version of above, and just 3' E.
IC4327 (13.9, 1.1'X0.5') Faint oval, almost along same line as above two galaxies. I think this the most difficult listed member in the cluster. Nearby star interferes with view, but I could hold this oval with averted vision about 80% of the time.
NGC5291 (14.1, 1.2'X0.8') Could hold with averted vision. Appears irregular on SW edge.
MCG-5-33-5 (15.1, 0.4'X0.3) Known as the "Seashell Galaxy". This is the irregularity on the SW edge of NGC5291, above. This is the faintest "name" galaxy that I've seen. I can hold it with averted vision at least 50% of the time.
The following galaxies make a nice triangle, and are similar size and shape. I could hold all with averted vision.
At this time, shortly after 11PM, seeing began to soften, especially low in the south where I was observing. Stars were bloated at 222X, making small, faint galaxies invisible or indistinguishable from faint stars. I abandoned my search for members of Abell 3574.
I reduced my working magnification to143X with my 14mm Radian and moved to other areas of the sky, observing mostly less challenging objects. Stars were somewhat bloated, but tolerable. I packed up and went to sleep (in a real bed!) at 2:30AM.
Two more observers arrived Saturday afternoon. It was cooler than on Friday and breezy all day. However, the wind dropped to near zero at sunset. The temperature, in the mid-50's, was about 10 degrees cooler than Friday night, but still rather pleasant. The relative humidity was generally lower, only approaching 50% after midnight.
| Scope | 17.5" f/4.5 |
|---|---|
| Eyepieces | began with 9mm Nagler, then switched to14mm Radian. |
Like on Friday, seeing and transparency started out good. I began observing at 222X using my 9mm Nagler. As I returned to Abell Cluster 3574, it was apparent that transparency was noticeably better than on Friday. All of the galaxies mentioned above were easier to see, and I galaxy-hopped across the 1° field at 222X. I could hold even the faintest members with averted vision most of the time. I also detected other galaxies not plotted in Uranometria. I quickly found the remaining members listed in Uranometria.
I was interested in comparing views of a couple of galaxy clusters that I discovered while at Fiddletown and reported on last month. Page 72 (blow up on page A10) in Uranometria shows a clump of galaxies in Coma Berenices. I expected better views with the new 17.5" vs. the 12.5" I used last month. Initially, the views were very good. But after a few minutes, the faintest galaxies began to fade before my eyes. Suddenly, the views were about the same as I had seen in my 12.5". Plettstone is darker than Fiddletown and I was using quite a bit more aperture. However, the seeing and transparency at Fiddletown last month was excellent and the seeing and transparency at Plettstone had just deteriorated.
I took a look at M51. The spiral structure was bright and easy with direct vision. I've only seen this structure with averted vision with my 12.5" from the best skies. So aperture does matter. But the transparency wasn't the best I've experienced. The "bridge" of material between M51 and its companion NGC5195 could not be seen. Yet, I've seen this low contrast detail at Dinosaur Point with my 12.5" when the transparency is excellent.
I continued observing the remainder of the night with my 14mm Radian at 143X, reacquainting myself with many of the Messier objects. Most were considerably different with the larger aperture.
The view of M97, the Owl Nebula, was notable. It was the brightest I had ever seen it. I could also detect the "eyes" with averted vision. I also particularly enjoyed NGC6603, within the star cloud M24, in Sagittarius. It stood out clearly in this star-rich region, its fainter stars more densely packed than its surroundings.
I turned in early at 1:30AM.