I brought my 6-inch f/5 and 80mm f/15 refractors, dual alt-az mounted. I have not had either scope to a dark sky, and I wanted to see what things looked like in both. The 6-inch had a wonderfully large 3.25 degree TFOV at 25x with a 31mm Nagler. I could fit many objects in a single field, and even smaller ones had a wider context in which to frame them. What helped even more was a DioptRx, which I purchased recently after discovering large exit pupils expose astigmatism in my observing eye. The DioptRx miraculously sharpens the stars and saves the view. The 80mm really surprised me: of course I could not resolve as many stars, but the contrast in the view was very good, and it seemed to show dark nebula even darker than the 6-inch--perhaps as a result of a smaller exit pupil and a dimmer sky background. I compared the views in the scopes often, and was amazed that the 80mm kept up with the 6-inch. IC 342 as an example -- I could see the small brighter core in both scopes, though I could see more of the halo with 6-inch. It seemed to me I could see "deeper" with the f/15 than I could with an 80mm f/4 finder -- I could see more galaxies and so on. I wonder what it is about long focal lengths which might make such a difference.
As night fell the one day old moon set, and I was able to watch it through both scopes (but mainly through the 80mm) as it set behind trees on a hill. As a bracket for the night, in the early morning I observed M31, the Andromeda Galaxy, and then the Double Cluster, rise on the eastern hill. It was fun to see stars in the DC wink in and out behind branches and twigs of the trees. Seeing these objects with earth in the same FOV puts them on my own human scale -- it makes them seem very large, yet somehow close.
As darkness deepened I tried for Antares, GNT 1 -- which I was able to get in the 80mm @ 133x with a 9mm orthoscopic -- an airy disk with tremulous diffraction rings, but the very faint B star was steady within the diffraction ring; current separation is 3.2" and its PA is to the west, which matched what I saw. A star is a bright orange, B is light green but faint. I've tried for GNT 1 many times these last few years, this is my first positive observation.
16H 29M 24.47S -26° 25' 55.0" P.A. 277.4 SEP 2.56 MAG 0.96,5.40 SP M1 DIST. 169.78 PC (553.82 L.Y.)
C/2017 T2 (PANSTARRS): I had the presence of mind to print a finder for this 8th mag comet before leaving the house. It seemed to be fairly close to the large galaxy M106 and I was pretty impressed with myself to find M106 with just a Telrad find. Sure enough there was a large elongated diffuse glow, brighter at one end, which at first I thought might be a galaxy. I made a sketch of it in the surrounding star field (with the 6-inch at 25x it was in the same field as M106). I came back to it a couple hours later, and sure enough the comet had moved slightly. There was no response to the comet filter. The elongation was the beginnings of the tail, which I noticed more prominently the second observation (probably due to good dark adaptation. The view through the 80mm rivaled the 6-inch, just a few less stars and half the field of view.
For most of the evening I simply scanned about aimlessly, but enjoying the views. In the 6-inch the Veil Nebula, both east and west, just barely fit the same field. All of Kemble's Cascade and into NGC 1502. Sulafat to Sheliak with M57 in the middle. Dark nebula beyond count. Dim and bright globular clusters, small and large spreads of open clusters. It was hard for me to take notes on what I was seeing: with such star fields I could only think of the general beauty of the scenes rather than the specific nature of what was seen.
The sight of the night was B 168 / Cr 470 / IC 5146 the "Cocoon Nebula." In the 6-inch I could see the entire extent of these objects. B 168 looked like a trench dug in the star field, with stars falling into the dark mark made. The cluster was a scattering of faint stars, and the nebula seen when using the H-Beta filter as a weak fog in the northern quadrant of the cluster.
Using a UHC filter I explored some unfamiliar HII regions in northwestern Cygnus. DWB 145-148: faint wishbone shaped nebula, about 1 degree long and half a degree wide at the end of the fork orientation NE-SW. DWB 129: a large lazy "S" curve seeming to sprout from an 8th magnitude star and flow to the SW, with a chain of four stars following the central western edge. DWB 165 was a large oval cloud, with a bright star on its north central rim. I find only one reference in SIMBAD, the discovery paper "The Cygnus X Region, V. Catalogue and distances of optically visible H II regions" published in 1969 by H.R. Dinkel, H.J. Wendker, and J.H. Bieritz (DWB). They were measuring distances to H II regions to see if they could be ionized by Cygnus X, and whether a "Ring of Nebula" formed about 10 degrees around Gamma Cygni was ionized by this star (their findings were inconclusive).
I ended the night with views of Mars, Saturn, and Jupiter through the 80mm. I tried the "straight through" viewing method, with no diagonal used, the eyepiece mounted to the focuser. Also a Televue planetary filter, at 92x. Mars was swimming a bit in seeing, it was still low, but I had glimpses of a snowy pole and some dark areas on the orange red disk. Saturn looked really great, with bands on the planet and Cassini's Division plain on the multi-colored rings. Jupiter showed multiple bands and what I thought was the GRS with a turbulent oval eddy behind it, but checking today it seems there are two large storm systems imitating the GRS. I had dim impressions of a couple large festoons, but only barely.
No comments:
Post a Comment