High-Quality Small Refractors

Fisher Middle School 1997 June 13

At the public star party held by The Astronomy Connection (TAC) at Fisher Middle School, Los Gatos, California, on 13 June, 1997, telescope-owners outnumbered guests by some twenty to one, likely because it was the first weekend of summer vacation. Fisher is about as good as suburban sites come, but seeing that deteriorated as the evening wore on, and a first-quarter Moon, conspired to make observing challenging.

Lots of high-quality small refractors were present. Two of our members had brought their new Vixen 102 mm f/9 fluorites, just delivered from Telescope and Binocular Center. As I have previously reported, they are both pleased with these instruments. I got to star-test one of the fluorites, on Vega at 184x, and it appeared to have optics on a par with my own mid-1980s vintage Vixen 90 mm fluorite, which was set up a few meters away. Both instruments exhibited out-of-focus diffraction patterns identical the same distance inside and outside focus, with just a hint of color (purple and green) in the out-of-focus views. Neither telescope shows any in-focus color even on (say) the Moon.

An observer with a Pronto was chasing down Messier objects. (see below) At 30x we found several, including M17 (the Swan or Omega Nebula) and M51 (the Whirlpool Nebula). We could also see NGC 5195, the fainter companion to M51.

We all spent a lot of time looking at the Moon. At 202x in the Vixen 90 mm, I could see portions of the Fresnel Rilles, and that part of the Hadley Rille that lies directly south of Hadley crater. I could not see Hadley Rille where it trended north/south past the Apollo 15 landing site, though. The shadow of Plato's eastern wall was withdrawing across the crater as the evening wore on. I looked several times for craterlets in Plato, but did not see any with certainty.

An apparition of the Hesiodus Sunrise Ray was to take place later in the evening, after Moon set from our longitude. Nevertheless, we watched the terminator cross Pitatus, and saw bits and pieces of the rim of Hesiodus start to become illuminated. One such bright spot was directly across the crater from the gap in the Pitatus/Hesiodus common wall through which the ray emanates; it may have been the start of the ray.

I spent a little while observing the Moon with the Intes monocentric eyepieces that I have reported on previously. While working near the terminator, I could position the telescope so that the objectionable ghost image of the illuminated portion of the Moon lay entirely upon the dark part. In this condition, the improvment in contrast that the monocentrics provided over other eyepiece types, was quite noticeable.

We narrowly missed a partial occultation of Io by Ganymede. We had simply forgotten about it, and when one of us noticed that two of the Galilean satellites were nearly superimposed, it took only a few minutes to notice for sure that they were drawing apart.

-- Jay Freeman

I was intrigued by the recent discussion s.a.a about what can and cannot be seen with small refractors. What better way to judge the discussion than by observing for myself?! I was not surprised to verify that Jay's side of the discussion was correct. I was easily able to find all the Messier objects that I tried for (except for M51, which Akkana found). The open clusters (M6, M7, M23) looked fine, better in some respects than in my 12" Meade LX200 SCT since I can achieve a very much wider field of view with the little Pronto. Globulars (M4, M5, M22, M28, M80) looked like little fuzz balls with a steep brightness gradient. Only in M22 was I able to resolve any individual stars. (I didn't try for M13 because it was near the zenith where my "mount" does very poorly.) M57 (the Ring Nebula) was easily resolved as a ring. M8 was big and bright clearly showing some structure. M17 looked nice. M20 was there but I can't really claim to have seen the "Mercedes emblem". M51 was very difficult. I could clearly see it after Akkana found it but I could not see the companion (NGC 5195). (Jay and Akkana did see the companion, however.)

The bottom line is that I found 12 out of 12 Messier objects that I tried for in the middle of a huge city with a quarter Moon in just a few minutes of trying. I have no doubt that with more time I could have seen dozens more with little effort. The truth is that small refractors really do work. -- Bill Arnett

Jay Reynolds Freeman / Bill Arnett); last updated: 1997 June 14