D-Files and Amateur Telescope Making

 

 

Future Astronomer's First Encounter
with a Big Telescope

Jack Eastman, DAS Chief Observer

Mt_Wilson_60inchDavid Nakamoto’s latest article in the LAAS Bulletin brought back some fond memories of my own first encounter with the 60-inch and Mt. Wilson in general. Rewind the Earth in its orbit about 47-billion kilometers, I was in, or just out of high school, enjoying a wonderful night at Mt. Wilson’s 6-inch refractor.  

The Earth was about 6.6-billion km farther back when my father and I were in the parking lot of the old Mt. Wilson hotel with my newly acquired 40mm Polarex (equivalent to the Unitron model 127) refractor.

A gentleman came up and wanted a look, and of course I tried to show him a few objects. He then asked if we would like to look through “one of ours”. Wow, sure!

So we went up to this little dome near the 60-foot solar tower and fired up a “really big” 6-inch refractor. The man’s name was Joe Hickox, then the resident Solar Observer at Mt. Wilson. We looked at the Moon, Saturn and several star clusters and double stars. Joe asked me if I’d like to point the telescope at something, of course I said, “YES!” Just as I loosened the clamps, it sounded like someone poured a bunch of ball bearing balls down a stove pipe. Panic! Yes, it got our attention.

What happened was the weight on the driving clock had reached bottom and
triggered the rewind motor.  Whew!, no harm no foul, but it did wake my dad and me up! Getting to know Joe, and his sense of humor, I think he knew the rewind was about to kick in just as I loosened the clamp, and scare hell out of us. It worked. And so it was, my introduction to Mt. Wilson, the 6-inch telescope. And a lifelong friendship with Joe Hickox.

 As time went on, we were able to visit Mt. Wilson often and have the use of that wonderful 6-inch, which brings me to that night, mentioned above. (A photo of that 6-inch refractor appears in The Birth of Stars and Planets by Bally and Reipurth, fig 2.1, p 17)

O.K., fast forward those 6.6E9 kilometers. Several of us from the Los Angeles Astronomical Society, our high school astronomy club and friends were using the 6-inch. It was getting late and we were thinking of hitting the sack, when there was a knock on the door. It was Tommy Cragg, another Mt. Wilson solar observer, LAAS member and ace variable star observer. We asked us if we would like to come over and look through the 60-inch reflector. Would we?! You betcha! So we hoofed it over to the 60-inch which was pointed at Saturn. Saturn was low in the South which made for interesting gymnastics getting to the Cassegrain focus. We climbed onto the observer’s platform, then onto the telescope itself, straddling the lower tube casting like it was a seriously overweight horse.

Once we were in place, with a free hand we were handed a huge eyepiece, with rods sticking out of it so it couldn’t be dropped through the opening onto the mirror. (Considered really bad form!)  Leaning forward, we found the image and moved about in an attempt to get better focus. What I saw was a huge elliptical blob of light, looking much like an illuminated football in a dark swimming pool. Maybe a couple of darkish spots (between the ring and the ball) but really a disappointing view. Well, it was the Cassegrain focus, and at this early stage in my existence, the few Cassegrain telescopes I’d seen werent much good. Well, the problem was (as you might have guessed by now) the seeing. It seems Dr. Dinsmore Alter (then Director of the Griffith Observatory) had the telescope for his research looking for evidence of Lunar outgassing and temporary local atmospheric phenomena. This required near perfect seeing, as his method was to take the highest resolution photographs possible in infrared and violet light, looking for possible differences in detail between the two wavelengths. Well, the seeing that night was so awful that after one look, he gave up and went back to bed. The telescope was set up and running and Tom remembered us over at the 6-inch, hence the invite. The seeing didn’t seem to be all that bad at the 6-inch, and it looked O.K. in the 4-inch finder on the 60.

There’s a lesson here: Large telescopes are much more affected by seeing than small ones—a lesson often taught out here at Chamberlin where small ‘scopes out on the lawn seem to outperform the 20-inch Clark. Since that experience I’ve looked through the 60-inch many more times before my escape to Colorado. The telescope is good and the seeing that night was clearly the culprit.

In the following years I have had the privilege of looking through and playing with larger telescopes than that venerable 60. I’ve beaten Mt. Wilson, twice, by a single, solitary inch. I had had several close encounters with the 61-inch Lunar and Planetary telescope at Mt. Lemmon in Arizona, and finally a couple of us had the ‘scope for an entire night. R.B. Minton had the telescope, mainly for photographic work on Jupiter and confirmation of his discovery of the reddish polar caps of Io. When he was done with his photographic run, we stuffed in an eyepiece and hunted down all the objects we could think of. David Nakamoto’s observation that all the show objects we know and love are, indeed, too big for the field of such a large ‘scope is definitely true, but looking into the cores of globular clusters like M-13 M-92 and the like was pretty spectacular. The Mt. Lemmon ‘scope was set up as a Cassegrain at f/13.5, their 75mm eyepiece giving 275X with a field of view of only 0.12 degrees. Still, it was great fun to play with such a large (to us) telescope. 61-inch #2 was the Astrometric Reflector of the U..S. Naval Observatory at Flagstaff, Arizona.  This one, designed for accurate positional measurements, is long focus (F/10) mirror, folded in half with a large flat secondary. The operator set it on M-57, the ring nebula. I was amazed that the central star wasn’t visible, as it had been at Mt. Lemmon. The operator said to punch the guide motion, and lo, the star flashed into view from behind the crosshair in the eyepiece. The telescope settings were so accurate that the star was hidden by those crosshairs!

It was quite a thrill to actually look through these instruments, at the time some of the largest around. This certainly helped cement my lifelong love for astronomy, and science in general. I can only hope some youngster might have a similar experience and be guided into a career in the sciences. 

Photo of Mt. Wilson 60-inch Telescope courtesy Wally Pacholka, AstroPics.com/TWAN

>>> Back to D-Files


The Denver Astronomical Society
DAS Home Page