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Lessons From Polyphemus

Andrew Pierce

[Editors Note: This article is part of a continuing series about members' experience with SJAA loaner telescopes. Have you borrowed one of the fine telescopes from the SJAA library? Share your experience in an article for the Ephemeris.]

They gather by night in the darkest of places, manipulating their black shrouded cylinders, speaking a language the uninitiated cannot understand. If you have been to a star party you probably seen them. These Druidic figures are the Big Dob Guys1.

By the fall of 2000, I had been involved in amateur astronomy for about two years and was curious whether I had what it takes to join this exalted group. My first serious scope was an ETX Astro, the original model, without any electronics. (If you don't think the 90 mm Mak-Cass is a serious scope, I invite you to compare it with images from the department store refractor that resides in a dusty corner of my garage.) After less than a year I graduated to a 9.25-inch Schmidt-Cassegrain, a very competent all-purpose telescope. But I don't have the eyes of a Freeman or an O'Meara who can see profound detail at middling apertures so I wanted to know - did I have what it takes to be a Big Dob Guy?

I knew I was in no rush to add a monstrous new scope to my life without some practical experience. A lot of thought and research went into buying the 9.25 inch scope and I'm grateful with every use that I took the time to study all the options. Before I could think about adding a true light bucket to my garage I wanted to try one out. The SJAA loaner scope program was just the thing.

A quick glance at the Ephemeris revealed that the largest scope on tap was a 14.5 inch truss-tube Dobsonian - a scope any true priest or priestess of the exalted rites would be proud to collimate.

I e-mailed Mike Koop with my request. He wanted to know one thing - how big was my car? When I replied that I had a station wagon, he suggested I drive up to Fremont Peak that Saturday night because Bob Havner was bringing the scope up there. I had been to the Pinnacles, Lick Observatory, the Trinity Alps and Molokai with a telescope but I had never been to the historic astronomy site and local party zone at Fremont Peak. This could not be missed.

Driving to Fremont Peak is a little like driving in Rome or Chicago - you should not be allowed to drive up there unless you have driven there at least twice before. With the help of the wrong map I ended up in foggy Salinas where a local helpfully directed me up Crazy Horse to the San Juan Grade which I followed all the way to San Juan Bautista without seeing the sign for Fremont Peak. After circling the mountain twice, I knew where it was, but I still had no idea of how to get there. I finally found my way to the top three hours after leaving Palo Alto.

It was worth it. I found Bob Havner by stumbling around in the dark until I saw a Big Dob that had a "loaner scope" look. Loaner scopes do not come with ceremonial plaques, custom shrouds or digital setting circles. Bob let me push the scope around a little bit, my first real experience with a Dobsonian. My observing notes read simply: "I could enjoy this."

After a few minutes I let Bob have his last outing with scope. It was September 30, 2000, a night when Fremont Peak was at its best, with virtually no light pollution penetrating from the foggy lowlands. There was a large enthusiastic crowd. In fact, if you are reading the Ephemeris there is a pretty good chance you were there. I particularly remember, very late at night looking through Jane Houston Jones' big scope at M38 and the nearby NGC 2158 cluster.

A week later on October 6, 2000, I picked up the loaner scope from Bob Havner at Houge Park. It was beautifully collimated from the start, an experience that did not always recur. Bob left me with the scope and soon a line of fifteen kids and parents queued up to look at the moon on this partly cloudy evening.

Bringing the scope home was like bringing home a puppy. It made a mess in my house and garage and took far more time than I could have imagined. It wouldn't fit into the garage without bending. However, I soon found I could assemble it and disassemble it, collimate it and even look through the eyepiece without a ladder. I also grew to admire the elegant simplicity of the Dobsonian design, which is all about homage to the biggest practical mirror.

Bob Havner warned me it was not a very good planetary scope and I found that it did not produce optimal planetary images compared to the 9.25 SCT or a 6 inch Mak-Cass. However, my notes remind me that at various times I was able to split the Double Double in Lyra cleanly, see the Cassini division and see detail on Jupiter beyond the obvious bands, including the Great Red Spot. Still, for any one thinking of borrowing this scope it is not trivial to collimate, it does not always hold its collimation, and it performs best on galaxies and nebule and less well on star clusters, double stars, and planets.

So what did I learn from the monstrous Cyclopean beast? First and foremost I learned what aperture can do. I got my first look at such objects as the Intergalactic Wanderer, NGC 2419, in Lynx; Hubble's Variable Nebula, NGC 2261; the Flame Nebula, NGC 2024; and Thor's Helmet in Canis Major, NGC 2359. The planetary nebula M27 took on a whole new shape, with bilateral extensions that are perpendicular to the familiar hourglass shape. I was also able to get spectacular wide field views of galaxy groupings and saw details of galactic structure that gave the faint fuzzies distinctive personalities.

I also learned that one is less likely to use a telescope if it is difficult to put together and requires a large vehicle to move. The big dob could fit in a mid-size hatchback by nesting the mirror box inside the rocker box and placing the mirror and upper ring in the back seat, but this is not recommended. I did not get the scope out to dark site locations as often as I thought I would and on several occasions opted to bring the 9.25 inch Schmidt Cassegrain simply because it assembled more easily and can be disassembled and packed in less than five minutes. The 14.5 inch loaner scope does not have clamps or captive hardware. It takes about 45 minutes to assemble and collimate if you do not have help.

I also learned that if you go by yourself to a dark site with a 14.5 inch scope and want some help you can count on the kindness of strangers. One night at Fremont Peak there was only one other amateur astronomer because the park rangers had run off the friend who was supposed to meet me. Brian, a total stranger was glad to help, even as his wife yawned in their car. Once set up, I spotted a milky looking cluster near M35. After showing it to Brian, I realized it was the same object, NGC 2158, that Jane Houston Jones had shown me two months earlier at the same site. And so the torch was passed.

On another night at Montebello, I had a similar experience, although the person who helped me assemble and collimate, an experienced amateur telescope maker, commented that I had the "world's most dysfunctional Dob." This was a little unfair. The scope is obviously a homemade project, but it does what it's supposed to do. Since it's a giant clumsy one-eyed beast, I took to calling it Polyphemus.

I also learned that a large aperture can do amazing things even in the suburbs. Towards the end of my period with the scope I couldn't get out to tour Virgo and Coma Berenices due to bad luck, bad weather, and other distractions. The final Saturday night that I had the scope I was not in a position to go to a dark site but it was an unusually dark fine night in my yard in Palo Alto. I was able to traverse Markarian's chain and several other galaxy trails in Virgo and Coma, picking up no fewer than eight new-to-me galaxies with the scope set up only 10 feet from my front door. I also got a nice surprise on my last night with the scope, as a combination of good collination and good seeing gave me a memorable view of M3, after I had given up on getting super sharp views of clusters with this telescope.

So am I a big Dob guy now? Well, not yet, but next summer, if you see someone fussing over one of Tom Noe's 14.5 inch Dobs, muttering something about Abell clusters or optimal thermal performance, it just might be this alumnus of the SJAA loaner program.

1Many Big Dob Guys are female, but as a group, like Refractor Guys, I can't help but thinking of them as "Guys."

Mail to: Andrew Pierce
Copyright © 2001 San Jose Astronomical Association
Last updated: July 19, 2007

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