In its original form, this article was published in the RASC Kingston Centre's newsletter, Regulus, under the title My First Six Months With a 17.5" Dobsonian. It described my experiences as a first-time user of a large aperture scope. Since the NYAA was very much connected with this scope (see details after the story), I decided to re-print the article here, along with an epilogue detailing more recent developments in this continuing saga...

THE STORY

On Friday, January 27, 1989 my observing horizons were expanded greatly, and a dream was finally realized. This was the day I purchased a used (or should I say previously enjoyed?) Coulter 17.5" Dobsonian. No longer would I have to use my averted vision to the limit in order to detect more deep sky objects. No longer would I have to dream about better, brighter views of the more familiar deep sky objects. Now all my observing wants would be fulfilled. Of course, with such progress there are some new problems created too. As I have found in using other large telescopes, there is an initial adjustment period during which you make a number of discoveries about the new instrument and how it works (or doesn't work!). The following are some of my discoveries the good and the not so good along with some observations made during my first six months with the new scope.

"The 17" (as I call it) is a large red tube 20" in diameter and 74" in length which rests on a 27.5" square rocker box. The tube assembly weighs 140 pounds, the box 90 pounds, and the mirror 29 pounds. The 17 weighs in at a hefty 259 pounds total. The focuser is of the 1.25" variety and there is no finderscope (I use the hex bolt at the top end of the tube!). The entire telescope was mounted on three wheels by the previous owner and this allows the scope to be moved around on smooth, level surfaces by only one person. Unfortunately, such surfaces rarely occur in nature, so this is not of any use in the field. This was my first discovery about the 17: without such a surface, it becomes a two person telescope.

Initially, I took the 17 back home to Oshawa so it would be close at hand, and so I could roll it in and out of the garage and up and down the driveway as required, totally unassisted. Strangely enough, although it looks gigantic indoors, once it is rolled outside it looks rather small!

The f/4.5 focal ratio gives a focal length of 2000mm -- the same as my C8. The quality of the images in the 17 is not bad in spite of some of the stories I've heard about similar scopes.

The skies the first night home were clear until about 23:30. I rolled the 17 half way down the driveway. Within an hour the mirror and scope had equalized thermally with their surroundings. Despite the light pollution (Oshawa has a population of 150,000), those first views were still very good! M42/3 was strikingly blue green in colour with abundant mottling clearly visible. Detail was also visible in M82 and M81 both of which were brighter and more extensive than in my C8. M44 in Cancer showed several colourful binaries. Sirius, quite simply, should be left until after your deep sky observing is finished!

I used the 17 on a total of three nights in Oshawa. By this time the initial excitement was beginning to wear off and I longed to unleash its full potential under a dark sky. So on April 8, with a clear Saturday night looking imminent (how about that for a change!) and with Doug Clapp and Randy Hendriks going out to observe (they could help me move the 17) I decided to take the scope to the family farm 25 km north east of Belleville. I also took along my C8 in order to facilitate direct comparison of the performance of the two scopes.

Although Orion was sinking in the west, the Zeta Orionis Nebula was easily visible in the 17 but only barely in the C8. M42/3 were even more beautiful with the dark sky than they had been in Oshawa. Many objects seen in the 17 were eye popping to say the least. It was like starting the hobby all over again! In Leo, M65 and 66 were great. M65 was noticeably larger than M66 which appeared to have "wings" running off it (spiral arms!). All of the detail in M65 and 66 was especially impressive since both of them were visible in the same field of view. A dust lane could be seen in nearby NGC 3628 and the supernova in M66 was just visible. NGC 2371 in Gemini showed some mottling.

Just as nebulae and galaxies were breathtakingly transformed by the 17, so were the globular clusters. To say that M13 was a knock out is an understatement! My views of M13 were the most incredible I have ever had. Nicely resolved, each individual in this incredible blizzard of stars stood out plainly with direct vision. It was like looking at a Palomar photograph. M92 was very good, again showing lots of well resolved stars, and M5 in Serpens was excellent.

When looking at the brighter globulars in the 17 I got the feeling that if I cranked up the magnification a little, it would be possible to see through them! M22 was well resolved and gave the impression of having a "sheet" of stars draped in front of a more distant and condensed core - an interesting effect. I finished the night going through Sagittarius and Scorpius and being similarly amazed by the views afforded by the 17. One in particular, the Trifid Nebula, was outstanding with the trisection jumping out at me. It was a very exciting night.

Throughout all of this observing, I slowly acquired a feel for how to use this telescope. Having used the 13.1" Coulter, I initially thought that the 17 would be as easy to use. While this is largely true (if you'll pardon the expression), the sheer size and weight of the 17 make it somewhat harder to handle. For one thing, you can't put your arms around it and push (unless you have very long arms!). Neither can you push as hard if you're standing on a ladder! And, as it turns out, the scope is a wee bit tipsy in certain orientations with the three-wheel setup. Fortunately this is only a problem near the zenith. By using a sturdy ladder and gripping diametrically opposite sides of the top of the tube, the 17 can be muscled around. A better way still is to have someone on the ground do the steering. Of course the latter only works when you're not alone.

I could go on and on about the wonders opened up to me by the 17 but I'll wrap it up with just a couple more. On the Canada Day (1989) weekend I had the 17 out again with Paul Markov (who helped me move it!). M110 was astonishing in its extent and naturally M31 was amazing (as I was expecting by then!). But my most recent big thrill came when I checked out NGC 7331 in Pegasus. Immediately next to it were four galaxies, three of them easily visible. If you compare the charts for NGC 7331 in SkyAtlas and Uranometria you will get an idea of the difference between the universe as seen by an 8" scope and that seen by a 17" an exciting difference!

So what is to become of my C8? It will continue in active service for many years to come. I have yet to exhaust its photographic potential, and it is better suited for lunar, solar, and planetary observation. This is an interesting situation: the merits of the 8 and 17 are mutually exclusive! Therefore, just as Leslie Peltier divided his time equally between his 6" and 12" scopes, I will divide mine evenly between the 8 and the 17. At least until I can get a 36"...

EPILOGUE

Incredibly, it has now been almost 4 years since I purchased the 17 from an NYAA member in, of all places, Cobourg. I would like to thank the NYAA for NOT buying this telescope!

During its three month stay in Oshawa, the 17 eclipsed Mike Sherba's 16" as the largest telescope in Oshawa. Tony Ward reports that this corresponds exactly to a strange period of humility and quiescence on Mike's part!

After spending a year dominating the living room of the family farmhouse, the 17 was moved into a 9'x11' Sears garden shed about half a kilometre to the south in February 1990. A few months later I added a 10'x10' matrix of patio stones in front of the shed. To use the 17 I simply unlock the shed and roll out the 17 onto the patio, all by myself!

I have since added a TelRad and a Celestron 6x30mm finder (just like the one on my C8!) to make finding objects easier. The current focuser, while adequate, becomes difficult to adjust at sub zero (Celsius) temperatures. Eventually I plan to add a 2" focuser, or at least a better 1.25" focuser.

From this story it may appear that I have succumbed to aperture fever. Well, I have, I'm loving it, and I am beyond cure! But what about the optical and mechanical quality of this scope? Much ado has been made about these topics recently. Mechanically, the azimuthal pivoting action is rather stiff which makes for some difficulty near the zenith (as I mentioned earlier). I plan to install a BKD (Bill Kelly Device) by next spring (finally!). Other than this, I have been quite happy with the mechanics of this scope. Optically it looks OK to me (except for planetary viewing, which I don't use it for anyway), especially when TeleVues are used instead of my own crappy eyepieces!

While The 17 continues to thrill me with its deep sky views, I use it now mainly for variable star observation. In this department, it has allowed me to follow my variables through minimum without breaking a sweat: stars at magnitude 13.5 stick out like a sore thumb! This takes getting used to, since it's just like seeing constellations from a dark sky instead of a light polluted one. I have been able to do several "inner sanctum" estimates (13.8 or fainter) thanks to the awesome light gathering power. The faintest star I have seen so far (that I have a listed magnitude for) with the 17 is 15.2 (not much better than my C8). However, I anticipate seeing 16.0 or fainter once I get the 17 housed in an observatory where I can get truly dark-adapted! But that's a story for another time (and one which will have your head spinning)...

So how would I sum up the large aperture Dobsonian experience? I think Caesar would have said it best: Veni, vicidobsonus, vidi -- "I came, I got a large aperture Dobsonian, I saw!"