"TJ": Bob and Cathy's 20-inch Telescope, the history of an almost 30 year old Dobsonian

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Last touched 2016 October 20

This page attempts to document the history and evolution of a 20-inch telescope that is nearing 30 years of age. The telescope has seen a couple of different owners, lived in three different parts of the US and been rebuilt into a different physical form three times.

Image of TJ2, Bob's 20-inch Telescope

| A homemade Crayford focuser | | Quick Disconnect Wheel Barrow Handles | | A Simple 12 Volt Power System |

"TJ" is a 20-inch f/6.4 dobsonian telescope. The current version of TJ (version 2.1) was completed by Bob Bunge in 1999 and updated in the fall/winter of 2001. It is pretty much a Kriege/Berry clone with a few exceptions that will be touched on later.

TJ got it's entry into the world as a United Lens pyrex blank ordered by Marshal Holman of Lillian, Alabama in 1983. I helped Marshal grind the back of the blank flat while stationed in Pensacola, FL in the Navy in 1983. Marshal finished the mirror into a classic, sonotube dobsonian in 1984. I was blessed to be at Marshal's home during first light.

In 1986, a group of Columbus, Ohio amateurs banded together and purchased the scope from Marshal. We rebuilt the scope into a half wood/half truss tube dobsonian in 1987. This version of the scope traveled to Astrofest where it won an award for a computer pointing system installed on it by group member Bill Burton. It also traveled to Stellafane in 1987 where John Dobson himself commented on its longer-then-normal focal ratio. The scope was stored at Warren Rupp Observatory for several years and used from time to time.

In 1991, group members Tom Burns of Perkins Observatory and Jay Elkes of the Columbus Astronomical Society gifted me their shares of the telescope as a college graduation present. I call the scope "TJ" in their honor. From 1991 to 1993, the scope was in storage after moving to Maryland. In early 1993, changes were made that allowed the scope to be set up by a single person.

In 1993/94 I refigured the mirror in my basement. I used 12, 8 and 4-inch subdiameter laps to reduce rolled edge problems and worked back towards a parabola. When classic foucault testing in my basement proved difficult because of air currents, I star tested the mirror on Polaris in the scope. I did a number of figuring sessions with the mirror in the scope using an 8-inch lap and finished up in the late spring of 1994.

I received the mirror back from the coaters in July, with first light for the new TJ being the night Comet Shoemaker/Levy 9 impacted Jupiter. I was left speechless by the detail I could see in the D and G impact spots and was completely pleased by the performance of the mirror.

In the coming years, TJ traveled to many, many observing sessions at Crockett Park, near Catlet, VA, then a prime observing site for the Northern Virginia Astronomy Club. TJ also made trips to Starfest (1996) in Canada, Hidden Hollow, back at it's old Ohio stomping grounds, Winter Star Party (1997) and several times to the nearby Delmarva Stargaze, also a normal observing site. At Crockett Park, in 1996, I helped more than 300 people look at the core of Comet Hyakutake in the span of about four hours with TJ. Another memorable observation was of Mars at WSP in 1997. The seeing conditions were sub-arcsecond and the detail was terrific. Even nearby AP refractorheads were impressed. At third memory moment were the vivid reds and greens seen in the nucleus of comet Hale-Bopp from Skyline Drive in Shenandoah National Park.

Throughout this time, longer trips with TJ in our Jeep were limited by lack of space to bring along our two Golden Retrievers, Lady and Tramp. TJ weighed in at about 350 lbs and took up most of the room in the Jeep. So in 1999, I started a long-awaited rebuilding of the scope into a modern Kriege/Obsession style telescope that would at least halve the weight and reduce the volume of space TJ took up it the Jeep.

Construction of TJ2 went fast and smooth, with first light being in the fall of 1999 with first "Dark Light" being at the 1999 NOVAC Star Party at Crockett. The original 1-inch OD struts used on TJ2 proved not to be up to the task, so in 2000, I rebuilt the scope with larger, more stable strut poles (1 5/8-inch OD). TJ2 has also been to Delmarva and in 2001 traveled via Autotrain to the Winter Star Party. In the spring of 2001, TJ2 had changes made to it's focus cage and other minor improvements. New light for this configuration of TJ2 (TJ2.1 :-) was with the Greenbelt Astronomy Club's 2001 Astronomy Day show. More minor improvements have fine tuned the scope some more since then. TJ2 is equipped with a Sky Commander Digital Setting Circle system. A small table attaches to the rocker box that can hold a laptop running Megastar that is interfaced with the Sky Commander.

In November and December of 2001, I added a simple 12-volt power system to TJ2 to power the laptop computer, the secondary mirror and eyepiece dew heaters, as well as to supply power to the Sky Commander for cold weather operations. I've detailed this system on a separate web page. In June, 2002, I built a shelf to hold a 72 amp/hr Marine Deep Cycle battery. The shelf is made from 1/4-inch luan plywood and slips onto the front of the rocker box, between the wheels.

During 2003, I laid some patio stones in the backyard to support TJ for a season of Mars observing. While observing Mars one night, I got curious and made a 17-inch aperture stop. I knew that this would have the affect of removing a rolled down edge that the mirror suffers from (this is a major advantage of making your own mirror... you understand it's weaknesses). This turns TJ into a 17-inch f/7.8 newtonian! The planetary images greatly improved. From April through October, I made more than 40 drawings of Mars, most with TJ. In August, 2003, the Washington Post ran an article about amateur astronomers watching Mars that featured TJ and a drawing made through it. Similar drawings were made during the 2005 season.

In 2004, I figured out how to stuff TJ into the back of a 1998 Saturn SW2 wagon. This saved load up time compared to the Minivan I had been using and provided more flexibility. Additional work included tweaking the design of the wheel barrow handle quick disconnect. In 2005, the Saturn was exchanged for a Ford Escort Wagon. I loaded the scope up once in this car before realizing I could shave additional load up time by trimming two inches off the end of the wheel barrow handles, allowing them to stay on during transport.

After several years of more use then anything else, in 2006, TJ finally got some TLC. This was kicked off when after record dry weather in late March, the truss blocks on the mirror box dried out so much the poles would not fit in them. After being sanded out, it was realized there wasn't a tight screw/bolt on the mirror box and for that matter most of the telescope. After that, the large parts of the scope were disassembled and cleaned with light soap and water. The mirror box and rocker were cleaned out from all the dirt and grass that had found their way in during the 2005 Mars season. The formica surfaces were also brushed with soap, water and cleaned.

The biggest part of the project was a rebuilding of the supports for the wheel barrow handles. Wood pegs were replaced with steel and aluminum since over the years, the wood pieces had broken a couple of times and were generally in bad shape even though made from oak. First light and test for this was Astronomy Day, 2006 at Goddard Space Flight Center. Prior to going to the Almost Heaven Star Party, additional tweaks were made to the secondary dew heater system. Solder joints from the spider vanes to the heater cord on the secondary had proven over the years to break or come loose under regular transport conditions. Holes were drilled and 4/40 threads to were tapped in the vanes behind the secondary mirror shallow to provide secure and tight electrical contacts.

I like to use TJ to observe Mars from my urban backyard. Under dark skies, I've been tracking down and drawing all of the Arp Peculiar Galaxy Clusters. My favorite dark sky site is Spruce Knob, a West Virginia mountaintop that is a 4 hour drive from home.

After setting up TJ at the 2009 (fall) Tuckahoe Star Party, things started to go south quickly. At certain points in altitude motion, there were "bumps" as you moved the scope. The digital setting circles didn't hold lock at all... and objects weren't were often several fields of view away from where the DSC/computer said they were.

I actually wasn't too surprised there were problems. I had been using TJ regularly for a couple of years, yet providing little or no TLC; with family and work life I was lucky just to get any observing time, let alone much time for the telescope's upkeep. Yet, there was another reason as well; I had honed TJ into a mean observing machine. There wasn't much reason to tweak anything as I finished off observing all 338 Arp objects and started in on the Herschel 400 list.

Upon arrival back home, for the first time in several years, a good inspection of the scope was had. The most impressive discovery was that after 22 years of abuse and wear and tear from gravity, the glue and nails holding the bottom board of the mirror box had started to fail and the bottom had pulled loose by about a half inch. This was large enough so the board was hitting the azimuth encoder. This neatly answered the question as to why the DSC had failed at Tuckahoe. Close inspection showed several of the nails used in 1987 were almost completely rusted through and the glue used was not to be seen. However, more alarming was that every one of the truss blocks made in the 1999 update were cracked and clearly subject to failure. These clamps, made just before the Berry/Kreige book had come out, were made from solid pieces of maple, whereas Dave and Richard recommended layers off glued board instead.

The immediate problem, the mirror box based, was solved by deploying some new glue and using wood screws to hold the board in place. Even though I knew maple to be the wood of choice for the clamp blocks, I decided to experiment with easy to get red oak boards from the local big box hardware store. They glued together well enough; the boring of the 1 5/8th hole went well enough, but almost as soon as I started to attach them to the scope problems arose. First off, when I dropped one, it broke. Another, when on the scope cracked when I purposefully stressed it by pulling on the truss. So a 2nd set of blocks were constructed from poplar wood. These blocks were also slightly thicker.

On November 21st, 2009, I set up TJ at Tuckahoe once again. The scope worked flawlessly. More important, I was able to pick off the last three Arp galaxies, completing a 10 year quest to observe and draw all 338 of these objects. TJ had been used to to see the first and last, compiling a total of 298 objects from ten different locations:

Big Meadows, Shenandoah National Park, VA 12 objects
Camp Highroad, VA 1 object
CM Crockett Park - Catlet, VA 13 objects
Delmarva Star Party, Tuckahoe State Park, MD 47 objects (three events)
Laurel Highlands Star Cruise, Hazelton, WV 17 objects (two nights)
Nanjemoy Observatory, NCEEC, Charles County, MD 5 objects
Sky Line Drive, Shenandoah National Park, VA 9 objects (night of the 2001 leonids!)
Southern Park, Charles County, MD 54 objects (a favorite winter time site)
Tuckahoe State Park, MD 146 objects
Winter Star Party, West Summerland Key, FL 8 objects

The last couple of years of observing this list had added the additional challenge of early morning winter observing since a lack of clear spring evenings forced a change in observing habits.

In January 2009, TJ was featured in this Washington Post article about the NOVAC star party. Photo taken with a low end Casio point and shoot camera sitting in the grass.

As Arp observing started to wind down, I started the Herschel 400 list and also built a list of planetary nebula using Megastar. As of winter, 2011, I have about 100 Herschel objects left, but they are all winter/spring objects.

During the fall of 2011, I built a Crayford focuser for TJ.

In the fall of 2011, I also purchased a 5x10 foot trailer from Colony Cargo. This trailer is light, is long enough to hold the 10 foot ladder and is only 4 feet tall so it rides really well behind a Ford Explorer SUV.

With the trailer acquired, several tweaks were made to TJ to optimize performance for the trailer, with an eye towards reducing set up and tear down time at the observing site. The original battery shelf was showing it's age and starting to fail. It was also not designed to serve as a storage shelf for the heavy battery. A new shelf made from 1/2-inch plywood was constructed and designed not only to hold the battery all the time, but also stay on the shelf when the telescope was moved.

Another tweak was the construction of a larger roster tail shelf. One large enough to hold the computer, the sky commander and a clip board with my drawing supplies. It was also designed to stay on the scope while stored in the trailer. All of this means the scope is now stored partly assembled, and all wiring is kept in place. These two tweaks... the new battery shelf and the new roster tail trims a good 10 to 15 minutes off both set up and tear down time in the field.

Additionally, with almost all observing gear stored in the trailer, I can be off and going in about 15 minutes after deciding to go. This has allowed several sessions that I would have missed in the old days... especially those where I arrive at the site midnight or later in the cold, chasing those spring time objects. I would have never had the energy to reconfigure the SUV or van and spend an hour loading up the scope at 11pm.

By 2011, the coating on TJ's mirror was showing wear. I don't clean the mirror very often. Some dust on the surface rarely impacts performance in the field and cleaning almost always wears the coating and also risks scratches and damage. I once was set up at a star party peacefully observing dim galaxies in a corner of a field, high up on the ladder when two amateurs came over. One of the rudly pointed a white flashlight onto the mirror. Upon seeing a thick coating of dust, said "My god John, come look at this mirror." They then talked briefly how impossible it would be to see anything through this scope before moving on. I don't think they noticed me at all, high above them and they certainly have never seeen the drawing of the 15th magitude galaxy I was making at the time!

So in March of 2012, I attended the 13th session of the Mid Atlantic Mirror Making Seminar held by the Delmarva Stargazers near Smyrna, Delaware. At MMM #13, under the careful eye of expert mirror maker David Groski and with much help from Dr. Bill Hanagan and master Steve Swayze, TJ's mirror was refigured once again. This time, the rolled edge was removed and most of the remaining turned edge reduced.

After the refiguring work, the mirror was chemcially coated with silver. A tight fitting lid was made to go over the mirror and 3M silver anti-tarnish strips placed inside the cover. This has worked well and the coating lasted about a year, but a year with little use.

With some use, I decided I was not happy with the figure of the mirror, so a return to the MMM mirror making seminar was scheduled for 2015. Prior to attending, I constructed a full size lap for the mirror. Plaster was poured on the mirror and backed with plywood. The concept was to use to the full size lap to hog out glass from the center so the rolled and turned edge could be further reduced. While it proved almost impossible to get good contact across all of this lap, large amounts of glass were removed prior to attending the seminar.

At the seminar, Steve Swayze coached me through additional work with the full size lap and then eight and six inch laps. The "inside" rolled edge was elminated and the outer turned edge reduced. Steve's Ross Null test showed a good over all correction, but the mirror currently has some zones and a rougher surface then I would like. Some tests in the driveway, with the uncoated mirror suggested acceptable, if not improved performance was at hand. While the Moon and Jupiter looked great, poor seeing didn't allow for a good star test to be performed.

Nonetheless, in the spring of 2015, I took the dive and drove the mirror to Majestic Coating in New Jersey, where the owner took outstanding care of the mirror. In addition to the primary mirror, the secondary mirror was removed from the OTA and recoated. The coating on this mirror was in far worse shape then I had guessed. With the secondary removed, the OTA got a complete overhaul. All screws and bolts tightened. The dew heater system was moved, as I rarely used it. Most black surfaces got repainted. Ever troublesome bolts on the spider assembly were carefully tightened and locked down with lock-tight. The focuser was better aligned and various little issues fixed.

Upon return of the mirrors, the rest of the scope inspected. An afternoon was spent working on how the base of the scope is stored and secured in the trailer. The secondary mirror sides were repainted and the mirror glued back onto the spider.

Memorial day weekend of 2015, on Saturday afternoon, the scope was set up and the secondary mirror carefully aligned, and the DSC system tested. That evening, and the next evening, we hosted friends and neighbors over for a first light star party, looking at the Moon, Venus, Jupiter, M-5, M-13, M-104 and Saturn. Seeing still did not allow a very good star test, but at 20-inch aperture, planetary performanced appeared similar to it did when I had before stopped the mirror down to 17-inches. Post parties, more tuning was done to the entire system. Electrical issues resolved, some cords repaired, mirror box blocks adjusted and tightened, for example.

In August of 2015, Freddy, our 2007 Ford Explorer, pulled "Tracker" the trailer, carrying TJ to the Almost Heaven Star Party held at The Mountain Institute on Spruce Knob, West Virigina. The location at TMI is one of the darkest locations on the East US Coast. During the first clear night, it became apparent that I was one of only a few folks still observing at 3:30am. Talking around the next day, many folks had been dewed out. I found this interesting since TJ relies on some passive design and some simple technology to remain dew free in even heavy dewing conditions.

Since we had recently acquired some pet lizards, I happened to have a low cost IR temperature sensor with me. So the next morning, I took some readings. I have since written up a piece looking at the data (PDF file) that has since been published in a couple of club newsletters.

Upon return home, it became apparent that "Tracker" the trailor needed some TLC. The OEM mis-matched tires were a mess after a few thousand miles of service. So I learned about trailer tire maintaince and trail axle alignment. When not in use, Tracker now sits on jacks with little weight on the tires.

In the spring of 2016, I made some minor tweaks to TJ's wheels. This was to allow a more easy trip around the house to the back yard, where I set up TJ for some Mars observing. I was able to make eight drawings of Mars with TJ in May and June. During this time, TJ lived outside under the cover of a Desert Storm Shield.

In July of 2016, we returned to TMI for a wonderful three day observing run. On this trip, we took advantage of NOVAC's TMI obsring program. We set up on the top of the rise with just a few folks joining us. We enjoyed cooking our own food in TMI's kitchen, with Cathy and John snoozing in a bunk house while I slept in Tracker so I didn't wake them up in the wee hours.

Below are many photos of TJ over the years

Click on most images for a larger/high resolution version of the image

Image of TJ2, Bob's 20-inch Telescope
This the scope in the spring of 2001 as TJ2.1. In this view, the scope has 1 5/8-inch OD struts. Very stable. For size, our Golden Retriever Tramp is beside the scope. The eyepiece is normally accessed via a 10-foot ladder. Wheel barrow handles allow the scope to be moved around with ease.

Image of TJ2, Bob's 20-inch Telescope
Here's an look at TJ2.1's focus cage. The original kydex cage cover has been removed. A new kydex light baffle has been installed. These changes were inspired after Bob went to the Table Mountain Star Party and saw firsthand the light weight dobsonian telescopes built in the northwest. These are talked about on Mel Bartels website. The final straw was wind problems encountered at WSP in 2001. This design reduces the wind resistence of the focus cage. The hole in the baffle is in the shadow of the secondary mirror and allows wind to escape. These changes also reduced the weight of the cage and resulted in the removal of 15 lbs of counterweight at the bottom of the scope.

Image of TJ2, Bob's 20-inch Telescope
Here's another look at the new baffle attached to the scope. I build simple, low cost scopes. You can see the 2-inch, push-pull PVC pipe focuser in this shot. The spider is homemade from sheet metal. The secondary anti-dew heater wire on the focus box is in the stored position, wrapped around two nails. When set up for all night observing, this wire is attached to a battery stored in the rocker. I've since replace this with a new 12-volt power system.

Quick Disconnect Handle System
When I built TJ2, I added a quick disconnect system for the wheel barrow handles that are used to move the scope around. The handles can be quickly attached/removed from the back of the scope, once it is loaded into the car. This is especially useful if you need to remove the handles to fit the scope into the car for transport. More details are available.

TJ2 at Delmarva NoFrills in '01
Here is TJ2.1 set up at the 2001 Delmarva No Frills party hosted by the Delmarva Star Gazers. The party is at Tuckahoe State Park on the Eastern Shore of Maryland, a short 50 minute drive from our home. While not the darkest skies around, the site is wonderful, the people are great, the size about right (~130), the weather good and the food is second to none. TJ did yeoman's work on Arp galaxy clusters at this party. The DSC's and laptop with Megastar worked the best it ever as. On this trip, I had mounted my 4.25-inch f/4 RFT "Pringles" on the back of TJ. Because of heavy dewing, I had taped some plastic above the secondary mirror.
TJ2 at Laurel Highlands Star Cruise '02
TJ2 visited the 2002 Laurel Highlands Star Cruise near Hazelton, West Virginia. The skies are pretty dark, the company was great and a good time was had by all. Little to show about TJ in this photo other than I'm using a small solar cell to charge a Marine battery.

The big news in here is the ladder. This was the first serious outing for the new Tallman Astronomers Tripod Ladder. This is a wonderful ladder that beats normal ladders hands down. The tripod is very stable, the extra width greatly increases stablity and the ladder is designed to sink into the ground, improving stabilty even more. Finally the steps are only 8-inches apart, so rarely is the eyepiece "between" steps.

TJ2 at WSP in '01
Cathy is holding a very tired 16-month-old Maggie at the 2001 Winter Star Party with TJ2 behind her. This is at the far east end of West Summerland Key, where I was able to set up and observe with very few people stopping by to gawk. You can see the "rostertail" table that attaches to TJ's rocker box and holds a laptop computer that interfaces with the Sky Commander DSC's.

TJ is so tall, it is almost impossible to use a finder scope mounted to the focus cage. Besides, the weight at the top would be a pain to counterbalance. My solution can be seen here: I mount a "riser" board to the mirror box that sticks up high enough to support a finder scope at a good height. I normally only keep a simple board that has two eyelets on it. I use this to rough aim the scope at either bright planets or at two bright stars at the start of an observing session. The DSC's use these two stars to figure out where the scope is pointed and I normally just use the DSC's to navigate for the rest of the session.

This is after about a week at the party, so we are all tired and about ready to go home after a very successful trip! We had taken the Autotrain down to FL from DC, so I wasn't able to bring a ladder on the train. We rented a 12-foot fiberglass ladder from a nearby hardware store.

A rear view of the scope
This shows the scope set up for observing as of December 2001. The laptop is on the "roster tail," the DSC is on the finder riser. I've also installed a simple indoor/outdoor temperature sensor on the riser to display the primary mirror temperature. The Sky Commander is interfaced with the laptop, so the computer shows where in the sky the telescope is pointed. I always use a dark red filter over the computer screen when observing, even when the software turns the screen red in night vision mode. For years, I used an ancient 300 Mhz Gateway Solo 2500 laptop, treasured for ready access to spare parts off Ebay, easy disassembly, low power use, few lit LED's, 13-inch screen and ability to withstand very wet, dewy nights. In 2006, this laptop died beyond repair. I was thrilled to find a replacement 2500 on Ebay for a whopping $43. A swap out of the harddrive had the replacement up and running in a few minutes.

TJ after the 2001 Leonid shower
Here TJ basks in sunrise glow the morning of the great 2001 Leonid Meteor Shower. The view is from a eastern facing overlook along Skyline Drive in Virginia. I had arrived the previous evening and used TJ to observe a number of Arp galaxies before the fireworks started around midnight, when I settled into a sleeping bag and a pile of blankets. By 1am, the overlook parking lot was grid locked. By 2am Skyline drive was a parking lot.

TJ packed up in the 1998 Saturn SW2
Almost three years after purchasing a 1998 Saturn SW2, in 2004, I finally figured out the trick for loading the rocker/mirror box into the back of the Saturn's rear hatch, which is shorter then the rocker/mirror combo is tall. With the ladder and struts on the roof, here's TJ2 ready to roll. Four-year-old Maggie likes to go observing; she gets to stay up late.

TJ set for Mars
Here's TJ set up on the drive way for some late season Mars observing in early 2006 after being rolled out from storage in the garage. The Ford Escort is TJ's most recent ride to dark skies. In 2005, TJ did fine work looking at Mars.

TJ at Goddard Space Flight Center
For "Astronomy Day" in 2006, TJ travelled to the visitor's center at the Goddard Space Flight Center in Greenbelt, Maryland. Here's TJ in the shadow of a Delta II rocket on display at the center. Deltas were used to lauch many space probes and satellites. It was windy (and very light polluted), but we still had a good time showing a couple of hundred folks the Moon, Saturn and Jupiter.

TJ at Almost Heaven Star Party, 2006
August of 2006 saw TJ's 2nd trip to Spruce Knob, a mountain in West Virginia, perhaps the darkest site on the US east coast for the Almost Heaven Star Party. Here Johny and Maggie play on the ladder. This location is at about 4,100 feet.

TJ at Greenbank Radio Observatory
In July of 2004, we attended the first Greenbank Star Quest star party, held on the grounds of the Greenbank Radio Observatory. It was a fine, fine party even though it rained, rained and rained some more. Here's TJ set up with the Greenbank Telescope in the background. The GBT is the largest moving object on land. It's 400 ft wide at the base, and more than a 1,000 ft tall when pointed up like this.

TJ2 at Astroday 2005
The Northern Virginia Astronomy Club had great weather and a huge turn out for Astronomy Day in 2005. Here's TJ set up for people to look at during the afternoon. Maggie, Johny and Cathy are along for the fun at CM Crocket Park, in Virginia. A bright first quarter Moon made any deep sky observing very difficult, but the seeing was very good and TJ provided about 75 folks an outstanding view of Saturn, as only a long focus, large aperture Newtonian can. Late in the evening, TJ dug up comet 9P/Tempel 1, three months from its encounter with NASA's Deep Impact spacecraft. While almost no work as been done on TJ over the past two years, TJ has logged over 150 Arp galaxies in more than a dozen outings.

TJ2 from space!
During 2003, TJ spent several months set up in the backyard awaiting clear nights to look at Mars. During the day, TJ was covered with a "Desert Storm II" Mylar cover. This cover is very bright silver and reflects light (and heat) very well. In 2005, while browsing the newly released satellite image option of Google Maps, we were amused to notice this image was apparently snapped while TJ was set up in the backyard. Thus, we can now see TJ from space!!!!

Ready to go home
Here TJ is packed up into the "princess" car and ready to head home after a long night of Herschel object observing at the 2009 Delmarva Star Gaze (spring).

Block production
2009. Replacement truss blocks are in production in the shop. These blocks, made from red oak did not work when the oak proved too brittle.

Cracked block
2009. Cracked and failing original solid maple truss block after a decade of use, drying and repeated hot/cold cycles.

Set up!
Set up during the 2011 Spring Delmarva Star Gaze. Rare photo of Bob during set up by Karen Jennings. Pringles is on the scope, the laptop is on the stand, but I haven't wired up the Sky Commander/computer yet. This was the 2nd night of observing at this event.

Loaded in Freddy Set up
Summer 2011, TJ gained a new family ride, a 2007 Explorer named "Freddy." Here it's loaded up for a weekend observing run to Tuckahoe (a very hot weekend!) and then later set up at the ballfield location at Tuckahoe. The kids play in the background, Cathy relaxes in a chair, while Shadow the Golden Retriever watches the photographer.

Loaded in Freddy
August, 2011, took TJ to a blockparty in Deale, MD, at the request of a friend. Had some great food, met some fun people, showed several folks the Moon, M-57, M-56, M-51 through thin clouds. Snapped this afocal image of the Moon using the Blackberry camera and the 38mm Rini eyepiece. Perhaps the first astro-image taken through TJ!

Loaded in Freddy
July 2012, TJ and the new trailer at Starquest near Greenbank, WVa. John and I camped out for several days in the shadow of the monster radio telescope. During the day, we blasted off Estes rockets and got a steam locomotive cab ride at Cass Scenic railroad.

Loaded in Freddy
Starquest 2012. Set up for observing. A new large roster tail shelf is on the scope. The trailer not only holds the telescope and ladder, but all camping equipment, including tents, stove, dishes, sleeping bags, winter coats, boots, tools, spare parts, and on and on.

First Light!
First light 2015!!! After refiguring and recoating. Memorial Day weekend, set up for friends and neighbors on our driveway. Here Cathy looks at M-104 while I chat. Photo by John Bechet.

Heating new pitch for a full size lap, 2015.

I cut pitch lap channels the old fashion way. A razor blade and elbow grease with some help from masking tape.

Nonetheless, this lap had very poor contact. Many hours were spent attempting good contact with limited success. Hot water didn't come close, but a blowtorch helped!

Mirror on top of the full size lap at the Mirror Making Seminar with lots of activity in the background. These seminars are outstanding. Good company, good work, good mirrors, great food.

Working the outer edge with a six inch lap at the mirror making seiminar. The wisdom and guidance of Steve Swayze is invaluable at this stage. What to do, how much to do and what stroke to use.

A very, very poor image of the Ross Null test of the mirror. Straight lines are the good. A careful look shows (especially at the bottom) where the band bend out, the remaining turned edge that prevents TJ from becoming a 21-inch mirror.

The vaccum chamber in which TJ got it's current coating. The mirror was hung on the left side, the heating elements are on the right. The base is the opening to the crygenic vaccum pump.

Both mirrors in their carrying case, still wrapped up after being coated. One almost hates to touch such perfection.

An early morning scene during the 2015 Almost Heaven Star Party with low laying fog around.

John photo bombs a scene of TJ at sunset at The Mountain Institute on Spruce Knob in July of 2016.

A view from TMI in 2016 facing south as we wait for sunset.

Some older pre-history images of TJ

GIF of TJ in the Jeep
Here TJ2 has been loaded in our old Jeep and the family is ready to go. There is room in the back for the dogs. The 10 foot ladder, wheel barrow handles and the loading ramps are all strapped to the roof. In 2001 we sold the Jeep (205,000 miles!) and purchased a Mini Van. The van offers a lot more options in transporting TJ2. A primary advantage of the van is bumper height: the van's bumper is 3-inches lower than the Jeep's was. This makes loading easier and less scary.

TJ at Crockett Park
This is the original TJ as it was built in Columbus, Oh. in 1987 by Bill Burton, Tom Burns and Bob Bunge. In 1987, it was compact for a 20-inch telescope, but still weighed in at about 400 lbs and required at least two people to set up. I made changes in 1994 that allowed one person setup and reduced the weight somewhat. We had originally installed handles all over the telescope. They always got in the way, so I took them off and cut hand holds in their place. Here you can see them on the front of the rocker box and the top of the middle OTA box. Here Cathy poses in front of TJ with Lady and Tramp at Crockett Park in Virginia.

TJ at Starfest,
In 1995 we drove TJ1 up to Starfest in Canada. It was a nice trip, but it was only clear one night out of four for about 3 hours! Nice dark skies, though, and good people to hang out with. We had nice views of Comet Hale-Bopp long before it blazed around Earth the next year. Here is Cathy sitting on our old wooden 10 ft ladder beside TJ. This is a pretty good view of the back of the scope and how the two boxes were attached via four wooden "L" struts. A very stable solution for holding the boxes together. For this version of TJ, I used a finder made from one of those famous Zeiss copy lenses. I found that a cheapo plastic cup fit on the front of the finder perfectly. I would only take this cup off while looking through the finder and thus never had finder dewing problems. You can also see how I cut down the edges of the rocker box to allow me to tip the assembled mirror box/center box onto the rocker using a small ammo can as a level and a little ebow grease! Beats having to find two other people to lift the OTA onto the rocker. By now, the wooden ladder has grown very old and tired. It was really shaky and would soon be replaced by a new aluminum model.

TJ at Stellafane, 1987,
For several years in the late 1980's, TJ was stored at Warren Rupp Observatory in Mansfield, Ohio. Bob actively used the big 31-inch F/7 telescope at the observatory during this time frame. Here is an "x-ray" photo of the observatory dome that shows TJ2 and ladder set up, by the door, left side of the dome. Long time observing partner Brent Archinal posed for the photo, which was taken from outside the dome from a scissors lift. The camera was mounted on a tripod and the shutter opened while the dome was rotated, to explose the entire inside of the dome.

TJ at Stellafane, 1987,
Soon after TJ1 was built, Tom Burns, myself, Bill Burton and Jay Elkes took TJ to the fabled Stellafane star party in Vermont. That was in 1987. In those days, the judges at Stellafane thumbed their noses at telescopes that weren't on equatorial mounts and were made of wood. It needed to be tilted and shiny to win an TM award. We had a pretty good time, but only Saturday night was clear and we couldn't stay up late since we needed to drive back to Ohio the next day. The highlight of the trip was that John Dobson himself was there. He surveyed TJ, complained about the open tube, commented about the long focal length, said the bearings were too stiff (they were), and added the big bang was a hoax. Here Bill Burton works on adjusting his surveyor's tools and Radio Shack pocket computer semi-digital setting circles that he hung on the side of the scope.

The famed pink A-frame Stellafane club house is in the background. Beside TJ is Tom Burn's wonderful 6-inch f/20 Tri-shief. with optics by Dick Wesseling.

TJ at Astrofest,
Right after we rebuilt Marshal's 20-inch, in 1987, we took it to the Astrofest starparty in Ill.. This is the version of the telescope I refer to as "TJ1". This is a formal portrait of the telescope - at the time a state of the art dobsonian. The finish is new, there aren't many scratches an it's all shiny! Here are some things to notice:

Bill Burton's surveyor's setting circles are mounted on the scope. There is a protractor on the side bearing. Just behind the bearing, attached to the rocker is a vertical board that held a surveyor's compass. Bill ran a program, written in BASIC, by John Kerns on an old Radio Shack pocket computer. The computer had something like 8k of RAM and could store all 110 Messier objects in memory! Input the RA and Dec, and it output the alt-alz. Dial them in and the telescope was pointed! It really worked. Richard Berry of ASTRONOMY magazine was impressed enough to run an article with a print out from Bill's computer with the code for program. But a single line of code was cut off during printing. Richard recieved dozens of letters and swore off printing computer code! Bill won an award at this party for the pointing system.

Behind TJ, is Brent Archinal's old Volkswagen pickin-up truck. I can't count the number of hours I spent following this truck around from star party to star party. For this party, Brent's truck had carried large parts of the TJ from Ohio.

Other interesting tidbits include that we had a small 50mm finder mounted on the focus box and the struts were attached with straight through bolts and wing nuts, not clamped with Ron Ravneburg's system. This version of the scope was pretty shaky. But shoot, it was big and collected lots of photons! Also shown is the original 10-foot wooden ladder. This version had an early attempt at a homemade crayford PVC pipe focuser. This didn't last long.

This also a good shot showing the original configuration of rocker box sides: squared off all the way up the top. This made putting the OTA in the rocker very difficult. It took at least three people to lift the OTA on the rocker.

It should be noted that the very next year, Dave Kriege brought his first Obsession design scope to Astrofest, making this design old, anicent and out-of-date!

TJ at Astrofest from across the field,
While exploring the telescope field at Astrofest, there was a nice 5-inch f/5 (Jaegers) refractor on display. With the owner's help, I pointed it back at TJ1, held my lensless Nikon FM2 up the focuser tube and snapped this image of Bill Burton and John Kerns shooting the bull with some nearby party goers. It looks like Bill sees me, but really, I'm 200 yards away behind a forest of telescopes. Anyone who went to Astrofest in the 1980s will remember how a row of telescopes started at one end of the big field and curved around in a big circle.

Behind TJ, you can see the second version of the Columbus Astronomical Society's 16-inch f/5.6 Stewart Telescope.

TJ in Astrofest,
Astrofest in 1987 was a sort of reunion for members of the Ohio State University Astronomy Club of the early 1980s and some various Columbusites. From left to right: John Kerns, Tom Burns, Bob Bunge, Bill Burton, JoAnne Archinal (on ladder), Brent Archinal (with ball cap), Willkie Cirker, Tony Hohenbrink, Mitch Lumen and Carl Wenning. TJ builders Tom, myself and Bill are inside the tube.

TJ in Alabama,
Marshal Holman originally ground the mirror and mounted the optics in this optical tube assembly. Sonotube, with a huge mirror box with 3/4-inch plywood, a massive rocker with 2-inch thick walls and a ground board on wheels. He rolled this scope out of a barn for observing. You can see the concrete tracks in the ground that we made. This sucker was a VERY heavy telescope. It took at least three people to lift the OTA into the very tall rocker box. Nonetheless, in 1983, this was a state-of-the-art Dobsonian telescope and one of the largest telescopes in all of Florida - amateur or professional!

Notice we reused the huge 3-inch thick altitude bearings that Marshal had turned on a wood lathe when we made TJ1. Also the very cool PVC push-pull focuser. This version of the scope also had a classic Dobsonian tailgate for removing the mirror. This scope was originally built in 1983. I believe I took this photograph in 1986 or 1984.

TJ in Alabama,
Marshal closing the mirror box gate on the original TJ. This is how the old, old dobsonians worked! Notice the chains on the side to keep the gate from folding down and allowing the mirror to fall out. Mashal cast the honeycomb pyrex mirror blank that is in Bob's "Ellie," a 12-inch Suitcase travel telescope.


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