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Tag: telescope
Rewiring a Celestron NexStar Telescope
The original NexStar telescopes are great instruments. Ours has seen many uses, from dark skies to not so dark skies as it has been set up in the Arizona Desert, the summit of Mauna Kea, or various school yards and resorts for public viewing. It has been used as a visual instrument, a photographic ‘scope, even done a little real work.
For the most part the scope has worked well, and has been well maintained, even updated with the latest hand pad controller. But on occasion there is a problem… connection issues would crop up. The dreaded “No Response 16” or “No Response 17” errors would appear, indicating that the motor control board is not talking. This would result in having to power cycle and realign the telescope.
Lately the errors have become more problematic. The last straw was a public event I recently used the telescope for, setting up the telescope for Halloween. Continual errors plagued the evening, a constant struggle. While the scope usually tracked, I could not use GOTO as each alignment was quickly off by just enough to be useless.
I have had the telescope apart too often in attempts to fix this, inspecting and re-seating the cables. This usually works, the problem will go away, for a while.
In general I like what I see inside the telescope. A well designed piece of kit with good components. Decades of taking gear apart have provided me so many examples of poor or good design. Inside the NexStar I just like what I see. The telescope is easy to get apart, just a few screws to remove each cover, exposing everything you might need to work on. The designers of this telescope obviously took pride in their work, it shows.
The exception to this is the wiring. There are a number of issues that can create trouble. Or rather there were a few issues, I just took care of that…
Continue reading “Rewiring a Celestron NexStar Telescope”Night of The Dobs
Star parties at Hale Pohaku are very informal affairs. You never really know who is and who is not going to show up. We just don’t plan that much.
It had just been too long, I had not had a good night out with the telescope for months. This dark moon Saturday was not going to be missed, I packed up Deep Violet and headed for The Mountain. I knew a few folks would be there, certainly Cliff and Tony. The rest of the folks were a surprise to me. As the evening progressed more and more ‘scopes showed up, a few more familiar voices in the darkness.
The only real issue was the wind, it was annoying. A couple of us moved our telescopes into the patio area of the MKVIS, where the building offered some shelter at the expense of blocking some of the sky.
Stars over the Nickel
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40″ Nickel Viewing
The view was pleasing sharp and crisp, revealing decent optics and steady air over the mountain. I could just make out the central star on M57, something I had only done before with and even larger telescope.
Control the Great Refractor
The instrument may date to the 1800’s but at that time it was powered by water and muscle as there was no electricity on the mountain. It was not until much later, in the middle of the twentieth century that the telescope was refitted with electrical controls and motors.
Atop Mt. Hamilton
The visitor directions on the website had specifically cautioned that the summit road was curvy, something I found to be a drastic understatement. From the very bottom it is curve after curve all the way up, with almost no straight sections. S-curves followed sharp bends leading to hairpins. Nearer the observatory the curve intensity only increases as the road narrows. Local history indicates that the horse-drawn wagons that transported heavy equipment up this road could not negotiate steep grades, the only solution was to follow the contour of the mountain, resulting in an incredibly curvy road.
On a sunny Saturday afternoon there were other users, the road is apparently popular with local cyclists. With the density of the sharp curves there was often little choice but to follow at bicycle speeds at times. I would much rather drive up Mauna Kea than this road again. Next time up Saddle to the summit I will recall Mt. Hamilton road and consider myself lucky.
The reason I was climbing this winding road was simply to be a tourist. Unlike the previous seven days, this day was to be fun. For much of the previous week there had been full day sessions of lectures and labs covering the intricacies of adaptive optics systems. Spending a full week in Santa Cruz might be considered a vacation, aside from the fact there had been very little open time to explore the surrounding area. There was only one open day in my travel plans, and I had specific plans for that day, a visit to an observatory.
Postcard from the Summit – Azimuth Wrap
The massive set of cables going into the telescope must twist as the telescope rotates. Besides cables there are also hoses to carry high pressure oil, glycol coolant and compressed air. To accommodate the rotation, these cables and hoses go through a large assembly called the Azimuth Wrap. Looking a bit like an oversize bicycle chain with cable laced through the links, the wrap insures the cable does not kink, tangle or stretch as the telescope sweeps back and forth.
Lacing new cable through the wrap is an intricate task of threading through the metal comb that supports the cables in each link. See the little pink one in the middle, just did that…
Postcard from the Summit – Tertiary Tower
