The Zucchi-JTK3 (2013-2015)

My second telescope-making project is this 12.5″ – f/6 Newtonian. A diary of the project from my acquisition of a mirror blank in summer 2013 to first light in early 2015 can be found in the following pages. First light was 11 April 2015 on campus in Washington, DC. Two introductory points: the one on my building priorities in undertaking this particular project; the other on its christening as the Zucchi-JTK3.

(1) Designing priorities for the Zucchi-JTK3:

  • the telescope should be transportable but need not be minimalist.
    • transportable means I must easily be able to pick up each piece and place it in a Corolla. Thus,
      • no single part heavier than 30 lbs.
      • or longer than 48″.
    • the problem with minimalism is that much of this telescope’s use will be in highly light polluted Washington, D.C. Thus,
      • Open tube use is out of the question, and
      • above-the-focuser baffling is essential.
  • I have decided against a truss system of poles. I’m sure I would lose or damage one, and setting up an eight-piece truss system at dusk and tearing it down at midnight don’t strike me as fun. Alternatives will have to be invented.
  •  I wanted the longest focal length that would not require a ladder for viewing up to 70° altitude. [Stargazing above 70° is hard with a Dobsonian anyway (the “Dobsonian hole”), and the high point of the ecliptic in the sky from Washington DC is at or below 70° ten months of the year.] The blank was 12.5″x2″. I’m 191 cm tall; and with a little trigonometry, I settled on f/6.

A final point on matters of design: I’m an amateur mirror grinder, woodworker, and stargazer. This is a hobby for me, and I do it first and foremost for my own health and satisfaction. I’m really happy that other people enjoy what I can share of it, but I have no profeBauhaus-Designssional aspirations for what it “produces.” I want each of these projects to get me to learn how to do something better and something new.

Aspects of the final tube design and aesthetics follow from this wandering curiosity of mine. So my first scope is mainly oak; this one is maple. Parts of my first scope are stained (a little); parts of this scope I dyed. My first scope looks colonial; I attempted a little Bauhaus with this one. My fall-back goal to these amateurish endeavors: at the very least, given the chance that a telescope doesn’t work as such, it needs to look interesting enough to put in my living room as a conversation piece!

(2) Its name: the Zucchi-JTK3. Since the first mirror project I took on was the refurbishing of a 6″ f/8 originally created by my grandfather in the late 50s, I’ve been dubbing my mirror projects with his initials. Thus the mirror in this telescope is the JTK3.

Engraving from Zucchi's Optica philosophica

Engraving from Zucchi’s Optica philosophica

The scope itself I’ve named after Niccolò Zucchi SJ (1586-1670). Zucchi was a professor at the Roman College for the related fields of mathematics, physics, and astronomy. As an observational astronomer, Zucchi is the first to report bands on Jupiter and spots on Mars. He maintained a friendly, scholarly correspondence with Johannes Kepler, whom he met at the Imperial court (the Emperor Rudolf II was a leading astronomical Maecenas at the time).

Ca 1610 Zucchi experimented with using a lens to observe the image produced by a brass, concave mirror, in effect, a reflecting telescope, and apparently the first such attempt. While he himself did not pursue this design further, his notes, recorded in his Optica philosophica, were reference for later inventors. The basic reflector telescope design today is referred to as “newtonian.” The “Zucchi” is thus a “newtonian” telescope.

Thanks for reading. Enjoy, I hope, what you find.

Clear skies,

David

“The greatest consolation that he received at this time was from gazing at the sky and stars, and this he often did and for quite a long time.” Ignatius of Loyola, Acta, §11.

 

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