Millennium Telescope Project

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Millennium TelescopeProject
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Aperture Fever!
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Objectives

• Build large aperture portable telescope
• Maximise light gathering ability
• Lightweight open tube design
• Transportable to deep sky locations

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Obsession 20 F/5Completed scope
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Babcock 24 inch
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Design Goals

• Ease of construction
• Ease of assembly/disassembly
• Ease of storage and transportation
• Ease of collimation (repeatable)

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MMT Activities...
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Mirrors

• Primary Mirror (Pyrex)
• Diameter, 482 mm (19)
• Edge thickness, 38 mm (1.5)
• Focal length, 2165 mm (F/4.5)
• Calculated weight 15.6 kg (34 lb)
• Secondary Mirror (elliptical plate glass)
• Major axis, 150 mm (5.9)
• Minor axis, 106 mm (4.2)
• Thickness, 14.5 mm (0.6)

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Component Weights

• Primary Mirror 15.39 kg (33.9lb)
• Mirror cell base 5.48 kg (12.1lb)
• Wiffletree 1.79 kg (3.9lb)
• Rocker bearing (x2) 3.62kg (8.0lb)
• Al bearing runner (x2) 0.80 kg (1.8lb)
  (optional)
• Strut blocks (x8) 0.78kg (1.7lb)
• Cross bars (x2) 1.38kg (3.0lb)
• Base total 28.43 kg (62.7lb)
• (excluding Al runners)

• 8 x Struts (total) 4.11kg (9.1lb)
• Cage ring 1.10 kg (2.4lb)
• Secondary mirror 0.4 kg (0.9lb)
• Focuser (est) 0.24kg (0.5lb)
• Spider (est) 1.30kg (2.9lb)
• Viewfinder (est) 0.45kg (1.0lb)
• Telescope total 36.5kg (80.5lb)

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Mirror Cell
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Obsession 20 F/5Mirror cell assembly
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Babcock 24 F/4
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22 F4.05 DesignSecondary cage and spider
assembly with baffling
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Obsession 20 F/5Truss tube clamps
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Obsession 20 F/5Inserting mirror
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16 F/3.75 String TelescopeBase
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22 F4.05 DesignCutaway of bottom frame and
drives
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16 F/3.75 String TelescopeIn car!
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Extras - Other Designs

• Internet a great source of information providing
  inspiration!
• Ultra-light designs evolving from more
  traditional Obsession
• MMT uses best features of all these designs

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Sayre 22 inchCAD drawings
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Dan Gray 16 F/3.75 Completed scope
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16 F/3.75 String TelescopeDisassembled scope
(fits in a hatchback!)
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Gary Wolanski, USA16 F/5 Dobsonian, 40 Pound,
all-metal construction
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Jaques Civetta, France465mm Dobsonian,
fibreglass construction
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Doug Tanaka, USA12.5 F/6 String-Truss Dobsonian