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United States Naval Observatory
The Naval Observatory Flagstaff Station
The 1-meter (40-inch) Ritchey-Chretien Aplanatic reflector
Home
Our Commands
United States Naval Observatory
The Naval Observatory Flagstaff Station
The 1-meter (40-inch) Ritchey-Chretien Aplanatic reflector
ABOUT US
Mission & Vision
History
Naval Oceanography One Pager
End of Year Graphic 2022
LEADERSHIP
Commander
Technical Director
Command Master Chief
All Leadership
OUR COMMANDS
Naval Oceanographic Office
Fleet Numerical Meteorology & Oceanography Center
United States Naval Observatory
News from the Naval Observatory
Earth Orientation Department
Precise Time Department
The USNO Master Clock
The USNO Master Clock
Time Dissemination at the USNO
USNO Alternate Master Clock (AMC)
Cesium Atomic Clocks
Hydrogen Masers at the USNO
Rubidium Fountain Clocks
USNO Time Scales
International Time Scales and the BIPM
Definitions of Systems of Time
Global Positioning System
Global Positioning System Overview
USNO GPS Data Categories Explanation
CGGTTS Data Format
USNO GPS Time Transfer
Leap Seconds
GPS Information: SA, DGPS, Leap Seconds, etc.
GPS Week Number Rollover
GPS Timing Data and Information
USNO Format Explanation
USNO Computer Display Clocks
Two-Way Satellite Time Transfer (TWSTT)
Telephone Time
Network Time Protocol (NTP)
US Eastern Time Zone NTP Servers
US Mountain Time Zone Servers
DoD Customer Servers
Astronomical Applications Department
Celestial Reference Frame Department
Senior Enlisted Advisor
Careers at the USNO
Naval Oceanography Operations Command
Fleet Weather Center - Norfolk
National Ice Center
Fleet Weather Center - San Diego
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The 1-meter (40-inch) Ritchey-Chretien Reflector at NOFS
This telescope, completed in 1934, is the largest and last Ritchey-Chretien telescope designed and built by George W. Ritchey. Originally located at the main Naval Observatory in Washington, D.C., increasingly bright urban skies led to its relocation to Flagstaff and the establishment of the Flagstaff Station in 1955. This was the telescope used in the pioneering work on the polarization of starlight by John Hall and Alfred Mikesell. The original Pyrex optics were replaced with fused quartz in 1969 and are now installed in the 1-meter Austro-Croatian Telescope at Hvar Observatory, Croatia. Today this telescope is used for a variety of imaging and photometric programs by the Flagstaff Station staff.
Construction
Optics: Corning Glass Works (blanks); George W. Ritchey and Tinsley Laboratories (optical figuring)
Mounting: Designed by George W. Ritchey, manufactured by Baldwin-Southwark Corporation
Date Completed: 1934 (new quartz optics 1969)
Cost (as completed): $76,000
Optical Design: Ritchey-Chretien
Effective Focal Length: 7.3 meters
Overall Focal Ratio: f/7.3
Focal Plane Scale: 28.2 arcsec/mm
Primary Mirror
Diameter: 1.0 meter (40 inches)
Material: Fused Silica
Weight: 270 kg (600 lbs)
Figure: Modified Concave Hyperboloid
Focal Ratio: f/4
Secondary Mirror
Diameter: 46 cm (18 inches)
Material: fused silica
Weight: 27 kg (60 lbs)
Figure: Modified Convex Hyperboloid
Magnification: 1.81
Total Weight (Optics, Tube and Mount): 8200 kg (9 tons)
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