U.s. naval observatory disk map moon6/5/2023 ![]() In 1857 in Monthly Notices of the Royal Astronomical Society, Clark and Dawes reported a slew of new double stars - many of which had previously gone undetected by much larger telescopes. An impressed Dawes gave him more targets to attempt and commissioned a 7.5-inch refractor from him. Clark told Dawes of pairs he had been able to split with his telescopes. But Clark’s exceptional eye and craftsmanship came to light after he struck up correspondence with British astronomer William Rutter Dawes, an expert on double stars. Their tools were crude, and Boston’s academic elite looked down on Clark’s lack of formal training. Unfortunately, they were not getting much work for astronomy. Alvan Clark & Sons took on all sorts of machining jobs, but their true passion was constructing telescopes and grinding and polishing lenses. In the 1850s, he and his two sons had a machine shop in Cambridgeport, Massachusetts. Unlike so many other great telescopes of its era, the USNO 26-inch has remained a scientific workhorse well into the age of space exploration and digital imaging, building on its legacy even today.Īlvan Clark was an inventor, portrait painter, and self-taught optician. But what is perhaps most remarkable about this telescope is its longevity. When it was completed in 1873, it was the world’s largest telescope, vaulting the USNO back into the ranks of elite observatories. This year, that 26-inch refractor turns 150 years old. That year, in a report to the Navy’s bureau chief of navigation, the USNO’s superintendent Benjamin Sands lamented: “The comparatively small size of the instrument prevents it from entering into competition with many telescopes of other observatories in the observation of faint objects.” Even more embarrassing, the 9.6-inch scope was not “at all comparable with many owned by colleges, observatories and private individuals throughout the country.” Sands added: “This will seem the more remarkable since the most successful living constructor of telescopes is an American - Alvan Clark of Cambridge, Massachusetts.”įive years later, the USNO was rewarded with the most powerful instrument that the renowned Alvan Clark & Sons firm had ever built. The largest telescope at the USNO was a 9.6-inch refractor - inadequate for tackling many of the most important observations of the era, like the moons of the outer planets. Despite its importance as the nation’s official timekeeper and prestige as an astronomical research institute, its equipment was lagging in one crucial aspect: size. ![]() It was 1868, and the United States Naval Observatory (USNO) had a problem on its hands. ![]()
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