Isaac Roberts Observatory


October 25, 2021

The Isaac Roberts Observatory (in English: Isaac Roberts’s Observatory) is an old observatory, now defunct, that was installed in the private house of British astronomer Isaac Roberts. It was located in the English town of Crowborough, county of Sussex, and remained in operation from 1890, when Roberts settled there, until his death in 1904. The observatory continues to be listed on the Observatory Code List of the Minor Planet Center with code 001. [1]


Isaac Roberts began his astronomical observations from the year 1878, [2] and from very early on he saw the need to have the best possible observation conditions for the photographic exhibitions that he carried out. This factor, together with the fact that he also suffered from chronic bronchitis and needed a better climate for his health, was what motivated him to find a suitable location for his observations. In 1885 he received a copy of Charles L. Prince's Observations upon the Topography and Climate of Crowborough Hill, Sussex, describing and praising the conditions in the area, precisely those required by Roberts. Prince himself sold Roberts part of his property, four acres (1.6 hectares), where he built his house and in it a dome to house his telescopes. Roberts gave him the name of Starfield, Field of Stars, moving there in 1890. In his new house and observatory he continued his work, which earned him, among other awards, the Gold Medal of the Royal Astronomical Society of London, until his death. in 1904. [3] After his death the house was sold on several occasions until in 1928 it was bought by the local government of the area to turn it into his offices. In 1935 some expansion works were carried out that led to the disappearance of the observatory dome. Finally in the 1980s, due to the growth of the needs of the local government, the house was sold and demolished to build new homes. The name of Starfield remains giving name to this new development. [3]


The observatory was located on the summit of Crowborough Hill, a hill approximately 250 meters above sea level, the highest point in the surrounding region. The buildings in his house had only one story to allow the telescopes to be lowered to as low as 20º above the horizon when focused over the rooftops of the house. Attached to the observatory there were rooms dedicated to a photographic laboratory, with a dark room and instruments for increasing photographs. The observatory was connected to his private home by a corridor that opened, among other rooms, a library. The dome of the observatory was hemispherical, it was built of wood covered with copper plates on the outside and covered an area of ​​almost 2 m². It had two openings of approximately 120 cm each, closed with gates that opened, the lower half sliding horizontally with respect to the base of the dome and the upper half sliding over the dome. [4]


Two telescopes were housed in the observatory, a 7-inch (178 mm) diameter refractor from the manufacturer Cooke, purchased by Roberts in 1878; and a reflector 20 inches (508 mm) in diameter, and 100 inches (2,450 m) focal length, [5] manufactured by Grubb and purchased in 1886. Isaac Roberts came into contact with the astronomer William Huggins who arranged the mount. of the 20-inch reflector on the declination axis of the 7-inch refractor instead of its counterweight. In this way, both telescopes had independent declination movement while the right ascension tracking clock was common to both. [5] [6] After Roberts death in 1904, both telescopes were auctioned and sold to the Royal Observatory.

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