Isaac Newton Telescope

Isaac Newton Telescope (Since 1984)

The INT dome by moonlight
Organisation Isaac Newton Group of Telescopes
Location(s) Roque de los Muchachos Observatory, La Palma, Canary Islands (1984–Present)
Coordinates 28°45′44″N 17°52′39″W / 28.7622°N 17.8775°W / 28.7622; -17.8775Coordinates: 28°45′44″N 17°52′39″W / 28.7622°N 17.8775°W / 28.7622; -17.8775
Wavelength Optical / infrared
Built 1979–1984 (Moved from England)
Telescope style

Two configurations:[1]

Diameter 2.54 m (100 in)
Collecting area ~5m2
Focal length 8.36 m (329 in)
Mounting Fork type equatorial
Enclosure Spherical
Website INT Homepage
Isaac Newton Telescope (1967–1979)

The old building at Herstmonceux Castle in England
Location(s) Royal Greenwich Observatory, Herstmonceux Castle, England (1967–1979)
Coordinates 28°45′44″N 17°52′39″W / 28.7622°N 17.8775°W / 28.7622; -17.8775Coordinates: 28°45′44″N 17°52′39″W / 28.7622°N 17.8775°W / 28.7622; -17.8775
Wavelength Optical
Built 1967
Telescope style Cassegrain
Diameter 249 cm (98 in.) [2]
Collecting area ~5m2
Focal length 8.36m (329 in.)
Mounting Fork type equatorial
Enclosure Spherical
Website INT Homepage

The Isaac Newton Telescope or INT is a 2.54 m (100 in.) optical telescope run by the ING at Roque de los Muchachos Observatory on La Palma in the Canary Islands since 1984.

Originally it was situated at Herstmonceux Castle in Sussex, England, which was the site of the Royal Greenwich Observatory after it moved away from Greenwich due to light pollution. It was inaugurated in 1967 by Queen Elizabeth II.[3] The telescope is now one member of the Isaac Newton Group of Telescopes.

However, Herstmonceux suffered from poor weather, and the advent of mass air travel made it plausible for UK astronomers to run an overseas observatory. In 1979, the INT was shipped to La Palma, where it has remained ever since. It saw its second first light in 1984, with a video camera.[4][5]

Today, it is used mostly with the Wide Field Camera (WFC), a four CCD instrument with a field of view of 0.56x0.56 square degrees which was commissioned in 1997. The other main instrument available at the INT is the Intermediate Dispersion Spectrograph (IDS), recently re-introduced having been unavailable for a period of several years.

Technical detail since 1984

The La Palma INT is a Cassegrain telescope, with a 2.54 m (100 in) diameter primary mirror and a focal length of 8.36 m (329 in). The mirror weighs 4361 kg (9614 lb), and is supported by a polar disc/fork type equatorial mounting. The total weight of the telescope is around 90 tons. The f/3.29 Prime focus, used with the WFC, allows an unvignetted field of view of 40 arcminutes (approximately 0.3 square degrees). There is also a secondary focal station, the f/15 Cassegrain focus, which possesses a 20 arcminute field of view and is the mount point for the IDS. The telescopes second first light was done by video.[5]

The pointing accuracy of the telescope is around 5 arcseconds, but a sophisticated autoguider, which tracks a given guide star and makes small corrections to the telescope tracking, allows a guiding accuracy of better than an arcsecond on better than 20th magnitude guide stars in support of the typical 0.8-1.5 arcsec seeing at the INT.

Isaac Newton Telescope Mirror, with the primary mirror cover petals almost closed.
International Year of Astronomy commemorative coin featuring the Isaac Newton Telescope.

Contemporaries

The Isaac Newton Telescope was a very large telescope for its day, and the largest in England. It was a little smaller in aperture than the 100-inch Hooker telescope in the United States, but much newer. It originally had a 98-inch mirror when in England, but given a new, larger 100-inch mirror by Grubb Parsons after the move.[6][7] INT locations are Herstmonceux Castle (1967–79) then ORM (1984–).

1967

The INT was inaugurated by Queen Elizabeth II in 1967.

Largest optical telescopes 1967:

# Name /
Observatory
Image Aperture Altitude First
Light
1 5m Hale Telescope
Palomar Obs.
200″
508 cm
1713 m
(5620 ft)
1949
2 C. Donald Shane telescope
Lick Observatory
120″
305 cm
1283 m
(4209 ft)
1959
3 Shajn 2.6m (Crimean 102 in.)
Crimean Astrophysical Obs.
102″
260 cm
600 m
(1969 ft) [8]
1961
4 Hooker Telescope
Mount Wilson Obs.
100″
254 cm
1742 m
(5715 ft)
1917
5 Isaac Newton Telescope
Royal Greenwich Obs. (1967-1979)
98″
249 cm
1965 [4]
6 KPNO 2.1 m Telescope
Kitt Peak National Obs.
83″
211 cm
2,070 m
6791 ft
1964
7 Otto Struve Telescope
McDonald Obs.
82″
208 cm
2070 m
(6791 ft)
1939

1984

INT began its new life atop the Canary Island of La Palma, a Spanish mountain island, in 1984, with a new mirror and dome.

Large visible-light optical ground telescopes in 1984:

Name /
Observatory
Image Aperture M1
Area
Altitude First
Light
n BTA-6
Special Astrophysical Obs
238″
605 cm
26 m² 2070 m
(6791 ft)
1975
n Hale Telescope
Palomar Obs.
200″
508 cm
20 m² 1713 m
(5620 ft)
1949
n Multiple Mirror Telescope
Fred Lawrence Whipple Obs.
1.8 m x 6
6+ or 4.7 m
2617 m
(8585 ft)
1979
n Mayall Telescope
Kitt Peak National Obs.
158″
401 cm
10 m² 2120 m
(6955 ft)
1973
s CTIO 4m/Blanco
CTIO Obs.
158″
401 cm
10 m² 2200 m
(7217 ft)
1976
s Anglo-Australian Telescope
Siding Spring Obs.
153″
389 cm
1742 m
(5715 ft)
1974
n CFH telescope
Mauna Kea Obs.
141″
358 cm
4205 m
(13,800 ft)
1979
s ESO 3.6 m Telescope
ESO La Silla Obs.
140″
357 cm
8.8 m² 2400 m
(7874 ft)
1977
n MPI-CAHA 3.5m
Calar Alto Obs.
138″
350 cm
9 m²
[9]
2168 m
(7,113 ft)
1984
n Shane Telescope
Lick Observatory
120″
305 cm
1283 m
(4209 ft)
1959
n Harlan J. Smith Telescope
McDonald Observatory
107″
270 cm
2070 m
(6791 ft)
1968
n Shajn 2.6m (Crimean 102 in.)
Crimean Astrophysical Obs.
102″
260 cm
600 m
(1969 ft) [8]
1961
n BAO 2.6 telescope
Byurakan Astrophysical Obs.
102″
260 cm
1500 m
(5000 ft)
1976
n Isaac Newton Telescope
ORM Obs. (1980–Present)
100″
254 cm
2396 m
(7,860 ft)
1984 [4]
s du Pont telescope
Las Campanas Obs.
100″
254 cm
2380 m
(7841 ft)
1976
n Hooker Telescope
Mount Wilson Obs.
100″
254 cm
1742 m
(5715 ft)
1917

See also

References

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