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] Newtonian prime focus (f/3.29) Cassegrain (f/15)
Diameter	2.54 m (100 in)
Collecting area	~5m2
Focal length	8.36 m (329 in)
Mounting	Fork type equatorial
Dome	Spherical
Website	INT Homepage
Related media on Wikimedia Commons

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
Dome	Spherical
Website	INT Homepage
Related media on Wikimedia Commons

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. 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.^[3][4]

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.^[4]

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.^[5][6] 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) [7]	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 [3]
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 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	m²	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	m²	1742 m (5715 ft)	1974
n	CFH telescope Mauna Kea Obs.		141″ 358 cm	m²	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 [8]	2168 m (7,113 ft)	1984
n	Shane Telescope Lick Observatory		120″ 305 cm	m²	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) [7]	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 [3]
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

• Newton's Reflector
• International Year of Astronomy commemorative coin

References

External links

• INT Homepage
• Merrifield, Michael; Barrena, Rafael. "Isaac Newton Telescope". Deep Sky Videos. Brady Haran.