The Isaac Newton Group of Telescopes (ING) consists of the William Herschel
Telescope (WHT), the Isaac Newton Telescope (INT) and the Jacobus Kapteyn
Telescope (JKT). The WHT, with its 4.2m diameter primary mirror, is the largest
in Western Europe. It was first operational in August 1987. It is a general
purpose telescope equipped with instruments for a wide range of astronomical
observations. The INT was originally used at Herstmonceux in the United Kingdom,
but was moved to La Palma in 1979 and rebuilt with a new mirror and new instrumentation.
It has a 2.54m diameter primary mirror and is mostly used for wide-field
imaging and spectroscopy. The JKT has a primary mirror of 1.0m diameter.
It is mainly used for observing relatively bright objects. Both the INT and
the JKT were first operational in May 1984.
The WHT has an altazimuth mount with a f/2.5 parabolic primary mirror. The
WHT is of classical Cassegrain optical configuration. The paraboloidal primary
mirror is made of a glass-ceramic material (Cervit) having near-zero coefficient
of expansion over the operating temperature range. Instruments can be mounted
at the corrected f/2.81 prime focus, f/11 cassegrain focus, or either of
two f/11 Nasmyth foci. The WHT is of classical Cassegrain optical configuration.
The primary mirror is made of a glass-ceramic material (Cervit) having near-zero
coefficient of expansion over the operating temperature range, and it weighs
16.5 tonnes. When not operating at prime focus, a convex hyperboloidal secondary
mirror, made of Zerodur, 1.0m in diameter, directs the light through a central
hole in the primary mirror to the main instrumentation mounted at the Cassegrain
focus beneath the primary mirror cell. The telescope also incorporates a
third main mirror, a flat, angled at 45 degrees, which can be motor-driven
into position at the intersection of the axes, just above the primary mirror,
so that the light from the secondary is diverted sideways either through
one of the altitude bearings to the Nasmyth platforms.
The INT has a primary mirror with a focal ratio of f/2.94. It uses a polar-disc/fork
type of equatorial mount. Instruments can be mounted at the corrected f/3.29
Prime or f/15 Cassegrain foci. The optical system of the INT is a conventional
Cassegrain with a paraboloidal primary mirror and a hyperboloidal secondary.
It weighs 4.4 tonnes and it is made of Zerodur.
The JKT has a parabolic primary mirror of diameter 1.0m and a focal length
of 4.596m. It weighs 215kg. It is equatorially mounted, on a cross-axis mount.
The JKT has two optical configurations: Harmer-Wynne and Cassegrain. The
former one uses a f/8 spherical secondary and the latter one a f/15 hyperbolic
secondary. The two optical systems share the same parabolic primary mirror.
At present only the Cassegrain configuration is available and instruments
mount at the Cassegrain focus.
The ING operates the three telescopes on behalf of the Particle Physics and
Astronomy Research Council (PPARC) of the United Kingdom and the Nederlandse
Organisatie voor Wetenschappelijk Onderzoek (NWO) of the Netherlands.
The following table shows each telescope’s location:
Ground Floor Height
The ING is located at the Observatorio del Roque de Los Muchachos (ORM),
on the island of La Palma. The ORM, which is the principal European northern
hemisphere observatory, is owned by the Instituto de Astrofísica de
Canarias (IAC). The operation of the site is overseen by an International
Scientific Committee, or Comité Científico Internacional (CCI).
Financial and operational matters of common interest are dealt with by appropriate
The observatory also includes the Carlsberg Meridian Telescope, the 3.6m
Italian Galileo National Telescope, the 2.5m Nordic Optical Telescope, the
60cm telescope of the Swedish Royal Academy of Sciences, the 0.97cm New Swedish
Solar Telescope, the 45cm Dutch Open Solar Telescope, the German High Energy
Gamma-Ray Array and the Belgian 1.2m Mercator Telescope.
The observatory occupies an area of 1.89 square kilometres approximately
2,350m above sea level on the highest peak of the Caldera de Taburiente National
Park, in the Palmeran district of Garafía. La Palma is one of the
westerly islands of the Canary Archipiélago and the Canary Islands
are an autonomous region of Spain.
The site was chosen after an extensive search for a location with clear,
dark skies all the year around. All tests proved that the Roque de Los Muchachos
is one of the best astronomical sites in the world. The remoteness of the
island and its lack of urban development ensure that the night sky at the
observatory is free from artificial light pollution. The continued quality
of the night sky is protected by law. The mountain-top site has a remarkably
stable atmosphere, owing to the local topography. The mountain has a smooth
convex contour facing the prevailing northerly wind and the air-flow is comparatively
undisturbed, allowing sharp and stable images of the night sky.
The construction, operation, and development of the ING telescopes is the
result of a collaboration between the United Kingdom and the Netherlands.
The site is provided by Spain, and in return Spanish astronomers receive
20 per cent of the observing time on the telescopes. A further 75 per cent
is shared by the United Kingdom and the Netherlands. On the JKT the international
collaboration embraces astronomers from Ireland. The remaining 5 per cent
is reserved for large scientific projects to promote international collaboration
between institutions of the CCI member countries.
Many of the state-of-art telescope and instrument components are custom-built.
New instruments are designed and built by technology groups mainly in the
United Kingdom, the Netherlands, and Spain, with whom the ING maintains close
links, and by astronomers and engineers working at ING.
THE INTERNATIONAL AGREEMENTS
The international agreements by which the Roque de Los Muchachos and the
Teide Observatories were brought into existence were signed on La Palma on
26 May 1979. The participant nations at that time were Spain, the United
Kingdom, Sweden and Denmark. Later other European countries also signed the
agreements. Infrastructural services including roads, communications, power
supplies as well as meals and accommodation facilities have been provided
by the Spanish side. In return for the use of the observatory and its facilities
all foreign user institutions make 20 per cent of time on their telescopes
available to Spanish observers. Representatives of the participant institutions
meet together as the International Scientific Committee, or Comité
Científico Internacional (CCI).
The inauguration of the Canary Islands observatories took place on 29 June
1985 in the presence of the monarchs and members of the Royal Families of
five European countries, and the Presidents of another two.
THE ING BOARD AND THE INSTRUMENTATION WORKING GROUP
The PPARC and the NWO have entered into collaborative agreements for the
operation of and the sharing of observing time on the ING telescopes. The
ING Board has been set up to oversee the operation of this agreement, to
foster and develop collaboration between astronomers of the United Kingdom
and the Netherlands and to ensure that the telescope installations are maintained
in the forefront of world astronomy. In particular, the ING Board oversees
the programme of instrumentation development, determines the programme of
operation and maintenance of the installations, approves annual budgets and
forward estimates and determines the arrangements for the allocation of observing
The Instrumentation Working Group (IWG) provides scientifically informed
advice on the instrumentation programme for the ING telescopes. The IWG fulfils
an important function as intermediate between ING and the user community.
TELESCOPE TIME AND DATA OWNERSHIP
Spain has at its disposal 20 per cent of the observing time on each of the
three telescopes, and it is the responsibility of the
IAC to make this time available to Spanish institutions and others, via the
Comité para la Asignación de Tiempos (CAT). A further 5 per
cent of the observing time is for international collaborative programmes
between institutions of the CCI member countries. It is intended that this
time be used for the study of one, or a few, broad topics each year by several
telescopes. This time is allocated by the CCI.
The remaining 75 per cent of the time is distributed as follows. The PPARC
and NWO share the time on all three telescopes with 80 per cent being allocated
to PPARC and 20 per cent to NWO. The PPARC-NWO ING BOARD has delegated the
task of time allocation to astronomers to the PPARC Panel for the Allocation
of Telescope Time (PATT) and the NFRA Programme Committee (PC), which have
set up procedures for achieving the 80 : 20 ratio whilst respecting the separate
priorities of the United Kingdom and Dutch communities. The PPARC has made
27 nights per year of its share on the JKT available to the National Board
of Science and Technology of Ireland (NBST) and the Dublin Institute for
Advanced Studies (DIAS). The Irish Advisory Committee for La Palma set up
by the two Irish Institutions has decided that JKT proposals by Irish astronomers
should also be submitted to PATT. Irish astronomers are not however discouraged
from applying for use of the other telescopes of the ING. PATT includes representatives
from the Republic of Ireland. All the above agreements envisage that
observing time shall be distributed equitably over the different seasons
of the year and phases of the Moon.
Notwithstanding the above, any astronomer, irrespective of nationality or
affiliation, may apply for observing time on the ING. Astronomers who are
working at an institute in one of the partner countries should apply through
the route appropriate to their nationality or the nationality of their institute.
Time is allocated in two semesters, from 1 February to 31 July (semester
A) and from 1 August to 31 January (semester B). The corresponding closing
dates are in September and March respectively. Decisions on time allocations
are made on the basis of scientific merit and technical feasibility of the
The PPARC-NWO ING Board and the CCI have decided that ING policy is that
data belongs exclusively to those who collected it for a period of one year,
after which it is available in a common archive for all astronomers. It may
be used at any time for engineering or instrumental investigations in approved
programmes carried out to improve facilities provided at the observatory.
Service observations which are made by support astronomers at the request
of others are similarly treated. However, calibration data may well be used
for more than one observation and may therefore be available in common to
several groups. It may happen that identical or similar service observations
are requested by two or more groups. Requests which are approved before the
data are taken may be satisfied by requiring the data to be held in common
by the several groups. It is up to them how they organise themselves to process,
analyse, relate to other work, and eventually publish the data.
Requests for observations from programmes already executed on the telescopes
should be referred to the original owners of the data, and/or to the data
archive. This is the policy whether or not the data were obtained by PATT,
NFRA PC, or CAT scheduled astronomers, or by service requests.