ING Banner
Home > Astronomy > Isaac Newton Telescope

Training Opportunity

Telescope Time

For Observing

Technical information




Other information

For ING Staff (internal)

Cecilia Fariña
INT Telescope Manager

Isaac Newton Telescope

The Issac Newton Telescope (INT) has a 2.54-m diameter primary mirror. It uses a polar-disc/fork type of equatorial mount. Instruments can be mounted either at Cassegrain or Prime focus, offering the possibility to carry out both intermediate-low dispersion spectroscopy and wide-field imaging.

INT Instruments

The instruments offered at the INT are:

  • Wide Field Camera (WFC): Imaging over a 33-arcmin field with a wide variety of broad- and narrow-band filters.

  • Intermediate Dispersion Spectrograph (IDS): Medium-low resolution long-slit spectroscopy. IDS is offered with a set of 16 gratings providing dispersions in the range of 4-0.24 Å pixel-1. It can be used with Red+2 detector (default) or EEV10 detector (if requested and justified in the proposal).

Detailed descriptions to operate the telescope and instruments can be found the in the instruments web pages and links therein.

Changing from WFC to IDS and vice-versa requires daytime instrument change followed with a discretionary-time night for technical checks. These are optimally scheduled over the semester. When WFC (mounted at Prime focus) or IDS (mounted at Cassegrain focus) are in use no other instrument option is available.

Information to apply for observing time can be found at Applying for Telescope Time.

For preparing and planning observations, read the information at Planning Observations.

Observing at INT

It is essential that INT observers have considerable end-to-end observing experience with medium-sized telescopes. As there is no Observing Support Assistant (OSA) at the INT, observers are responsible for all aspects of telescope and instrument operation during the night. INT visitor observers should then be familiarized with the instrument and telescope documentation as well as health and safety issues. A detailed introduction to the telescope and instrument is given by the INT Support Astronomers (SA), who about a month in advance of the observing run will contact the PI, to confirm the instrument configuration, discuss the observing plan, etc. The SA will be at the telescope from the afternoon until about midnight of the first day of the run and will be reachable at ORM Residencia during the whole first night of the run.


  • Please read carefully the information about filling the WFC or IDS cryostat.

  • In WINTER time, before arriving to the telescope, read the recommendations and advices about Ice Safety.

  • When the laser is working at the WHT (e.g. by CANARY), the INT observers should monitor the "TELESCOPE SUMMARY" in the Laser Traffic Control System web page, to check if there is any limitation in the INT pointing due to possible collisions with the laser.

  • For any question do not hesitate to contact your INT SA, Instrument Specilist or INT Manager.

Other information

INT Brief History

The INT saw first light in 1967 in Herstmonceux, United Kingdom, the site of the Royal Greenwich Observatory. At the time, the INT was the 5th largest telescope in the world (acc. to wikipedia). Aiming at a site with better weather and sky observing conditions the INT was moved to the Roque de Los Muchachos Observatory (ORM) and resumed operations in 1984, as part of the Isaac Newton Group (ING). More information about the INT can be found on the public information web pages.

Front picture: "Moonlight", from

Top | Back

Contact:  (INT Telescope Manager)
Last modified: 17 November 2015