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ING Instrumentation Update 2023-2024


  • The WHT will be entirely devoted to WEAVE in 2023. Open-time access to each of the WEAVE modes will be offered after commissioning for that mode is completed. As of Feb 2023, the WEAVE LIFU mode is being offered for semester 23B.
  • The INT will offer WFC and IDS for all of 2023A/B and for, possibly, a fraction of 2024A.


This page reports the current status of the instrumentation plans for the WHT and INT.

During 2023 and 2024, the ING continues a series of changes in the availability of instrumentation at the WHT and INT, driven by the upcoming commissioning of new instruments. The information below will help you to make the most of the evolving observing opportunities driven by the schedules for these instruments.

We welcome your questions, comments or requests for clarification. Please email Chris Benn, ING Head of Astronomy ( or me (

Changes at the WHT

  1. New instrument WEAVE. As of this writing, the WEAVE multi-fibre and multi-IFU spectrograph is being commissioned. After each WEAVE mode is successfully commissioned, a science verification programme will be carried out. This will be followed by the start of science surveys and open-time access for that mode.

  2. Time distribution and instrumentation in the WEAVE surveys era. We encourage WHT users to read the WHT telescope time document in

    In summary, the start of the WEAVE surveys will mark the transition of the WHT from a classical observing telescope to a mainly survey telescope. We will retain 30% as open time for allocation by the TACs. The instrumentation offered in open time will be WEAVE, ISIS, LIRIS, ACAM and visitor instruments. For visitor instruments the Cassegrain, GRACE (Nasmyth) and prime focal stations will be available. At prime, only the (pre-WEAVE) 40-arcmin corrector will be available for visitor instruments.

    Given the complexity of mounting and dismounting WEAVE, we plan the first science period with WEAVE to be significantly-longer than implied by the 9-month instrument change cadence advertised in previous communications. A plausible duration will be 2 years. During this time, the 30% open time will be entirely devoted to WEAVE open-time observations. The instrument change policy is currently under revision.

Changes at the INT

  1. HARPS3. The Cambridge-led THE (Terra-Hunting Experiment) Consortium is making steady progress in the construction of HARPS3 for deployment at the INT. HARPS3 is a high-resolution stabilised spectrograph which will conduct a 10-year survey aimed at discovering Earth-mass planets. The THE Consortium will carry out a full upgrade of the INT to allow for robotic operation. Half of the INT time will be devoted to the THE survey, the remainder being available as open time (most likely for robotic observations with HARPS3) to be allocated by the TACs.

  2. Downtime. The INT upgrade schedule calls for a stand-down during the first half of 2024, and the start of science surveys in the fall of 2024. We will provide regular updates on these plans, to allow users proper planning of their observing programmes.

  3. Instrument availability. Users may safely assume that the WFC and IDS will remain available throughout 2023A,B and possibly for part of 2024A.

    Both instruments will be decommissioned once the INT upgrade starts.

Marc Balcells, ING Director
Updated to 17th February 2023

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