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ING Instrumentation Update 2021-2022

Summary of changes

  • The WHT will be entirely devoted to WEAVE in 2021 and 2022. Open-time access to WEAVE will be offered after WEAVE commissioning is completed, via a special call if needed.
  • The INT will offer WFC and IDS for all of 2022A and 2022B.


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

During 2021 and 2022, 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 at both telescopes. The information below will help you to make the most of the evolving observing opportunities driven by the schedules for these instruments.

Plans outlined here are likely to evolve as we adapt to the landscape of the covid pandemic. Travel restrictions will continue to force ING, and visitors, to modify our integration plans for WEAVE, as well as for the developments at the INT.

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

Marc Balcells (ING Director)
Updated to 15th August 2021

Changes at the WHT

  1. New survey instrument WEAVE. Integration of the WEAVE multi-fibre and multi-IFU spectrograph is in progress subject to the constraints imposed by the Covid-19 pandemic. Most of 2021 is being taken up by the calibration and tuning of the fibre positioner as we work toward integration on the telescope. This will be followed by first light, commissioning and science verification. The start of the WEAVE science surveys is expected for 2022A or 2022B. Once commissioning is completed, open-time access to WEAVE (see point 3 below) will be offered via a special call if needed.

  2. WHT telescope time in the WEAVE years. We encourage WHT users to read the WHT telescope time document in:
    A summary is provided below.

  3. Time distribution and instrumentation in the WEAVE surveys era. We remind users that 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. Open time will be advertised to the community after commissioning of WEAVE is completed.

    Given the complexity of mounting and dismounting WEAVE, the current plan is to change to other instruments with a cadence of 9 months. Open-time accessibility to all RAs will be guaranteed, but only with WEAVE - the scheduling software will handle WEAVE open-time OBs (observing blocks) in the same way as it handles WEAVE survey OBs.

  4. Nasmyth visitor instruments. Visitor instruments requiring a Nasmyth focus (including those instruments formerly deployed in the GHRIL enclosure) can be deployed (when WEAVE is off the telescope) in the GRACE Nasmyth enclosure. GHRIL is no longer available for visiting instrtuments (the WEAVE spectrograph is now housed in that enclosure). Teams proposing to observe with Nasmyth visitor instruments in future semesters need to communicate with the observatory to ensure any required changes are understood and agreed well in advance.

Changes at the INT

  1. HARPS3. ING has reached an agreement with the Cambridge-led THE (Terra-Hunting Experiment) Consortium for the deployment at the INT of HARPS3, 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 dates for the INT upgrade will be announced once the telescope upgrade project passes FDR. A six-month downtime period is planned for the upgrade. In view of the impact of Covid-19 on the project, telescope downtime for the upgrade is unlikely to take place during 2022.

  3. Instrument availability. Users may safely count that the WFC and IDS will remain available until telescope closure for upgrades (see above), i.e. at least up to and including 2022B. Both instruments will be decommissioned once the INT upgrade starts.

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