This page provides an overview of the instrumentation plans for the WHT and INT in 2025 - 2026.

WEAVE on the WHT

1. WEAVE. Regular science observations with the LIFU (integral-field) mode of the WEAVE multi-fibre spectrograph started in October 2023. After a long standdown (Sep 2024 - Jun 2025) to allow the spectrograph to be re-aligned by a team from NOVA, LIFU science observing, and commissioning of the MOS and mIFU modes, have resumed.

   Once the MOS mode of WEAVE has been 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 MOS modes and, later, the mIFU mode. The MOS science surveys are expected to begin in autumn 2025.

   The 2026A call for proposals invites observers to submit requests for open-time observations with LIFU (including, for the first time, limited target-of-opportunity observations).

   Open-time observations with MOS are not offered in the 2026A call, but once MOS mode is commissioned, ING may issue a special call for open-time proposals.

2. Time distribution and instrumentation in the WEAVE surveys era. With the start of WEAVE science operations, the WHT changes from being a classical observing telescope to a queue-driven operation, with a 70% / 30% split between surveys and open time, after provision is made for 5% ITP (international time).

   Given the complexity of mounting and dismounting WEAVE, other instrumentation (e.g. ISIS, ACAM) are not currently being offered. Observers can safely assume that WEAVE will be continuously mounted on the WHT for the coming 2 years. Discussion of some of the issues involved can be found in the 2019 WHT telescope time document.

3. Pipeline-processed WEAVE data. Preliminary data products for nearly all of the WEAVE science data taken to date are available to the proposing teams at the WEAVE Operational Repository at CASU.

   We remind users that the data provided in the WEAVE Operational Repository can be used for monitoring progress and for quality control, but may not be stable. Only data obtained from the WEAVE Archive System (WAS) can be considered safe for publication, but WAS has been tested only with LIFU L1 (CPS) and L2 (APS) data. For this reason, WAS is not yet fully operational. ING recommends that teams wanting to use data from the OR send an email to weave_open_time_support@ing.iac.es so that ING can check with CASU the current status of those data.

INT and HARPS3

1. HARPS3. The Cambridge-led THE (Terra-Hunting Experiment) Consortium is leading the construction and development of HARPS3 for deployment at the INT. HARPS3 is a high-resolution stabilised spectrograph which will conduct an unprecedented 10-year survey aimed at discovering Earth-mass planets. The THE Consortium is carrying out a full upgrade of the INT to allow for robotic operation. Approximately 60% of the INT time will be devoted to the THE survey, the remainder being available as open time (for robotic observations with HARPS3 for now) to be allocated by the TACs.

2. Timeline. The INT upgrade started in June 2024, and is now complete. HARPS3 will be installed in October 2025, with commissioning planned during the Autumn and first scientific light currently expected in Q1 2026.

3. HARPS3 open time. We expect to offer HARPS3 in open time in semester 2026A. A dedicated delta-call will be issued following successful commissioning and science verification of the instrument.

We welcome your questions, comments or requests for clarification. Please email Ruben Sanchez-Janssen, ING Director (director@ing.iac.es) or Chris Benn, ING Head of Astronomy (crb@ing.iac.es).