ING can provide observations with non-standard requirements using the WEAVE LIFU mode only. Below we describe each case.

Targets of opportunity

A Target-of-Opportunity (ToO) programme is one for which observations of a rare or transient event are required at short notice, and they can be justified by the unique scientific opportunity these observations represent.

Starting in semester 2026A, the ING offers Target of Opportunity (ToO) observations using the LIFU mode. ToO proposals address unpredictable astronomical events that require immediate observation and whose timing does not align with the standard proposal preparation and OB submission cycle.

ToO proposals will be evaluated in the same way as regular Open Time proposals but will only be scheduled if they are ranked in the highest category Band A. Due to their disruptive nature, ToO observations will be capped at a maximum of 30% of the available Open Time for each national TAC.

The OBs will be prepared by ING following an activation trigger from the proposing team. The observing strategy at execution must match what was requested and approved in the proposal, and triggers must not exceed the allocated time.

At present, ING supports ‘next day’ triggers: for an event scheduled to be observed on a given night, the trigger must be received by the Observatory no later than 12:00 noon on the preceding day. ING will strive to execute ToO programmes on a shorter timescale on a best-effort basis.

PIs of ToO observations that can be anticipated at the semestral subsmision deadline for regular proposals, please refer to the latest announcement of opportunity for proposal submission.

Triggering teams of allocated programmes can submit their ToO requests using a phase-2 catalogue format, which ING will use to generate the observing blocks. The reduced observations will be available on the WEAVE Operational Repository.

ING Director's Discretionary Time

For observations of unanticipated ToOs of high scientific impact, the ING Director and the Head of Astronomy should be contacted with a brief science case justifying the need for the urgency, and the observations requested. Phase-2 preparation is similar to ToO observations above.

Time-critical and monitoring observations

Time-critical observations (at a certain time) and monitoring programmes (repeated observations over a period of time executed at a given cadence) are possible. Please specify this scheduling mode at phase 1. For discussion on feasibility and instructions on how to proceed, please contact for details:

Filler proposals

We encourage PIs to submit filler proposals. A filler proposal is one that it will be attempted under poor conditions, and hence, PIs of filler proposals should expect that their observations could be executed not necessarily in short time (proposal lifecycle is 3 years). These are the requirements for a proposal to be labelled as a filler proposal at phase 1:

• Only LIFU mode accepted.
• The position angle will be automatically set to a value such the brightest available guide star will be selected.
• It will be observed in conditions with OBSTEMP=XEFEG, equivalent to

  Seeing ≤3.0"
  Transparency ≥0.4
  Elevation: ≥25.0° (X≤2.4)
  Moon distance: Unconstrained
  Sky brightness: ≥17.7 V_mag/arcsec² (bright)

A Long-term programme is one that it requests time over several semesters to achieve the scientific goals of the proposal.

Community fibres (access to fibres not used in another observer or survey configuration) are likely to be offered (at least some of these, depending on demand) once the WEAVE observations are running smoothly.