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The WEAVE Open-Time Programme

1. Phase 1: Applying for WEAVE Open Time
2. Proposals that "Pre-empt/Replicate" the WEAVE Survey
3. Proposals for Non-Standard Scheduling Requirements
4. Phase 2: Observing Preparation
5. Observing Priority Bands
6. Observations Follow up
7. Data Availability
8. Data Ownership
9. Publication Policy of PI Data that "Preempts/Replicates" the WEAVE Survey
10. Acknowledgement in Publications

During the years of the WEAVE Surveys, some WEAVE time will be made available to the community, as described in the document "WHT time during the WEAVE survey years".

The WEAVE Open-Time (OT) Programme on the WHT in the WEAVE era is the fraction of observing time which is reserved for observations other than those of the WEAVE Survey. Below, we provide potential applicants to the WEAVE OT Programme with a summary of the relevant procedures and rules relating to applying for time, and the use of the resulting data. For queries, please email

1. Phase 1: Applying for WEAVE Open Time

Information about the expected performance of the instrument can be found on the WEAVE overview.

The responsibility for the allocation of WEAVE OT rests with the time-allocation committees (TACs). In the years of the WEAVE Surveys, astronomers can apply for WHT OT through four main channels: the three national TACs (ING UK PATT, NL PC and ES CAT) and the CCI TAC, who runs the international time programme of the Canarian Observatories (ITP).

The availability of nights for WEAVE OT will be announced in the standard 6-month TAC calls (see Applying for Telescope Time). WEAVE OT proposals have their own application form.

PIs employed or studying in, or affiliated with, a Dutch, Spanish or UK institution at the time of submission should submit their proposal/s to the Dutch (NL PC), Spanish (ES CAT) or UK (ING PATT) TAC respectively. A similar rule applies to PIs who are working at foreign institutions based in any of these three countries - they should submit their proposal/s to the TAC of the country in which they are based.

The NL PC cannot accept proposals submitted by PIs employed or studying in a country other than the Netherlands. The ING PATT and ES CAT can accept proposals submitted by PIs employed or studying in a country other than UK and Spain as long as the majority of the collaborators on the proposal are employed or studying in the UK or Spain respectively.

The NL PC, ES CAT and ING PATT can accept proposals from PIs employed or studying at the Isaac Newton Group of Telescopes at the time of submission.

ING will provide the entire ING communities with access to the entire northern sky throughout the year. There will not be separate nights devoted to surveys and to open time. Rather, the observing queue will be populated with all eligible observing blocks (OB), from surveys and from open time, hence any night may accommodate OBs from both.

2. Proposals that "Pre-empt/Replicate" the WEAVE Survey

Avoiding duplications with WEAVE Survey science is understood to be desirable but complicated in practice, given the sheer size of the surveys. Therefore, neither the ING nor the WEAVE Survey Executive will aim at preventing principal investigator (PI) projects from pre-empting or replicating science from the WEAVE Surveys.

After proposal submission, the WEAVE Survey Executive will flag what constitutes pre-emption or replication of WEAVE Survey data, with the ING Director deciding over any disputes. See sections on Data Ownership and Publication Policy below for further details.

3. Proposals for Non-Standard Scheduling Requirements

Non-standard scheduling requirements (e.g. ToO observations, other time-critical observations) will not be catered for during at least the first year of WEAVE observing. However, given the potentially high scientific impact of such observations, it's likely that at some point in the future these will be possible.

Time-critical observations, monitoring programmes, long-term programmes and 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 Surveys are running smoothly.

4. Phase 2: Observing Preparation

OT programmes with WEAVE will always be done in queue service mode, and oObservations are detailed in XML observing blocks (OBs) which are prepared by applicants at WEAVE-OT Phase 2.

For phase 2, the awarded applicants will make extensive use of the

hosted at the Cambridge Astronomy Survey Unit (CASU), with support from the ING Astronomy Group as well as from CASU.

Communication between WASP and the principal investigator (PI) of the awarded proposal is established at the beginning of phase 2. A first email contains the necessary credentials to log on to WASP.

Every semester CASU provides two windows for phase-2 submissions which correspond to every trimester. For instance, PIs of proposals submitted for observing in semester 24A, will receive a call for submitting OBs for trimester 24A2, and later on, trimester 24B1. WASP provides these two distinct OB submission windows per semester to allow programmes with a particular visibility or time constraint to submit OBs twice or the latest possible.

Nevertheless, PIs of open-time proposals will usually prefer to submit all their OBs for a given semester during the first submission window so the OBs can be on the observing queue at the beginning of the observing period (start of first trimester). There is no need to resubmit OBs already active in the queue, so please check the activation period (trimesters on queue) of your programme in the time allocations before submitting OBs.

When preparing phase-2 observations, the PI will be guided through the following steps:

  1. Creation by WASP of accounts to allow each approved project to access the WASP platform.
  2. Creation by the user of a target catalog in FITS format; upload for validation on WASP.
  3. Creation by the user of XML Observing Blocks (OBs) from the validated FITS catalogue.
  4. Upload for validation on WASP of all planned OBs.
  5. Selection by the user of uploaded OBs for observation.
Deadlines for the above are listed on WASP trimester timelines (log on WASP first using your credentials). Once the above steps are complete, CASU sends the OBs to ING for ingestion into the observing queues at the beginning of the observing period.

Please email

for queries about the phase-2 process, or for assistance in preparing the FITS catalogue, the XML OBs and carrying out validations on WASP.

Specific information for applicants preparing phase-2 observations can be found at:

5. Observing Priority Bands

Effective time is defined as the time allocation made available to a time allocation committee after subtracting the average weather downtime and the foreseen maximum technical downtime. A time awarded proposal can lie in one of the following observing bands:

A-band proposals have very high priority. If an A-band proposal remains unfinished at the end of the applied semester, it will be granted an extended life-time over a number of additional semesters, or until its completion, whichever comes first. Unfinished A-band proposals do not have to be re-submitted in the additional semesters because of their carry-over status. A proposal is considered as complete when the quality of the obtained data meets the applied requirements.

B-band proposals have lower priority and they will be attempted only during the applied semester, after which they will be removed from the observing queue.

C-band proposals will be attempted only if no A- or B-band proposals can be observed. Therefore C-band proposals are unlikely of being observed yet they are queued. C-band proposals aren't carried over.

6. Observations Follow up

Progress on observations can be followed at the WEAVE Operational Repository, provided by CASU in Cambridge. User can log on using the same credentials used on WASP. Follow the link "Survey status" → "Observing blocks" for a follow up of your observations and data reduction.

7. Data Availability

Data-reduction and analysis of the observations are carried out automatically by the WEAVE pipelines at CASU and made available at the WEAVE Operational Repository (OR). From this platform users can search and download raw, L1-processed and L2-analysed data. Only the very latest versions of processed data are provided at the OR.

Eventually the raw and processed data are made available to the PIs through the WEAVE Archive (WAS).

Following the announcement made on 21st February, the OR is already open to users. Your login credentials for the OR are the same as you used for WASP when submitting your project OBs. If you do not remember your username/password combination for any reason, please send an email to:


Please do not try to reset the password yourself.

Comments and suggestions regarding the OR should be emailed to the above address. When reporting a problem with the OR please include a clear description of the action that resulted in the problem. Reports of any issues with L1 (CPS) or L2 (APS) data should mention the relevant filename and the values of the following parameters:

A detailed description of how the observations are processed and eventually released can be found in the WEAVE data model documentation:
  1. Login to WASP or the OR.
  2. Get to WEAVE data model ("Tools"-->"Data Model"): on WASP | on the OR.
  3. In section "Resources", click on the "Documentation" tab and download the "Science Processing and Analysis interface document" (WEAVE-ICD-027). The "WEAVE data product templates" tab provides a summary of all the available data products and FITS templates.
The WAS data availability page provides a description of how the data are made available to the PIs eventually.

Note: when inspecting LIFU observations, please note that the central fibre of the LIFU mode is fibreid="305" or ifu_spaxel="C14".

8. Data Ownership

As established in the WEAVE Data Policy, OT data are proprietary to the PI for one year after the Core Processing System (CPS)-reduced data are made available to the PI. The length of this period can be negotiated with the ING in extraordinary cases.

After the expiry of the proprietary period, WEAVE OT data are available world-wide in the WEAVE Archive System (WAS). By default, WEAVE OT data are processed by the WEAVE CPS and Advanced Processing System (APS) in the same way as WEAVE Survey data, and are ingested into the WAS where the PI can access raw, CPS-processed and APS-processed data.

However, OT data which pre-empt or replicate survey data will be flagged in the WAS in such a way that, in addition to the proposal's PI, WAS users with access rights to WEAVE Survey data will have access to these data as if it were WEAVE Survey data. Such data will not be released to the world after one year after reception by the PI but later, as part of the next WEAVE Survey data release.

9. Publication Policy of Data that "Preempts/Replicates" the WEAVE Survey

It follows an expansion of the WEAVE Publication Policy to cover publishing PI data that “preempts/replicates” the WEAVE Survey:
  1. If a Science Team or (group of) WEAVE Participant(s) decide that they want to use those data, they must invite the authors of the PI proposal to collaborate on the paper that the WEAVE Participants are writing based on those data.
  2. If the PI decide not to work with the WEAVE Participant(s), the WEAVE Participants may publish work based on or using these data after the PI data proprietary period has expired.
  3. Under any circumstance, the PIs are allowed to publish any papers based on their PI data during the proprietary period (without the involvement of the WEAVE Participants, if interest had been raised).
  4. If WEAVE Participants are involved in any papers based on the PI data during the proprietary period, those papers must conform to the WEAVE Publication Policy (e.g. the use of the WEAVE “Publication wiki”).

10. Acknowledgement in Publications

All WEAVE publications must include the standard WEAVE acknowledgement.

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Contact:  (WEAVE Open Time Support)
Last modified: 05 April 2024