Applying for ESO observing time

The Call for Proposals for Period 114 has been announced (for observations between 1 October 2024 – 31 March 2025). 

Proposal deadline

Thursday 21 March 2024 at noon Central European Time (10pm Australian Eastern Daylight Time, 7pm Australian Western Standard Time).

Under the terms of the Strategic Partnership between ESO and Australia, Australian-based astronomers have access to the facilities of the La Silla and Paranal Observatories, specifically the:

  • 3.6-m telescope (3.6);

  • New Technology Telescope (NTT);

  • Very Large Telescope (VLT); and

  • Very Large Telescope Interferometer (VLTI).

Complete details on how to apply can be found at the P114 Call for Proposals web page. All applicants should consult the Call for Proposals document for Period 114, and are required to update their ESO User Portal accounts to submit or be on proposals.

Any questions about policies or the practical aspects of proposal preparation should be addressed to the ESO Observing Programmes Office, [email protected]. Applicants who may wish to seek advice on proposal or observing strategies, optimal choice of instrument, etc. are invited to contact AAL’s ESO Program Manager at [email protected].


What’s new in Period 114?

Applicants are strongly encouraged to review the expected changes in instrumentation offered and procedures for Period 114 given in Sec. 1.1 of the Call for Proposals. Among the items likely to be of most interest to the Australian community are:

  1. New Large Programme proposals accepted in P114: Large Programme proposals (those seeking >100 hrs over 1-4 Periods) are only accepted once per year during the Call for even-numbered Periods. Large Programmes can be requested to start either in the semester of the Call or in the subsequent semester (the following odd Period), but the programme can extend at most over four consecutive semesters from the semester of the Call (i.e., currently up to Period 117). ESO strives to execute Large Programmes over shorter periods of time (aiming at two semesters by default), while maintaining the ceiling of 30% of the observing time allocated to Large Programmes set by the ESO Council. Note that due to the current high demand on UT4 in the 9<RA<14h range, any new Large Programmes targeting this RA range with UT4 will not be accepted.
  2. Maximising your chances of being scheduled: In the interests of maximising their chances of being able to be scheduled even if highly ranked, applicants are strongly urged to consider the essential information provided in the Forecast of telescope pressure by telescope and by Right Ascension. Note that for UT3, the allocation for the top 20% of turbulence plus CLR sky conditions around RA 17h is overcommitted due to an ongoing approved LP. Proposal submissions should consider the limited availability of observing time under these specific conditions.
  3. Joint VLT/I-ALMA proposals: ESO has introduced a joint channel for scientific programmes requiring both VLT/I observations and ALMA observations. ESO may award a maximum of 50 hours of ALMA observing time on each of its arrays to Joint Proposals per year. Further details can be found on the Joint VLT/I-ALMA proposals page. ESO has confirmed that ALMA would always treat an Australian-led Joint VLT/I-ALMA proposal as “Open Skies”, regardless of whether they get their time allocated through ALMA’s own joint proposal process, or through a joint VLT/I allocation. If in doubt, users should contact the ALMA helpdesk.
  4. FORS2: The FORS2 Absolute Photometry (FAP) is being decommissioned in early 2024, which means that users from P114 onwards can no longer rely on the zeropoints and extinction coefficients to photometrically calibrate their data. The pipeline is currently being prepared to calibrate imaging data observed with the standard BVRI filters using Gaia synthetic photometry. ObsPrep will allow users to verify the availability of Gaia stars with synthetic photometry during Phase 1. If none are available, the user is expected to request additional standard star observations if needed, as part of their allocated observing time.
  5. ERIS: All originally planned ERIS modes are now fully commissioned and offered.
  6. ESPRESSO: the Laser Frequency Comb (LFC) for ESPRESSO has been fully operational since October 2022, and the LFC calibrations for different modes have been included in the daily calibration plan. Proposal requesting it for wavelength calibration are accepted, but the users must inform USD and clearly indicate the need for the LFC for their science. The instrument status is regularly updated in the ESPRESSO news webpage.
  7. VLTI-UT: After a first commissioning period of the Gravity+ AO (GPAO) in October 2024, VLTI-UT science operations will resume in November 2024 in Service Mode, and from January 2025 in Visitor Mode. In this first phase of the GPAO implementation, only the Natural Guide Star modes, with a limiting magnitude of V/R = 12.5, visible and infrared, will be offered. Please see the VLTI manual for details.
  8. Simultaneous usage of HARPS and NIRPS on the 3.6m: NIRPS is a near-infrared (974nm-1919nmm), high-resolution (up to R = 90,000), cross-dispersed fibre-fed spectrograph optimised for stability and designed for the detection and characterisation of exoplanets around late-type stars that started operation in P111. It can be used simultaneously with HARPS to collect spectra from 380nm to 1919nm (with a gap from 689nm to 974nm) in a single acquisition. Its ultimate goal is to reach a long-term stability of ≤ 1m/s, but for the first period of operation a more conservative value of 2-3 m/s is adopted. A Laser Frequency Comb for wavelength calibrations is expected to improve further the stability from Period 114 onwards. Users requesting to use both NIRPS and HARPS should select NIRPS instrument in P1 and declare the intention of using both instruments in the Special Remarks field of the proposal.
  9. Gravitational wave follow-up observations: The OPC approved a Large Programme to cover the period of the current science run of the gravitational wave detectors (advanced LIGO, VIRGO and KAGRA). This programme covers all potential electromagnetic follow-up observations possible with ESO facilities until the end of P114 and hence no proposals depending on gravitational wave triggers will be accepted. The proprietary time of the LP has been reduced to two months to enable early access to the community for any data collected of gravitational wave sources.

We remind applicants of the following important messages:

  • Distributed Peer Review: With effect from P110, ESO introduced a Distributed Peer Review (DPR) process for proposals requesting a total time (including overheads) of less than 16 hours, with the exception of proposals including at least one ToO run; proposals for Calibration Programmes; Joint proposals; and DDT proposals. All other proposals submitted for P114 will be reviewed in the usual way by the OPC and its sub-panels. PIs of proposals qualifying for DPR accept that their proposals are reviewed by ten peers who have also submitted proposals in P114, and consent to reviewing ten proposals submitted by their peers as laid out in the DPR rules and guidelines. The PI may elect to delegate the reviewer’s role to one of the co-Is listed in the proposal.
  • Visitor Mode: Requests for Visitor Mode observations may be submitted (and are encouraged for new users in particular) for P114, although any scheduled runs may need to be executed in Designated Visitor Mode instead for operational reasons. Direct Qantas services between Sydney and Santiago operate 3 times per week, as well as daily services on LATAM via Auckland, and direct LATAM services between Melbourne and Santiago 3 times per week. ESO will pay for the costs of one visiting observer per run, and may also cover the costs of an accompanying student.
  • Scientific keywords: Starting in P110, a new set of scientific keywords replaced the traditional 4 OPC categories. From the p1 interface users must select at least two keywords, and at most five keywords (ten for Large Programmes). The keywords must be selected in decreasing order of relevance (i.e., the first selected keyword is the most relevant).
  • Proposal anonymisation: Under the Dual-Anonymous Peer Review (DAPR) policy applicants must formulate the scientific rationales of their proposals following these anonymisation rules and examples, which includes a detailed description of the DAPR paradigm. Failure to abide by the DAPR rules may lead to the disqualification of the proposal.
Important Data Privacy Notice for all recent and intending Australian ESO applicants

ESO supplies AAL with telescope/instrument demand and time allocation data relating to Australian astronomers only. Australian ESO applicant data is used only for statistical purposes, and will only be published or made available to other third parties such as AAL member institutions, in aggregated and anonymised form. ESO’s data collection/use provisions are available on the AAL ESO Forum for reference. It may be necessary to use automated data matching from data provided to the Data Central Lens proposal database to confirm the identity of ESO applicants. Applicants may opt out of providing data for Australian statistical purposes (including those from P101-P109 inclusive) by contacting [email protected].