ESO received 1285 valid proposals for observations in Period 117 (1 May 2026 – 30 April 2027). The deadline for proposal submission was 23 September 2025. On the VLT, the most demanded ESO instrument was ESPRESSO with a request of 5846 hours, followed by MUSE (5519 hours), and XSHOOTER (5086) hours. HARPS/NIRPS on the ESO 3.6 metre telescope was the most demanded instrument at La Silla, with a combined request of 4985 hours.
ESO Period 117 Proposal Submission Statistics
Published: 22 Oct 2025
In Paranal, the telescope with the highest oversubscription is Yepun (UT4), with a total request of 8402 hours, followed by Melipal (UT3; 8085 hours). Visitor Mode was requested by 11% of VLT programmes. This period ESO received 37 proposals for Large Programmes, 5 VLTI/I-ALMA joint proposals, and 4 VLTI/I-XMM joint proposals.
The distributed peer review (DPR) is evaluating proposals requesting a total telescope time below a certain threshold. Different thresholds were adopted to balance the panel workloads across scientific categories.
The Observing Programmes Committee and its Expert Panels evaluate 30% of submitted proposals in this Period, covering 76% of the total requested time. The rest of the proposals are being assessed by the DPR.
Proposing teams can expect to be informed of the outcome of the review process by February 2026.
The percentages of submitted proposals across science categories were:
- Cosmology and Intergalactic Medium 7%
- Galaxies 26%
- Interstellar Medium, Star Formation, and Planetary Systems 34%
- Stellar Evolution 33%