Hosted Telescope Projects at ESO Sites

13th August 2018


ESO is hosting at its sites facilities which are provided and operated by funding agencies or institutes in ESO Member States to either extend the available capabilities or provide additional observing resources to a select community.

The ESO community does in general not have access to these telescopes. The operation is usually handled exclusively by the respective institutes. ESO welcomes such extensions to its programmes and has actively supported many telescopes on La Silla over the half century of its operation. More recently, projects have been hosted at Paranal as well.

The purpose of this document is thus to provide all interested parties with guidelines about the process to be followed, in order to have a project installed at one of the ESO sites. These guidelines have been approved by STC during its 84th meeting.


Hosted Telescope Projects are defined as projects which are built and operated without major ESO contributions but are hosted by ESO. They primarily cover scientific activities which are not pursued with ESO telescopes and can include public outreach and other activities.

Guidelines for Hosted Telescope Projects

Proposals for hosted projects should provide capabilities which are not available through ESO facilities, and they should be cost neutral to ESO.

ESO reserves the right not to accept proposals should the evaluation require significant ESO efforts, which impact on-going ESO activities and could lead to substantial overheads. This could also be the case should too many unsolicited proposals arrive within a short time frame.

Scientific evaluation by ESO

A panel selected by the Directors for Science and of Operations including several members of the STC evaluates all proposals for their scientific goals and impact. The evaluation includes a comparison with existing facilities, in particular ones already provided by ESO, an assessment of the scientific goals and expected results, and the importance the planned research has for astrophysics. An assessment of the scientific return to the ESO community is also performed, which also includes comments on the suitability of the site.

Technical evaluation

The Directorate of Operations, where necessary with the help of the Directorates of Programmes and Engineering, provides a technical assessment of the proposal. This includes an evaluation of the impact on site operations and potential changes in site infrastructure.

STC recommendation

The scientific and technical evaluations of the projects are presented to the STC for recommendation to the Director General.

General considerations

Member State proposals receive priority in cases of competition. ESO is the fiduciary owner of the telescope facilities while they are hosted on ES0 property.

All telescopes hosted on ES0 sites are subject to 10% Chilean observing time as stipulated in the 1995 supplementary agreement between ES0 and the Republic of Chile.

The hosting of telescope projects on ES0 property is regulated through a hosting agreement between ES0 and the respective institute. The layout of a typical agreement is inserted in Appendix A.

La Silla is the preferred site for visiting experiments. Proposals for telescope projects to be placed on other ESO sites need to present a compelling scientific case for this choice.

The role of La Silla as a scientific platform for such telescopes has been stressed in the La Silla 2006+ and La Silla 2010+ documents. The operational overheads at La Silla are currently minimal and the infrastructure is adequate for most expected facilities.

For major installations, it is expected that projects build their enclosures. Decommissioned ESO telescopes/domes/buildings are not made available for new projects, but they can be removed. After termination, projects are expected to clear the site, unless further usage can be envisaged. New projects shall re-use those existing sites and facilities which are in good conditions. A list of such sites is provided in Appendix B.

A. Layout of a hosting agreement

Before entering details, a description of the project, and a statement of interest of the two parties are introduced.

Article 1 – Installation and Operation

Here the hosting period is established (usually 5 years extendable), and the location within the site. The article includes the responsibility to remove facilities at end of contract.

It also defines the requirements on team members on site, who will be

  • under ESO’s authority
  • under ESO’s operation procedures
  • under ESO’s site safety regulations
  • self-insured

Article 2 - ESO Deliverables and Exclusions

Article 3 - Project Commitments

Intellectual Property

Data Access

Including availability to ESO community

Article 4 – Schedule and Termination

Article 5 - Costs and Payments

Article 6 – Liability and Miscellaneous

Article 7 – Jurisdiction and Arbitration Clause

Article 8 – Points of Contact


ANNEX A – The planned project installation at the Site

Description of items to be installed

ANNEX B – Map of the planned Project location at the Site

Map / drawings of planned installations

ANNEX C - Standard cost rates for ESO services

It includes:

  • Annual hosting fee
  • Labour costs for technical and maintenance support
  • Travel, board and lodging costs

ANNEX D – Jurisdiction and Arbitration

ANNEX E – Routing and Packing

Shipping, Import, Export and Customs procedures

Shipping instructions for overseas shipments

B. List of La Silla sites that are offered to potential projects