Applications for Use of the VLT Visitor Focus

The Visitor Focus has been reserved to permit innovative observations by teams using stand-alone instruments, free from a substantial fraction of the requirements for fully automated VLT general use instruments. In addition, the Visitor Focus could provide a powerful scientific/technical test bench for new instrumental concepts, eventually to be incorporated later in VLT facility instruments. The set of guidelines on how to propose and carry out this type of observation is given below. For technical information concerning the interface between a Visitor Instrument and the VLT please follow this link. Note that the side port of NAOS could also hold a small visitor instrument.

Interested parties should contact the VLT Programme Scientist (J. Melnick), Instrumentation (A. Moorwood) and Paranal (A. Kaufer).

Guidelines for VLT Visitor Instruments

Scientific Requirements

Acceptable Visitor Instruments (VI) shall offer observational capabilities not covered by other VLT instruments, or a largely superior performance in at least one valuable and sufficiently extensive scientific application. A major advantage of a VI is the capability to react quickly to new scientific and/or technical opportunities. Speed shall be a major criterion for the selection of VIs.

Technical Requirements

VIs shall be fully stand-alone, complete instruments, including their own data acquisition and storage capabilities. VIs shall comply with the VLT standards for safety, the interface to the Nasmyth adapter/rotator, power and coolant supplies, and LAN connection. Detailed information is available here.

Operation Mode

VIs shall be operated exclusively in Visitor Mode. The use of Observation Blocks is optional.

Data Flow and Archiving

VI data shall not enter the VLT data flow system. The VI Team shall take care of storing the data[, with a copy delivered to ESO headquarters. If scientifically appropriate and technically feasible, data shall be made publicly accessible one year thereafter, following current regulations on proprietary periods].


Following its approval, the present document will be posted as an Announcement of Opportunity on the ESO WEB. Proposals for a visitor instrument may be submitted at any time by individual institutes in ESO member states and Chile, Consortia of such institutes or international Consortia led by an ESO member state institute.

Procedures for the Approval of VI Proposals

VI proposals shall be submitted to ESO where they will be evaluated scientifically, technically, and operationally. Proposals shall contain

The proposals along with their ESO evaluation will be presented jointly to the STC and OPC. The STC will give its recommendations concerning the scientific and technical value of the proposed VI. The OPC will give its recommendations concerning the number of VLT nights to be granted to the VI Team.

VI Contract

Following positive OPC and STC recommendations, a contract shall be negotiated and stipulated between ESO and the VI Team. The contract shall specify the performance requirements of the instrument, the periods during which it will be attached to the telescope, the operational procedures, as well as the number and distribution of the observing nights allocated to the VI Team. The VI Team shall be responsible for delivery, installation, commissioning and operation ofthe instrument, as well as for its dismounting from the VLT at the end of the contract. The contract may be extended by mutual agreement.

Development, design and construction of VIs

ESO shall, where applicable, be kept informed about the progress and status of the instrument during its design and construction phases, e.g. by participating in the design reviews. At the end of the commissioning, the instrument shall be accepted released for operation, upon verification that it meets the performance, safety and operational requirements specified in the contract.

Use of VIs

After acceptance release for operation the VI Team shall be entitled to use the instrument on the VLT for the amount of time specified in the contract. Any extra-time required for commissioning may be deducted from the scientific time.

If appropriate, VIs may also be offered to the community for specified periods of time via the regular Calls for Proposals. The implementation of this possibility will be subject to the positive recommendation of the OPC and STC, as well as of the operational feasibility as assessed by ESO. The corresponding VI proposals shall be evaluated by the OPC following the normal procedures.

Property of VIs

A VI remains property of the VI Team, unless differently agreed upon between ESO and the Team. In the case of transfer of property to ESO the Team is entitled to guaranteed observing nights the number of which shall be specified following the general ESO guidelines for this matter.