4MOST will obtain spectra of many different science cases simultaneously. Parallel observing enables efficient use of 4MOST for surveys that have complementary observing conditions requirements and/or a target density lower than the 4MOST multiplexing capability. It also implies that surveys have to agree on a common survey strategy and prepare Observation Blocks (OBs) jointly. As a consequence, all Participating Surveys have to fully share the raw data as well as the calibrated spectra in order to be able to assess and mitigate the impact of this cross-talk effect on their science. 4MOST operations have been designed to work within ESO’s La Silla-Paranal Observatory framework, with as few changes to infrastructure and processes as possible. Still, two main differences to the standard ESO science operations model are necessary: (1) a joint Science Team for all Participating Surveys (i.e. including Community Surveys as well as those from the instrument-building consortium); (2) common centralized tasks in observation preparation and data management provided as a service by the consortium.
Joint Operations Group
Coordination of the diverse group of stakeholders for 4MOST operations is ensured by the Joint Operations Group. The Joint Operations Group implements the scientific and operational guidance given by ESO, the Survey PIs, and the 4MOST PI. It contains representatives from the various work packages in operations. Its main task is to ensure observations progress with the best possible quality over the entire survey duration. Infrastructure Working Groups perform tasks common to all surveys. Their members are also members of the Science Team and are delegated to operations. Every Participating Survey is requested to provide resources to the Infrastructure Working Groups. The current working groups are: “Survey Strategy”, “Selection Functions”, “Galactic Pipeline”, “Extragalactic Pipeline”, and “Classification Pipeline”.
Science Data Flow for Participating Surveys
The data flow through the 4MOST facility (see figure below) will follow concepts that are familiar to most astronomers working with either ESO or large survey projects. In a nutshell, the following steps in the data and work flow are foreseen:
- Preparation of target catalogues with relevant associated data (e.g. Figure-of-Merit) by Surveys
- Submission of target catalogues to the Operations System
- Merging of catalogues and preparation of OBs by the Operations System
- Submission of OBs to ESO
- Execution of OBs at the VISTA telescope by ESO
- Transfer of raw data from telescope to the Data Management System
- Data reduction from raw data to calibrated spectra by the Level 1 pipeline of the Data Management System
- Transfer of Level 1 data to advanced pipelines
- Data analysis and creation of Level 2 data products by advanced pipelines
- Transfer of all data to archives
- Science exploitation by surveys and the world-wide community
Proposing community surveys wishing to use 4MOST in single survey mode are called Non-Participating Surveys. They will not become members of the Science Team, and will not be bound by the Science Team Policies. Their time will be allocated in named nights or half nights to enable accurate planning. The consortium Operations System will deliver the software necessary to produce OBs, which Non-Participating Surveys will run themselves. The consortium Data Management System will deliver Level 1 data products to Non-Participating Surveys through the Operational Repository. Non-participating surveys will not have access to the advanced pipelines developed in the 4MOST Science Team. Non-Participating Surveys will have to produce and upload their own Level 2 products to ESO.