On this page, we list the main changes that affected 4MOST and this web site.

Timeline of instrument status

The following table describes the events affecting the quality or the measurement of data obtained with 4MOST. Its content can be downloaded as a Comma Separated Values file.

This timeline is complete as of September 13th, 2020.

For each event, the Start Date column indicates when the event took place. Some events cannot be defined by a single instant, but extend over sometimes several days, weeks or months. Operation with the instrument may continue while the event occurs, in which case the Ongoing flag is set. If the event had ended, the Ongoing flag is lowered and End Date is given. The Type column indicates the characteristic(s) of the event: Earthquake, Maintenance, Upgrade, Element failure, Intervention, Pipeline installation at QC, Change of nominal values or thresholds, Modification of configuration file of this database, or Other. The Instrument Modes column indicates the affected mode. The column KPI lists the affected quality control parameters identified as Key Performance Indicators (i.e., parameters following the most critical quantities); the column non-KPI lists the other affected Quality Control parameters. The Calibration Raw Types column indicates the raw types of the affected calibrations. The Calibration Breakpoint flag indicates if calibrations obtained before the event cannot be used for science data obtained after the event or if calibration data obtained after the event cannot be used with science data obtained before the event. The Comment column provides more details on the event. The History column allows one to see possible past information on the entry.

The Quality Control pages for 4MOST can be accessed through the QC overview page.

Announcements

• 01 Nov 2025: 4MOST Commissioning starts. It will continue running until 31 Dec 2025.
• 18 Oct 2025: 4MOST First light! 
  
• 24 Sep 2025: 4MOST System Verification started at Paranal. Welcome 4MOST!