Scheduling on the Low Frequency Array (LOFAR) Telescope

摘要

The newly built LOFAR telescope (www.lofar.org) is a multi-purpose sensor array. Its main application area is astronomy where it functions as a digital radio interferometer telescope at low frequencies (10-250 MHz). LOFAR currently consists of 24 core stations, 9 remote stations and 8 international stations that have been validated and are fully operational that are coupled together via a proprietary high speed optical network. The fast amount of data being produced runs up to 10 terabit per second. Via the optical network the generated data is sent to an IBM Blue Gene supercomputer where it is further processed. LOFAR has ten different antenna modes, is supporting multiple independent station beams, and is able to perform parallel observations observing multiple targets at once. Currently up to hundreds of observations per week are performed and this number is still increasing. Producing an observational schedule that fulfills all system and operational constraints with so many observations every week becomes a daunting task for a human. Because of the required flexibility and the wish to schedule as compact as possible an automated LOFAR Scheduler has been built. This LOFAR Scheduler software 'knows' all relevant system parameters and the software scheduling constraints of the LOFAR telescope. The LOFAR Scheduler is supporting the LOFAR telescope operators so that they are able to quickly choose between different observing strategies. The Scheduler also supports the operators by keeping track of the current status of the LOFAR hardware such as the stations and storage nodes and is able to quickly adapt the schedule if any of it fails.