The NenuFAR “Virtual Control Room”

NenuFAR, an official pathfinder of SKA, is a new low-frequency radio array of 2000 antennas (crossed dipoles), in end of construction and start of operation at the Nançay Radio Observatory, France. It allows to observe according to several modes (beams, imaging, waveform…) associated to a large variety of setups. The instrument flexibility, added to its international use (12 key scientific programs active in the “Early Science” phase), motivated the development of a graphical control interface that is both powerful and easy to use. Based on Web technologies and accessible from various media (computer, smartphone, tablet), this interface called VCR (Virtual Control Room) allows the management of observations and monitoring of the telescope.

Via a simple web browser, the researcher can program and manage his.her observations within reserved areas (associated with access rights management, Fig. 1) defined via a semester schedule of the key programs. The sources to be observed are chosen among several astronomical catalogs online or via their coordinates, according to their visibility, and all the observation parameters are then defined (frequency band, receiver configuration, selection of mini-arrays, coupling to the LOFAR instrument, definition of different viewing directions, etc., Fig. 2). The observer can use predefined templates, modify some parameters, replay observations and access the quicklooks once the data has been recorded. An automatic verification system provides guidance throughout the process while ensuring configuration compliance with NenuFAR specifications.

The monitoring of the instrument and its radio environment is done in real time by visualizing low rate data (spectra). Housekeeping data from the telescope (temperatures, voltages, state of programs and servers, analog and digital subsystems) is ingested by relational (MySql type) and “time-series”oriented  (InfluxdB) databases. The use of specific software tools (Grafana, Telegraf, Chronograf) helps to supervise the entire telescope operation but also to visualize all the information needed for monitoring the instrument, and feeds an automatic alert system. Test observations, triggered automatically, guarantee efficient maintenance management. Visualization of the results on a map gives an instant overview of possible problems. A technician can then remotely modify the telescope’s configuration by activating or deactivating faulty elements until repair.

This web application results from the combined experience of the engineers of Nançay Radio Observatory and its associate astronomers, who have been managing and operating the Observatory’s radio astronomy instruments for several decades. NenuFAR’s Virtual Control Room has become an indispensable tool both for the day-to-day management of the instrument and for its long-term reliability.

C. Taffoureau & A. Loh, for the project NenuFAR (http://nenufar.obs-nancay.fr).