The LOFAR Transients Pipeline

John D. Swinbank (1, 2) , Tim D. Staley (3) , Gijs J. Molenaar (1) , Evert Rol (1) , Antonia Rowlinson (4) , Bart Scheers (1) , Hanno Spreeuw , Martin E. Bell (4) , Jess W. Broderick (5, 6) , Dario Carbone (1) , Alexander J. van Der Horst (1) , Casey J. Law (7) , Michael Wise (2) , Rene P. Breton (8) , Yvette Cendes (2) , Stéphane Corbel (9, 10) , Jochen Eislöffel (11) , Heino Falcke (8) , Rob Fender (12) , Jean-Mathias Greissmeier (13, 9) , Jason W. T. Hessels (2) , Benjamin W. Stappers (14) , Adam J. Stewart (15) , Ralph A. M. J. Wijers (1) , Rudy Wijnands (1) , Philippe Zarka (16)

1 AI PANNEKOEK - Astronomical Institute Anton Pannekoek
2 Department of Astrophysical Sciences [Princeton]
3 Oxford Astrophysics
4 CSIRO - Commonwealth Scientific and Industrial Research Organisation [Canberra]
5 UHH - Universität Hamburg
6 University of Southampton
7 RAL - Berkeley Radio Astronomy Laboratory
8 ASTRON - Netherlands Institute for Radio Astronomy
9 USN - Unité Scientifique de la Station de Nançay
10 AIM (UMR_7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
11 TLS - Thüringer Landessternwarte Tautenburg
12 UGA UFRM - Université Grenoble Alpes - UFR Médecine
13 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
14 JBCA - Jodrell Bank Centre for Astrophysics
15 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
16 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique

Current and future astronomical survey facilities provide a remarkably rich opportunity for transient astronomy, combining unprecedented fields of view with high sensitivity and the ability to access previously unexplored wavelength regimes. This is particularly true of LOFAR, a recently-commissioned, low-frequency radio interferometer, based in the Netherlands and with stations across Europe. The identification of and response to transients is one of LOFAR's key science goals. However, the large data volumes which LOFAR produces, combined with the scientific requirement for rapid response, make automation essential. To support this, we have developed the LOFAR Transients Pipeline, or TraP. The TraP ingests multi-frequency image data from LOFAR or other instruments and searches it for transients and variables, providing automatic alerts of significant detections and populating a lightcurve database for further analysis by astronomers. Here, we discuss the scientific goals of the TraP and how it has been designed to meet them. We describe its implementation, including both the algorithms adopted to maximize performance as well as the development methodology used to ensure it is robust and reliable, particularly in the presence of artefacts typical of radio astronomy imaging. Finally, we report on a series of tests of the pipeline carried out using simulated LOFAR observations with a known population of transients.

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]; Instrumentation and Methods for Astrophysic [astro-ph.IM]

John D. Swinbank, Tim D. Staley, Gijs J. Molenaar, Evert Rol, Antonia Rowlinson, et al.. The LOFAR Transients Pipeline. Astronomy and Computing, 2015, 11 (Part A), pp.25-48. ⟨10.1016/j.ascom.2015.03.002⟩. ⟨insu-01178502⟩