The Northern High Time Resolution Universe pulsar survey

II. Single-pulse search set-up and simulations

¹ Department of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands
² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
³ ASTRON, the Netherlands Institute for Radio Astronomy, Oude Hoogevensedijk 4, 7991 PD Dwingeloo, The Netherlands
⁴ Jodrell Bank Centre for Astrophysics, University of Manchester, Alan Turing Building, Oxford Road, Manchester M13 9PL, UK

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 16 September 2025
Accepted: 2 January 2026

Abstract

The High Time Resolution Universe (HTRU) survey is an all-sky survey looking for pulsars and other radio transients. We present a new single-pulse (SP) search pipeline tailored to the northern part of the HTRU survey collected with the 100 m Effelsberg Radio Telescope. In a selection of the data, synthetic SPs are injected with frequency-time structures resembling those of the detected fast radio burst population and processed by the pipeline to characterise its performance. Therefore, several new software toolkits have been developed (FRBfaker and RFIbye) to enable the injection of SPs with complex frequency-time structures and cope with the radio frequency interference (RFI) in the survey’s data. We describe the operation of these toolkits alongside the overall functionality of the SP pipeline. Qualification of the pipeline confirmed that it is ready to process all the HTRU-North data. Additionally, we determine the survey’s sensitivity to SPs, the impact of RFI thereon, the performance of the deep-learning classifier FETCH, and some insights that may be used to improve the pipeline’s performance in the future. Within the small data sample analysed, we detected 21 known pulsars and a rotating radio transient. In addition, eight faint SP trains that might originate from yet undiscovered neutron stars and 141 isolated SP candidates were discovered.