SkyMapper optical follow-up of gravitational wave triggers: Alert science data pipeline and LIGO/Virgo O3 run
Abstract
We present an overview of the SkyMapper optical follow-up programme for gravitational-wave event triggers from the LIGO/Virgo observatories, which aims at identifying early GW170817-like kilonovae out to $∼200 Mpc$ distance. We describe our robotic facility for rapid transient follow-up, which can target most of the sky at $δ<+10\deg $ to a depth of $i_AB≈ 20 mag$ . We have implemented a new software pipeline to receive LIGO/Virgo alerts, schedule observations and examine the incoming real-time data stream for transient candidates. We adopt a real-bogus classifier using ensemble-based machine learning techniques, attaining high completeness ( $∼98%$ ) and purity ( $∼91%$ ) over our whole magnitude range. Applying further filtering to remove common image artefacts and known sources of transients, such as asteroids and variable stars, reduces the number of candidates by a factor of more than 10. We demonstrate the system performance with data obtained for GW190425, a binary neutron star merger detected during the LIGO/Virgo O3 observing campaign. In time for the LIGO/Virgo O4 run, we will have deeper reference images allowing transient detection to $i_AB≈ 21 mag$.
- Publication:
-
Publications of the Astronomical Society of Australia
- Pub Date:
- May 2021
- DOI:
- 10.1017/pasa.2021.17
- arXiv:
- arXiv:2102.07353
- Bibcode:
- 2021PASA...38...24C
- Keywords:
-
- methods: data analysis;
- methods: statistical;
- transient detection;
- gravitational waves;
- neutron stars;
- Astrophysics - Instrumentation and Methods for Astrophysics
- E-Print:
- 13 pages, 6 figures, Accepted for publication in PASA