SkyMapper Optical Follow-up of Gravitational Wave Triggers: Alert Science Data Pipeline and LIGO/Virgo O3 Run. (arXiv:2102.07353v2 [astro-ph.IM] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Chang_S/0/1/0/all/0/1">Seo-Won Chang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Onken_C/0/1/0/all/0/1">Christopher A. Onken</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wolf_C/0/1/0/all/0/1">Christian Wolf</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Luvaul_L/0/1/0/all/0/1">Lance Luvaul</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moller_A/0/1/0/all/0/1">Anais Möller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Scalzo_R/0/1/0/all/0/1">Richard Scalzo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schmidt_B/0/1/0/all/0/1">Brian P. Schmidt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Scott_S/0/1/0/all/0/1">Susan M. Scott</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sura_N/0/1/0/all/0/1">Nikunj Sura</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yuan_F/0/1/0/all/0/1">Fang Yuan</a>
We present an overview of the SkyMapper optical follow-up program for
gravitational-wave event triggers from the LIGO/Virgo observatories, which aims
at identifying early GW170817-like kilonovae out to $sim 200$ Mpc distance. We
describe our robotic facility for rapid transient follow-up, which can target
most of the sky at $delta<+10deg $ to a depth of $i_mathrm{AB}approx 20$
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 ($sim$98%) and purity
($sim$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_mathrm{AB}approx $21 mag.
We present an overview of the SkyMapper optical follow-up program for
gravitational-wave event triggers from the LIGO/Virgo observatories, which aims
at identifying early GW170817-like kilonovae out to $sim 200$ Mpc distance. We
describe our robotic facility for rapid transient follow-up, which can target
most of the sky at $delta<+10deg $ to a depth of $i_mathrm{AB}approx 20$
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 ($sim$98%) and purity
($sim$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_mathrm{AB}approx $21 mag.
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