MeerCRAB: MeerLICHT Classification of Real and Bogus Transients using Deep Learning

TL;DR

MeerCRAB is a deep learning pipeline that effectively distinguishes real astrophysical transients from bogus detections in optical sky surveys, achieving high accuracy and integrating seamlessly into the MeerLICHT pipeline.

Contribution

This work introduces a novel deep learning pipeline, MeerCRAB, for classifying real and bogus transients, with innovative labeling methods and high accuracy.

Findings

Deep network achieved 99.5% accuracy.

High MCC value of 0.989 indicating strong classification performance.

Successfully integrated into the MeerLICHT pipeline for real-time transient vetting.

Abstract

Astronomers require efficient automated detection and classification pipelines when conducting large-scale surveys of the (optical) sky for variable and transient sources. Such pipelines are fundamentally important, as they permit rapid follow-up and analysis of those detections most likely to be of scientific value. We therefore present a deep learning pipeline based on the convolutional neural network architecture called $\texttt{MeerCRAB}$. It is designed to filter out the so called 'bogus' detections from true astrophysical sources in the transient detection pipeline of the MeerLICHT telescope. Optical candidates are described using a variety of 2D images and numerical features extracted from those images. The relationship between the input images and the target classes is unclear, since the ground truth is poorly defined and often the subject of debate. This makes it difficult to determine which source of information should be used to train a classification algorithm. We therefore used two methods for labelling our data (i) thresholding and (ii) latent class model approaches. We deployed variants of $\texttt{MeerCRAB}$ that employed different network architectures trained using different combinations of input images and training set choices, based on classification labels provided by volunteers. The deepest network worked best with an accuracy of 99.5$\%$ and Matthews correlation coefficient (MCC) value of 0.989. The best model was integrated to the MeerLICHT transient vetting pipeline, enabling the accurate and efficient classification of detected transients that allows researchers to select the most promising candidates for their research goals.