Improving Astronomical Time-series Classification via Data Augmentation with Generative Adversarial Networks
This work addresses the challenge of rapid and automatic classification of millions of astronomical alerts per night for astronomers, though it is incremental as it builds on existing GAN methods with specific enhancements.
The paper tackles the problem of classifying astronomical time-series data with limited and imbalanced annotations by using Generative Adversarial Networks (GANs) for data augmentation, resulting in significantly improved classification accuracy for variable stars when tested on real data.
Due to the latest advances in technology, telescopes with significant sky coverage will produce millions of astronomical alerts per night that must be classified both rapidly and automatically. Currently, classification consists of supervised machine learning algorithms whose performance is limited by the number of existing annotations of astronomical objects and their highly imbalanced class distributions. In this work, we propose a data augmentation methodology based on Generative Adversarial Networks (GANs) to generate a variety of synthetic light curves from variable stars. Our novel contributions, consisting of a resampling technique and an evaluation metric, can assess the quality of generative models in unbalanced datasets and identify GAN-overfitting cases that the Fréchet Inception Distance does not reveal. We applied our proposed model to two datasets taken from the Catalina and Zwicky Transient Facility surveys. The classification accuracy of variable stars is improved significantly when training with synthetic data and testing with real data with respect to the case of using only real data.