
Castor is a compact transformer-based coincident search pipeline for binary black hole gravitational-wave signals in Advanced LIGO data. It uses a Siamese architecture: the H1 and L1 detector streams are analyzed independently with shared transformer weights, producing per-detector detection statistics and frame-level merger-localization profiles.
The key practical advantage is scalable background estimation. Because Castor caches single-detector outputs, time-slide false-alarm-rate estimates can be generated by recombining those outputs rather than rerunning the neural network for each shift. This makes the pipeline well suited for low-latency and offline searches where robust empirical backgrounds are essential.
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| Fig. 1: Architecture of Castor. Shared transformer encoders process H1 and L1 strain streams, attention and frame heads produce detector-level summaries, and a post-hoc statistic combines them into a coincident ranking score. |
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