A small lunar swirl and its implications for the formation of the Reiner Gamma magnetic anomaly

•We study one of the smallest lunar magnetic anomalies using 9 Hz magnetometer data.•We use three different inversion methods to determine its magnetization.•We find its magnetization direction is nearly equal to that of the Reiner Gamma anomaly.•We infer that this anomaly and Reiner Gamma formed at the same time.•We infer these anomalies likely formed as an ejecta deposit magnetized by a dynamo field.