Mistral says: The Carrington Event, a powerful geomagnetic storm that occurred in 1859, was detected and documented primarily through the following observations:

1. **Visual Observations of Auroras**: The event is named after Richard Carrington, an English astronomer who observed and reported an extremely intense white light flare from a large group of sunspots on September 1, 1859. Independently, another English astronomer, Richard Hodgson, also observed the flare. The auroras associated with this event were visible as far south as the Caribbean and as far north as Santiago, Chile. People in the northeastern United States could read newspapers at night by the aurora's light.

2. **Telegraph System Disruptions**: The Carrington Event is well-known for its impact on the telegraph system, which was the most advanced technological system at the time. Telegraph operators reported sparks leaping from their equipment, and some telegraph systems continued to send and receive messages even after being disconnected from their power sources, powered solely by the current induced by the geomagnetic storm.

3. **Magnetometer Readings**: Magnetometers, which measure the Earth's magnetic field, recorded significant disturbances during the event. For example, those at the Kew Observatory in the United Kingdom showed dramatic swings in the magnetic field.

4. **Ice Core Samples and Tree Rings**: While not real-time detection methods, subsequent analysis of ice core samples and tree rings has provided additional evidence of the Carrington Event. These records show a spike in certain isotopes that are associated with high-energy solar particles.

These observations and records helped scientists understand the magnitude and effects of the Carrington Event, making it one of the most famous space weather events in history.