Documents released to the public have surfaced in Argentina regarding a UFO cover-up of a 1990s sighting in Antarctica, the country’s Ministry of Foreign Affairs has revealed.

Miguel Amaya, a former air force official, testified in the early 2000s that bizarre encounters occurred at the General San Martín military base, close to the South Pole.

The incident reportedly began around 1:15 a.m. on a mid-spring night in late April or early May 1991.

A laboratory alarm connected to an ionospheric monitoring instrument called a riometer suddenly activated, out of the blue. With his curiosity piqued, the engineer called the meteorological station to ask whether any radio equipment was transmitting.

According to Amaya, no transmissions were happening, making the signal even more eerie. Researchers then activated a graphic recorder that tracked ionospheric radio absorption with three needles.

At first, the instrument behaved normally, but minutes later, something bizarre happened. As Amaya recalled, “after five minutes, the three indicator needles began to make the same marks, which the engineer explained was impossible.”

Suspicious reading on the instruments

A riometer is a device that measures cosmic radio noise in the ionosphere – Earth's upper atmosphere – by tracking radio wave absorption at different frequencies.

Normally, each frequency produces a different pattern on the recorder. During the incident, however, the three needles began tracing identical patterns simultaneously.

The signal also appeared in intermittent bursts lasting 10-15 minutes. According to the witness, the fluctuations were intense enough to disrupt the recording system.

According to Amaya, “sometimes with such force that the needles would jump off the belt.” The anomaly reportedly lasted roughly 4.5 hours, generating dozens of meters of paper data.

A nuclear aircraft, perhaps?

Researchers struggled to find any natural explanation for the readings. According to the testimony, the engineer used an extreme comparison to describe the signal strength.

Amaya recalled him saying the readings were as if “the American aircraft carrier Kitty Hawk had been anchored ten meters from the house with its nuclear engines running.”

Another comparison suggested the equivalent of “a city like Buenos Aires suspended 100 meters above the ground.” At one point, the scientists even stepped outside with flashlights to check the sky.

They reportedly wondered if a UFO could be hovering above the base, causing the interference. The signal finally stopped around 5:30 a.m.

“Circle of light”

The strange measurements were not the only unusual event reported that day. Roughly 16 hours later, a member of the base allegedly saw something in the sky.

The witness had stepped outside during heavy snow and low clouds. According to Amaya’s testimony, the observer suddenly looked upward.

He reportedly saw “a huge circle of light, very dim due to the cloud cover.” The object appeared to move slowly and silently toward the sea. By the time others were alerted, the light had disappeared.

According to the account, the engineer reported the anomaly to his superior via radio the next day. The reaction reportedly halted further discussion.

Amaya said the supervisor responded: “There are some things that can’t be discussed over the radio.” The engineer was instructed to personally deliver the recording rolls months later.

Argentina has now confirmed that nine rolls of riometer data from 1991 still exist. The documents are currently stored at the Argentine Antarctic Institute.

Researchers say the newly released records could allow scientists to re-examine the unexplained atmospheric disturbance decades later.