Documents / Official release
This is a case resolution report from the Department of Defense's All-domain Anomaly Resolution Office (AARO), dated 20 March 2025. It covers infrared video taken on April 26, 2013 by a U.S. Customs and Border Protection aircraft over Rafael Hernandez Airport near Aguadilla, Puerto Rico. AARO found with high confidence that the video shows two objects drifting at wind speed over land, not one object splitting or entering the ocean. It assessed with moderate confidence that they were sky lanterns.
6 UNCLASSIFIED UNCLASSIFIED Data Quality and Methodology AARO assesses that the sensor data associated with the encounter provides sufficiently detailed information to resolve this case with high confidence. AARO’s assessment is informed by reconstruction of the event using STK and Minimum Separation Vectors analysis. Sensor Effects and Limitations Thermal imaging can fail to differentiate a target object from the background when its thermal signature is virtually identical to the surrounding environment to be distinct, known as thermal crossover. When a sensor fails to discriminate a target from its environment, the object can seem to vanish or intermittently disappear and reappear.3 Several factors affected the objects’ IR signature, contributing to the perception that they entered the water or disappeared. • Thermal Crossover: This natural phenomenon reduces the effectiveness of thermal imaging systems in detecting the contrast between an object and its environment during and after a rapid temperature change, such as during sunrise and sunset. It can persist for up to two hours.4 On April 26, 2013, sunset occurred at 7:48 p.m. local time. The IR sensor recorded the event at 9:22 p.m. local time, within the two-hour window when thermal crossover can influence IR sensor return.5 • Sensor Distance: The aircraft’s distance from the objects nearly tripled during the observation period. Sensor fidelity degrades with increasing distance to a target, especially for objects of such small size. • Cloud Cover: Scattered clouds at 3,000 feet partially obscured the sensor's view. Cloud cover can intermittently reduce an object’s thermal contrast, similar to the loss of detection that can occur during thermal crossover.6 Intermittent sensor contact can make an object appear to flicker or disappear and reappear on thermal imaging systems. Alternative Hypotheses Anomalous Phenomena: During specific frames, the objects seem to pass behind a utility pole, indicating that they were at a much lower altitude and traveling much faster than would be typical for objects of this size. AARO employed pixel analysis to investigate this alternative and found that the objects did not pass behind the pole, ruling out anomalous performance characteristics. Pixel analysis alone cannot determine the objects’ altitude or trajectory, though it can set parameters for further analysis. Therefore, AARO used STK reconstruction to assess the objects' flight behavior and performance characteristics. The STK reconstruction demonstrates that the objects moved in a straight line at wind speed over land. Marine Birds: An AARO partner assessed that the objects traveled between 35 and 130 mph at an altitude between 300 and 900 feet. The partner suggested that the objects were a pair of marine birds that descended to the surface of the Atlantic Ocean but noted that poor data quality Page determined to be Unclassified Reviewed by Chief of Staff, AARO IAW FY24 NDAA, Section 1841(a)(1)(C) Date: 3/20/2025 010
Official release, from the nara collection. The PDF is mirrored here; the original link is above. 7 pages are in the text index: search them above, or from the library's search.