TOUTLEMONDE (49) 31.10.2017

On 31 October 2017 at 00:55, a witness at Toutlemonde took advantage of a clear sky to watch the stars toward the east. The western sky was less visible because of the Moon's brightness and light from Cholet. Scanning the horizon roughly toward Maulévrier, the witness noticed a fairly bright white light in the east-southeast, flashing blue and red. After 5 minutes, the witness realized it had moved little or not at all and checked the SkyView Free smartphone app, which did not identify the point. Continuing to watch, the witness noticed vertical movement and occasional rapid, jerky movements along short straight paths. Attempts to photograph and film it with a smartphone were hampered by the low light: the point was difficult to see in the photographs. Twenty-five minutes later it was still visible, clearly higher than initially. The blue and red flashing continued throughout, and the white light was much brighter than the stars. Only 1 account was collected. The witness's location plan indicates a viewing azimuth close to 120°. A Stellarium reconstruction places Sirius in the east-southeast at azimuth 120° and elevation 4° at 00:55, when observation began, and azimuth 123° and elevation 6° at 01:10, when the photograph was taken. GEIPAN explains the app's failure to show Sirius as possible poor calibration or a slight mismatch between the phone's displayed view and the actual sky. Comparing the witness's photograph with the sky chart clearly places the UAP and Sirius at the same position relative to other stars; see the investigation notes. The source describes Sirius as the brightest star after the “shepherd's star,” Venus, and notes that it never rises very high at these latitudes. Its apparent color changes result from atmospheric turbulence. GEIPAN attributes the short, jerky movements to the autokinetic effect, a known perceptual phenomenon when a point of light is viewed in darkness. The slow upward movement over 30 minutes matches Sirius's actual apparent motion caused by Earth's rotation. GEIPAN classifies the case A: Sirius, identified with certainty.