SKYWATCH INCIDENT REPORT PRIMARY CODE: UNIDENTIFIED AERIAL PHENOMENON Date: 00:09 02/02/2023 Callsign: ASA18 Origin: PDX Status: Closed Aircraft: B739 Destination: JFK POD: DEN Tail Number: New Destination: Reporting Facility: HQ DEN Operator: ASA Operator Type: Commercial Paged: NO REMARKS Aircraft reported a balloon between FL400-FL450, off the left side while east bound at FL350, 10 NM SE of BIL. SKYWATCH INCIDENT REPORT | DATE: 2023-02-02T00:09 | POD: DEN | PAGE 1 of 1