AstroNote 2025-107

The BlackGEM consortium announces the discovery of BGEM J132554.96-430603.3 / AT2025guz. The transient is located 7' away from the center of the giant elliptical galaxy NGC 5128. It is detected three times in BlackGEM data taken between 2025-04-05 02:52:25 - 06:50:05 UT at an essentially constant brightness of q=20.15 +/- 0.15. No detections in the u- and i-bands are recorded with upper limits of u>19.1 and i>19.7. The latest non-detection in BlackGEM is from one day earlier, on 2025-04-04 05:59:41 with an upper limit of q>20.53. 

Follow-up observations are encouraged. 

The BlackGEM array is designed, built and operated by the BlackGEM Consortium, consisting of Radboud University, The Netherlands Research School for Astronomy (NOVA), the KU Leuven, Armagh Observatory and Planetarium, Durham University, the Hebrew University of Jerusalem, Las Cumbres Observatory, the Technical University of Denmark DTU, Tel Aviv University, Texas Tech University, the University of Barcelona, the University of California at Davis, the University of Hamburg, the University of Manchester, the University of Potsdam, the University of Valparaiso, the University of Warwick and the Weizmann Institute. The array is located at the La Silla Observatory of the European Southern Observatory in Chile.