Analysis of the activity of Halley Family Comet 12P/Pons–Brooks during December 11 to 15, 2023

Comets have multiple origins, among which Halley-type comets and long-period comets originate from the Oort Cloud. Compared with long-period comets, Halley-type comets have shorter orbital periods. Therefore, observational studies of Halley-type comets can provide more opportunities for studying the active evolution of Oort cloud objects. As a Halley-type comet, 12P/Pons–Brooks has returned four times since its discovery, and has been very active with frequent outbursts. In order to monitor the activity changes of 12P/Pons–Brooks, we used the 80cm high-precision telescope at the Yao’an Observatory of the Purple Mountain Observatory of the Chinese Academy of Sciences to conduct B, V , R broadband filter imaging observations of 12P/Pons–Brooks from December 11 to 15, 2023. The photometric results in R-band show that the A(0)f ρ value of 12P/Pons–Brooks on December 15, 2023 is 15169 cm, which has increased significantly compared with the previous few days. The morphological analysis reveals that there is an obvious jet inside the coma of 12P/Pons–Brooks on December 15. The change of A(0)f ρ with aperture also reflects that 12P/Pons–Brooks is in a non-steady-state outburst state on December 15. These characteristics all indicate that 12P/Pons–Brooks is in an outburst state on December 15, 2023.