Photometric Observations and Analysis of Active Asteroid (62412) 2000 SY178

Abstract The active asteroid (62412) 2000 SY178 is a C-type object located in the outer main belt and was first reported to exhibit a dust tail in 2014 May. Before and after its recent perihelion, we carried out long-term observations of 2000 SY178 with the Lijiang 2.4 m telescope between 2024 January 15 and 2025 May 13 to detect its activity and physical properties. In our research, the absolute magnitude was determined to be H = 14.02 ± 0.31 mag, which is consistent with the value of H = 14.07 ± 0.24 mag observed during the 2014 active event. Using this magnitude, we derived the effective radius of 2000 SY178 as r e = 3.95 ± 0.05 km. We modeled the light curves of 2000 SY178 with the Cellinoid shape model and derived its six axis ratios as a 1 = 1.0 ± 0.0000, a 2 = 1.3695 ± 0.0093, b 1 = 1.6748 ± 0.0076, b 2 = 1.6691 ± 0.0080, c 1 = 2.0267 ± 0.0093, and c 2 = 0.0324 ± 0.0023. Assuming 2000 SY178 is a strengthless rubble pile, its current rotation period of 3.328 hr exceeds the critical limit for rotational stability, suggesting that the observed activity 1is likely triggered by rotational destabilization.