ASASSN-25cd: A Deep, Ongoing, Dipping Event
ATel #17211; B. JoHantgen, D. M. Rowan, K. Z. Stanek, C. S. Kochanek, J. Callahan, S. A. Petz (OSU), B. J. Shappee (Univ. of Hawaii)
on 29 May 2025; 16:21 UT
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)
Subjects: Optical, Variables
Using data from the All-Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014, Kochanek et al. 2017, Hart et al. 2023 ), we identified a star with a deep, ongoing, dimming event. ASASSN-25cd (RA = 18h31m52.78s, DEC = -28d48m27.14s, d ~ 2.1 kpc, G = 12.7, BP = 13.4, RP =11.9, DR3 source_id = 4048495409401002368) is a red giant star, likely a red clump star with a Gaia DR3 (Gaia Collaboration et al. 2023 ) extinction-corrected absolute magnitude M_G = 0.46 mag and color GBP -GRP = 1.11 mag.
This star was first observed by ASAS-SN on UT 2016-03-14 and it has roughly ~ 4,000 data points at this time. It had a mean g-magnitude of ~13.7 (V ~ 13.1) and no previous variability. The dimming event began around UT 2025-03-30. The star has faded by about 1.7 mag in the g-band and continues to fade by approximately 0.5 mag/month.
We thank Las Cumbres Observatory and its staff for their continued support of ASAS-SN. ASAS-SN operations are funded in part by the Gordon and Betty Moore Foundation through grants GBMF5490 and GBMF10501 to the Ohio State University, and Alfred P. Sloan Foundation grant G-2021-14192.
