Erratum to ATel #17662
ATel #17666; Margarita Pereyra (UNAM), Chao Wu (NAOC), Stephane Basa (UAR Pytheas), Z. Kang (CHO), William H. Lee (UNAM), J. Y. Wei (NAOC), Edilberto Aguilar-Ruiz (UNAM), Dalya Akl (NYUAD), Camila Angulo (UNAM), Sarah Antier (IJCLAB), Jean-Luc Atteia (IRAP), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), J. S. Deng (NAOC), Damien Dornic (CPPM), Jean-Gregoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo Garcia Garcia (UNAM), Ramandeep Gill (UNAM), Noemie Globus (UNAM), X. H. Han (NAOC), L. Huang (NAOC), Asuka Kuwata (UNAM), X. M. Lu (NAOC), Z. W. Li, Y. Lv (CHO), Nikos Mandarakas (LAM), Diego Lopez-Camara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Mendez (UNAM), Y. L. Qiu (NAOC), Ny Avo Rakotondrainibe (LAM), Fredd Sanchez Alvarez (UNAM), Benjamin Schneider (LAM), Damien Turpin (CEA-Irfu), Antonio de Ugarte Postigo (LAM), Alan M. Watson (UNAM), J. Wang, Y. J. Xiao, L. P. Xin , P. P. Zhang, R. S. Zhang (NAOC), report:
on 10 Feb 2026; 23:33 UT
Credential Certification: Margarita Pereyra (mpereyra@astro.unam.mx)
Subjects: Optical, Binary, Transient
In ATel #17662 we reported the presence of a short-timescale modulation with a characteristic timescale of approximately 1.35 hours in the optical light curve. We note that the original report did not include an estimate of the measurement uncertainty or a statistical justification of this timescale.
Based on preliminary Lomb-Scargle periodogram analyses applied independently to each of the four nights of Colibri r-band observations, we detect a statistically significant periodic modulation in each night. Period uncertainties were estimated using Monte Carlo simulations. The resulting periods are:
2026 Feb 6: P = 1.36 ± 0.01 hr
2026 Feb 7: P = 1.31 ± 0.01 hr
2026 Feb 8: P = 1.35 ± 0.01 hr
2026 Feb 9: P = 1.36 ± 0.01 hr
In all cases, the detected periodicity has a false-alarm probability <1e-3, indicating a highly significant detection against the null hypothesis of pure noise. We therefore characterize the signal as a quasi-periodic modulation with a characteristic timescale of P ≈ 1.35 ± 0.02 hours.
We note that a modulation on a comparable timescale is also present in the contemporaneous g, r, i, z, and y-band light curves, with similar morphology and phase coherence within each night, although a full multi-band period analysis has not yet been performed.
We also have a typographical error in the title. It should begin: ''COLIBRI and C-GFT detection ... ''
