Detection of OH 18 cm lines in 3I/ATLAS with FAST
ATel #17733; Jiang D.(GZU), Qian L.(NAOC), Pan Z.(NAOC), Sun C.(NAOC), Yang Q.(NAOC), Huang M.(NAOC), Hao Q.(NAOC), Wang X.(NAOC), Guo M.(NAOC), Zhao L.(NAOC), Zhao Y.(NAOC), Jiang P.(NAOC)
on 31 Mar 2026; 08:02 UT
Credential Certification: Tong Liu (tongliu@bao.ac.cn)
We conducted observations of the third interstellar object to enter the Solar System, 3I/ATLAS, using the ultra-wideband receiver of the FAST telescope. The observation was done with the user-defined mode with a total integration time of 50 min per epoch. The observations were carried out on 2025 November 19 01:14-02:04, November 20 00:35-01:25, November 30 23:32-00:22, December 2 00:23-01:13, and December 3 23:06-23:56 (UT).
The absorption and emission were detected in the OH 1667 MHz line on November 19, December 1, and December 2. The corresponding line-of-sight velocities and integrated intensity are -22.6+/-0.3 km/s, -0.38+/-0.09 K km/s; -19.0+/-0.1 km/s, 0.19+/-0.05 K km/s; and -18.2+/-0.2 km/s, 0.41+/-0.09 K km/s, respectively. These values are consistent with the topocentric velocities -22.6 km/s, -18.9 km/s and -18.2 km/s, which derived from the JPL Horizons system.
The main OH 18 cm line profiles of 3I/ATLAS
