The detection of OH 18 cm lines in C/2025 R3 with FAST

ATel #17744; 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 8 Apr 2026; 13:38 UT
Credential Certification: Tong Liu (tongliu@bao.ac.cn)

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Comet C/2025 R3 is a long-period comet that reached perihelion on April 19. We observed this comet with the ultra-wideband receiver of the Five-hundred-meter Aperture Spherical Telescope (FAST) on April 7 and 8, 2026. The integration time was set to 30 minutes on April 7 and 50 minutes on April 8, and OH 18 cm emission was successfully detected. The line-center velocities from two observations are -62.9 +/- 0.1 km/s and -63.5 +/- 0.1 km/s, respectively. For the observation on April 7, the integrated intensities at 1665 MHz transition and 1667 MHz transition are 1.6 +/- 0.1 K km/s and 3.2 +/- 0.1 K km/s, respectively. For the observation on April 8, the integrated intensities at 1665 MHz transition and 1667 MHz transition are 1.9 +/- 0.1 K km/s and 3.6 +/- 0.1 K km/s, respectively. See Figure 1 for details. The red solid line denotes the OH 1665 MHz transition, and the black solid line denotes the OH 1667 MHz transition. Additional follow-up observations will be performed.

The OH detection of comet C/2025 R3