FAST Discovery of a New Millisecond Pulsar Binary

ATel #18076; Hang Gong (NAOC), Shaoqiang Xi (IHEP), Caisong Liu (NAOC), Pei Wang (NAOC), Lingqi Meng (MPIfR), Chenchen Miao (QLNU), Jifeng Liu (NAOC), Zhen Cao (IHEP)
on 23 Sep 2026; 13:52 UT
Credential Certification: Hang Gong (ghang.naoc@gmail.com)

Tweet

We report the discovery of a new millisecond pulsar binary using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) [1]. The system was identified at a beam center of R.A. = 19h 01m 38.29s, Decl. = +06° 49′ 59.3″ (positional uncertainty ~1.5′) based on our observation conducted in January 2025. PSR J1901+0649 has a spin period of 3.46 ms and a dispersion measure (DM) of 204.2 pc cm^-3. Timing analysis of subsequent FAST observations using the ELL1 binary model [2] yields an orbital period of 14.35 days and a projected semi-major axis of 13.06 light seconds. Assuming a nominal pulsar mass of 1.35 Msun, we derive a minimum companion mass of 0.32 Msun, suggesting a white dwarf companion. Notably, the system lies in close projection to 1LHAASO J1902+0648 [3]; whether this alignment is physical or coincidental requires additional verification. Further timing observations are underway to better constrain the parameters of this system.

FAST is a Chinese national mega-science facility, built and operated by the National Astronomical Observatories, Chinese Academy of Sciences (NAOC). We appreciate all the members in the FAST team and Dr. Yang Zonglin for their support and assistance during the observations.

[1] Nan et al. 2011, IJMPD, 20, 989, 10.1142/S0218271811019335
[2] Lange et al. 2001, MNRAS, 10.1046/j.1365-8711.2001.04606.x
[3] Cao et al. 2024, ApJS, 10.3847/1538-4365/acfd29