Detection of a Highly Circularly Polarized Pulse at S-band from LPT J1634+44

ATel #17440; Yunpeng Men (MPIfR), Ewan Barr (MPIfR), Gregory Desvignes (MPIfR), Ramesh Karuppusamy (MPIfR), Jason Wu (MPIfR)
on 10 Oct 2025; 16:03 UT
Credential Certification: Gregory Desvignes (gdesvignes.astro@gmail.com)

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We report on the detection of a highly circularly-polarized pulse from LPT J1634+44 at S-band. The observation was conducted with the Ultra-Broad-Band (UBB) receiver at Effelsberg on October 4, 2025. The time-of-arrival of the pulse is UTC 2025-10-04 17:09:25.6, which is phase-aligned with the timing solution reported in Dong et al. (2025, ApJ, 988, L29) and Bloot et al. (2025, A&A, 699, A341).

The pulse exhibits nearly 100% circular polarization, consistent with previous reports. The peak flux density of the pulse is estimated to be 0.3 Jy. The UBB receiver covers the frequency range between 1.3 and 6 GHz, but the pulse is detected only between 2.2 GHz and 3.0 GHz, as the other sub-bands are contaminated by strong Radio Frequency Interferences. The corresponding dynamic spectrum is shown in the link below.

A few days earlier, the CHIME/FRB and CHIME/Pulsar collaborations reported renewed activity from LPT J1634+44 at 400–800 MHz and L-band (ATel #17434). Combined with our observation, this confirms that the source is currently active up to S-band.

Spectrum of a pulse from LPT J1634+44 detected at Effelsberg