The GBM Accreting Pulsar Project detects pulsations from the HMXB J0440.9+4431 (LSV+44)
ATel #18067; Peter Jenke (UAH), Colleen Wilson-Hodge (NASA/MSFC), Christian Malacaria (INAF)
on 21 Sep 2026; 20:22 UT
Credential Certification: Peter Jenke (peter.a.jenke@nasa.gov)
Subjects: Binary, Neutron Star, Transient, Pulsar
The GBM Accreting Pulsar Project (GAPP) is detecting pulsations from the transient Be/X-ray binary RX J0440.9+4431 (LSV+44) starting September 17, 2026. The outburst, on September 19, 2026, reached a peak RMS pulsed flux in the 12-50 keV band of 0.325 +/- 0.018 keV cm-2 s-1 (72 mCrab). The measured frequency is 4.86126 +/- 0.00013 mHz. This outburst was first reported by MAXI/GSC Atel#18063 (Tian-Yu Liu, et al.) on Sep 20.
The GBM Accreting Pulsar Project
