In-orbit anomaly and recovery of IXPE detector 2
The Imaging X-ray Polarimetry Explorer (IXPE) is a joint NASA-ASI mission launched in December 2021 to measure the linear polarization of celestial X-ray sources in the 2-8 keV energy range. The payload comprises three identical telescopes, each combining grazing-incidence X-ray optics with a focal-plane photoelectric polarimeter based on the Gas Pixel Detector technology. On 14 April 2025, the second detector experienced an anomaly that significantly altered the electrical behavior of the ASIC responsible for reading out the photoelectron track images. In this contribution, we describe the effect of the anomaly on the instrumental response and the actions taken to mitigate its effects and recover the scientific observations of the instrument.