W2C Payload

The Wide-field and Wide-band Camera (W2C) is eXTP’s high-energy transient monitor, designed to survey a large fraction of the sky and rapidly detect, localize, and trigger follow-up observations of the variable X-ray and gamma-ray Universe.

Operating as a coded-mask imager in the hard X-ray band, W2C complements the pointed SFA and PFA telescopes by detecting transient events as they occur. It will issue rapid alerts for gamma-ray bursts, magnetar bursts, accreting black-hole and neutron-star outbursts, and other high-energy transients, enabling autonomous eXTP repointing for detailed timing, spectroscopy, and polarimetry. W2C will therefore be a key component of eXTP’s time-domain and multi-messenger programme.

W2C uses GAGG scintillator detector arrays read out by silicon photomultipliers, based on the same detector unit (DU) design as CXBe. The University of Geneva will construct the W2C detector units and adapt the CXBe back-end electronics for W2C, establishing a common X-ray detection, readout, and control architecture for the two instruments.

The current baseline for W2C is configured at 48 DUs; however, depending on the availability of satellite platform resources (mainly the power budget), it can maximally be increased up to 88 DUs.