LEIA detected the X-ray afterglow of the brightest GRB 221009A


EP-WXT Pathfinder, also known as LEIA (Lobster Eye Imager for Astronomy), has performed one follow-up observation of GRB 221009A ~2.6 days after the Swift trigger (Dichiara et al., GCN 32632). The pointed observation was conducted from 2022-10-12T05:31:48 to 2022-10-12T05:51:39 with a net exposure of 1012 s. The X-ray afterglow of GRB 221009A is detected at a significance of 4.9 sigma.

Assuming an absorbed power-law model with a photon index of 2.0, a Galactic absorption of 5.4 x 1021 cm-2 (Willingale et al. 2013; GCN #32651), and an intrinsic absorption of 1.1 x 1022 cm-2 at a redshift of 0.151 (GCN #32648), the unabsorbed flux in the 0.5 - 4.0 keV band is (1.8+/-0.4) x 10-10 erg cm-s-1.

This is the first GRB detected with LEIA, and also the first GRB observed with a lobster eye X-ray telescope ever.

The preliminary image of GRB 221009A afterglow detected by EP-WXT Pathfinder LEIA with a net exposure of 1012s.

The preliminary results have been posted at GCN Circular as GCN Circular 32767. Click here for more EP/LEIA GCN Circulars.