The 2175 Å extinction feature in the optical afterglow spectrum of GRB 180325A at z=2.25

T. Zafar, K. E. Heintz, J. P. U. Fynbo +26

The UV extinction feature at 2175 Å is ubiquitously observed in the Galaxy but is rarely detected at high redshifts. Here we report the spectroscopic detection of the 2175 Å bump o…