We report on the follow-up of the extremely bright long gamma-ray burst GRB~210619B with optical polarimetry. We conducted optopolarimetric observations of the optical afterglow of GRB~210619B in the SDSS-r band in the time window ~ 5967 - 8245 seconds after the burst, using the RoboPol instrument at the Skinakas observatory. We report a 5σ detection of polarization P=1.5±0.3 at polarization angle EVPA=8±6∘. We find that during our observations the polarization is likely constant. These values are corrected for polarization induced by the interstellar medium of the Milky Way and host-induced polarization is likely negligible. Thus the polarization we quote is intrinsic to the GRB afterglow.
@article{arxiv.2208.13821,
title = {GRB 210619B optical afterglow polarization},
author = {N. Mandarakas and D. Blinov and D. R. Aguilera-Dena and S. Romanopoulos and V. Pavlidou and K. Tassis and J. Antoniadis and S. Kiehlmann and A. Lychoudis and L. F. Tsemperof Kataivatis},
journal= {arXiv preprint arXiv:2208.13821},
year = {2023}
}