GCN Circular 32144
Subject
GRB 220527A: VLT/X-shooter spectroscopic redshift
Date
2022-05-28T10:32:22Z (2 years ago)
From
Andrea Saccardi at Observatoire de Paris <andrea.saccardi@obspm.fr>
A. Saccardi (GEPI, Observatoire de Paris), L. Izzo��(DARK/NBI), and D. Xu (NAOC)
report on behalf of the��Stargate collaboration:
We observed the afterglow counterpart of GRB 220527A detected by Swift-XRT (B. Sbarufatti et al. GCN Circ. 32135) during the follow-up observations of the Fermi/LAT-detected burst GRB 220527A (E. Bissaldi et al. GCN Circ. 32131) using ��the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph.��
A spectrum was acquired covering the wavelength range 3000-21000 AA, and consisting of 4 exposures of 600 s each. The observation started at 06:19:10 UT on 2022-05-28 (0.88 days after the GRB detection by Fermi/GBM).
From the detection of several absorption lines, which we identified as due to Al III, Ni II, Fe II, Mn II, Mg II, Mg I, and Ca II we infer a redshift z=0.857, which is in agreement with the redshift reported by the NOT (D. Xu et al. GCN Circ. 32141). We note also the presence of a possible intervening absorber, through the identification of Mg II, at z=0.455 which coincides with the photometric redshift of a nearby source visible in the Pan-STARRS archival images.
We acknowledge excellent support from the ESO observing staff in Paranal, in particular Rob van Holstein (ESO fellow) and Felipe Gaete (Telescope operator).