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GCN Circular 33671

Subject

GRB230420A: VLT optical observation

Date

2023-04-21T17:10:28Z (a year ago)

From

Hallie Fausey at George Washington U <hfausey@gwmail.gwu.edu>

H. Fausey (GWU), B. Schneider (MIT),  C. C. Thoene (ASU-CAS), D. B. Malesani (Radboud Univ. and DAWN/NBI), and S. Campana (INAF-OAB) report on behalf of the Stargate collaboration:

We observed the field of GRB230420A (Klinger et al., GCN33658GCN 33658
Jamie Kennea at Penn State U <jak51@psu.edu>
GRB 230420A: Swift detection of a burst
) with the ESO VLT UT3 (Melipal) using the acquisition camera of the X-shooter spectrograph. We took a 300s r-band image on 2023 April 20.105 UT (16 hours after the BAT trigger).

At the coordinates of the optical afterglow (Hu et al., GCN 33663GCN 33663
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
GRB 230420A: BOOTES-5/JGT optical afterglow detection
; Fu et al., GCN 33665GCN 33665
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
GRB 230420A: NOT optical afterglow confirmation
), we detect a faint source with magnitude r' = 23.2 +/- 0.1 (AB). The magnitude is consistent, within the errors, to the value reported by Fu et al. (GCN 33665GCN 33665
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
GRB 230420A: NOT optical afterglow confirmation
). We note the presence of a marginally-detected object in the Legacy Survey at the same coordinates, which, if real, could be the GRB host galaxy.

We acknowledge the excellent support from the ESO observing staff in Paranal, in particular Zahed Wahhaj.