GCN Circular 32177
Subject
GRB 220606B: Gemini South Optical Observations
Event
Date
2022-06-08T00:14:35Z (4 years ago)
From
Brendan O'Connor at UMD <oconnorb@umd.edu>
B. O'Connor (UMD/GWU), E. Troja (Tor Vergata), S. Dichiara (PSU),
on behalf of a larger collaboration:
We performed target of opportunity observations of the short
GRB 220606B (Fermi GBM Team GCN 32165, Tohuvavohu et al. GCN 32167)
with the Gemini Multi Object Spectrograph (GMOS) mounted on the
Gemini-South telescope. We obtained imaging in r-band and z-band
for 630 s in each filter starting at ~1.4 d post-trigger.
The GMOS field of view covers the central ~45% of the BAT error
circle (Tohuvavohu et al. GCN 32170). We note that this includes
a bright nearby galaxy with an estimated distance of 225 Mpc
(GLADE catalog; Dalya et al. 2016).
In comparison to the Dark Energy Survey DR2 catalog (Abbott et al.
2021), we do not identify any uncatalogued sources to a depth
r>25 AB mag and z>24.5 AB mag. This is in agreement with the
previously reported limit from Swift/UVOT (Evans et al. GCNs
32168 and 32173).
Our observations are sensitive to an AT2017gfo-like kilonova
at 225 Mpc. Therefore, either GRB 220606B is not physically
associated with the nearby galaxy or its kilonova is ~25 times
fainter than AT2017gfo at 1.4 d post-merger.
We thank the staff of the Gemini Observatory, in particular
Steve Margheim and Joan Font-Serra, for rapid scheduling of
these observations.