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GCN Circular 32957

GRB 221120A: LDT Optical Afterglow Candidate
2022-11-21T02:57:19Z (2 years ago)
Brendan O'Connor at UMD <>
B. O'Connor (UMD/GWU), I. Andreoni (UMD), S. B. Cenko (NASA/GSFC),
E. Troja (UTV/ASU), S. Dichiara (PSU), A. Kutyrev (NASA/GSFC),
S. Veilleux (UMD), J. Durbak (UMD), on behalf of a larger collaboration:

We performed target of opportunity observations of GRB 221120A
(Eyles-Ferris et al., GCN 32955) with the 4.3m Lowell Discovery
Telescope in Happy Jack, AZ. Observations began on October 21,
2022 at 01:32:08.76 UT corresponding to ~4 hr after the GRB.
We obtained 8x150 s exposures in r-band under good conditions.

At the North-East edge of the XRT localization we detect a faint
source with magnitude r~24.1 AB mag. The source position is:

RA, DEC (J2000) = 02:45:21.36, 43:14:34.9 +/- 0.5"

No other sources are detected within 5" of the GRB localization to
depth r>24.5 AB mag. At present we cannot evaluate whether this
source is the counterpart to GRB 221120A. These results are consistent
with previous upper limits (Swain et al., GCN 32956).

We note the presence of a nearby bright galaxy at an offset of
~16.5" from the center of the XRT localization (Eyles-Ferris et al.,
GCN 32955). The galaxy has a photometric redshift from SDSS of z~0.12.
At this redshift, the offset from the XRT position is ~37 kpc. The
probability of chance coincidence is Pcc<0.05. Therefore. this is a
plausible host galaxy of GRB221120A.

Magnitudes are calibrated against nearby SDSS stars.

These magnitudes are not corrected for Galactic interstellar
reddening E(B-V)~0.08 mag.

We thank the staff of the Lowell Observatory for assistance with these

Further observations are planned.
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