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GCN Circular 13986

GRB 121123A: NOT optical observations
2012-11-23T21:31:18Z (11 years ago)
Dong Xu at DARK/NBI <>
D. Xu, T. Kruehler, D. Malesani (DARK/NBI), G. Leloudas (OKC Stockholm
and DARK/NBI) I. Ilyin (AIP), J. Clasen (NOT), P. Jakobsson (U.
Iceland), J. P. U. Fynbo (DARK/NBI) report on behalf of a larger

We observed the field of GRB 121123A (Helder et al., GCN 13982) using
the 2.5m Nordic Optical Telescope (NOT) equipped with StanCam.
Observations started at 20:03:43 UT on 2012-11-23 (i.e., 9.972 hr
after the BAT trigger) and 5x300s R-band frames were obtained with
mid-time of 10.218 hr post-trigger.

The afterglow is clearly detected in the stacked image at coordinates

R.A.(J2000)= 20:29:16.289

with R=19.65+/-0.03 mag, calibrated with the #0781-0714632 star
(R1=R2=17.17 mag with a scatter of 0.3 mag) in the USNO B1 catalog.

We note that our measurement is only modestly fainter than the one
reported by Zhao et al. (GCN 13983) at 1.5 hr after the BAT trigger,
indicating a shallow decay or an irregular light curve.
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