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GCN Circular 8577

GRB 081128: Liverpool Telescope afterglow confirmation
2008-11-29T11:21:44Z (15 years ago)
Cristiano Guidorzi at INAF-OAB <>
C. Guidorzi (INAF-OAB), N. Tanvir (U. Leicester), I.A. Steele, R.J. Smith,
C.G. Mundell, D. Bersier (Liverpool JMU), A. Gomboc (U. Ljubljana)
report on behalf of a larger collaboration:

On 2008 November 28 (22:16:14 UT) we began observing the field of GRB 081128
(Margutti et al. GCN Circ. 8571) with the Liverpool Telescope.
Observations consisted of two sequences of 6x300s exposures acquired
using the SDSS-i and SDSS-r filters, respectively.

In our coadded frame we detect a single source inside the refined XRT
error box (Evans et al. GCN Circ. 8573) at the position
RA(J2000)=01:23:13.05, Dec(J2000)=+38:07:38.7 (0.6" error radius)
consistent with the optical candidate reported by Lin et al. (GCN Circ.
8575) and Andreev et al. (GCN Circ. 8576).
We found the following magnitude for this object:

Telescope   Filter  T_mid[hr]   Exposure[s]    M_lim
LT          SDSS-r    6.66        6x300        21.9 +/- 0.2

The calibration was performed using the R2 magnitudes of several USNOB-1
catalogue field objects. Compared with the value reported by Lin et al.
(GCN Circ. 8575), our measurement shows that the candidate has faded
between the two epochs.
There also appears to be a neighbouring source just outside the XRT
error circle, which might be a host galaxy.
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