We observed again the field of the Swift GRB 041223 (Tueller et al., GCN 2898; Burrows et al., GCN 2901), using the ESO-VLT at Paranal. Optical and NIR observations were performed under excellent conditions (seeing 0.4") during the night of 2004 Dec 24 (~1.5 days after the GRB). We clearly detect the candidate afterglow reported by Berger et al. (GCN 2902), for which we measure J = 20.43...Full Text

We have posted online the results of the analysis of the X-ray afterglow of GRB 041223 (Tueller et al., GCN 2898; Burrows et al., GCN 2901). Plots displaying the lightcurve and the spectrum can be seen at...Full Text

GRB 041223 (Tueller et al., GCN 2898) was a spectrally hard burst. Fits to the total Swift-BAT burst spectrum are consistent with a power law, with a photon index of 1.05-1.15....Full Text

We imaged the field of GRB 041223 (Tueller et al., GCN 2898; Burrows et al., GCN 2901) with the robotic 60-cm REM telescope located at La Silla, Chile. Observations were carried both in the NIR and in the optical, on 2004 Dec 24 from 02:37 UT to 03:11 UT (i.e. ~12 hours after the burst). REM was equipped with the REMIR near-IR camera (10x10 sq arcmin FoV, JHK filters) and the ROSS optical...Full Text

We observed the field of GRB 041223 (Tueller et al., GCN 2898; Burrows et al., GCN 2901) with the ESO-VLT-UT1 equipped with the ISAAC camera, starting on 2004 Dec 24.256 (~16 hours after the GRB). The observing conditions were good, with a seeing of 0.6". Twelve one-minute exposures were acquired in the J band, with a mean UT 24.261....Full Text

"We imaged the 7-arcmin radius error circle of GRB 041223 (GCN 2898) with the Swope 40-inch telescope at Las Campanas Observatory starting on December 24.185 UT (14.4 hours after the burst) in r-band for a total of 20 minutes. We find a new bright source not present in the DSS which is located at (J2000): ...Full Text

The Swift X-Ray Telescope (XRT) was pointed at GRB 041223 (GCN 2898, Tueller et al.) on 2004/12/23 at 18:43:59 UT for 1490 s, at 20:16:24.4s for 1600 s, and at 21:50:40 for 430 s. The spacecraft did not autonomously slew to the burst since automated slewing is not yet enabled and the XRT is in the midst of engineering measurements. The observation was performed as a Target of Opportunity...Full Text

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to Swift GRB 041223 (GCN 2898). A manual response was initiated at 18:27 UT, around 4.5 hours after the burst. We took 10 5-s exposures followed by 200 20-s exposures. The first images were taken during twilight, and all the images were taken with >90% moon illumination. The unfiltered images were calibrated...Full Text

At 14:06:18 UT, the Swift Burst Alert Telescope (BAT) triggered and located on-board GRB 041223. The spacecraft did not autonomously slew to the burst since automated slewing was not yet enabled....Full Text