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GCN Circular 6406

GRB 070419A, Deep LBT photometry
2007-05-10T22:17:25Z (17 years ago)
Peter Garnavich at U of Notre Dame <>
P. Garnavich (Notre Dame), X. Fan, (U Ariz), X. Dai, J. Prieto,
K. Z. Stanek (Ohio State), J. Hill (LBTO/UAz), J. Bechtold (U Ariz),
R. M. Wagner (LBTO/OSU), J. Rhoads (Ariz State) report:

The Large Binocular Telescope (LBT) imaged the position of the GRB 070419A
afterglow (Stamatikos et al, GCN 6302; Chornock et al. GCN 6304) with the
LBC-blue CCD camera (http// and 8.4-m SX mirror on
2007 April 23.15 (UT). Ten dithered, 200 second exposures were obtained
with the Sloan-r filter in 1.2" seeing. The combined image shows a faint
source at J2000 12:10:58.80  39:55:33.71 +/-0.2 arcsec which is coincident
with the Chornock et al. coordinates.

Assuming the star at RA = 182.73852, DEC = 39.93033 J2000 has a Sloan r
MODEL magnitude of 20.394 mag (Swan et al. GCN 6339; Cool et al. GCN
6318), we find the source at the position of the afterglow to be
r=24.75 +/- 0.18 mag at 3.7 days after the burst.

Observations less than an hour after the burst by Smith et al. (GCN 6315)
and Swan et al. (GCN 6339) compared with our photometry imply a power-law
decay index of 0.9+/-0.1 over nearly 4 days. This is consistent with the
initial decline index of 1.1 (Swan et al. GCN 6339) and suggests that
either no break in the light curve had occurred or the host galaxy is
contributing to the measured LBT flux.

The LBT image can be found at:

The LBT is an international collaboration among institutions in the
United States, Italy and Germany. The LBT Corporation partners are:
*  The University of Arizona on behalf of the Arizona university system
*  Istituto Nazionale di Astrofisica, Italy
*  LBT Beteiligungsgesellschaft, Germany, representing the Max Planck
Society, the Astrophysical Institute Potsdam, and Heidelberg University
*  The Ohio State University
*  The Research Corporation, on behalf of The University of Notre Dame,
University of Minnesota and University of Virginia

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