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GCN Circular 16770

GRB 140903A: P60 Optical Observations
2014-09-04T06:09:46Z (10 years ago)
S. Bradley Cenko at NASA/GSFC <>
S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) report on behalf of a larger collaboration:

We observed the field of the Swift short GRB 140903A (Cummings et al., GCN 16763) with the robotic Palomar 60 inch telescope.  Observations were obtained in the g', r', and i' filters beginning at 3:13 UT on 4 September 2014 (12.2 hr after the Swift trigger time).

We detect a faint source at the northern edge of the revised XRT error circle (De Pasquale et al., GCN 16767), with (J2000.0) coordinates

  RA: 15:52:03.28  Dec: +27:36:10.7

and an estimated uncertainty of ~ 0.5" in each coordinate. Visual comparison reveals that this is the same source identified by Capone et al. in the Discovery Channel Telescope imaging reported in GCN 16769.

Using nearby point sources from SDSS for calibration, we estimate a magnitude of r' = 20.0 for the source at this time.  We caution, however, that the photometry is strongly affected by the presence of the nearby bright star.  We estimate an uncertainty of ~ 0.5 mag, but accurate photometry will need to await a more thorough analysis.

Since our observations overlap with those reported by Capone et al., we cannot confirm any variability in this object.  Inspection of the archival SDSS images does not reveal an obvious source at this location, but the images are strongly affected by the nearby bright star, and thus the depth may be insufficient for a meaningful comparison.  We encourage additional follow-up to determine if this is indeed the optical afterglow of GRB 140903A.
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