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GCN Circular 9338

GRB 090510: NOT afterglow confirmation
2009-05-10T10:30:19Z (15 years ago)
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <>
G. Olofsson, M. Ergon (Univ. Stockholm), D. Malesani, J.P.U. Fynbo 
(DARK/NBI), P. Jakobsson (Univ. Iceland), N.R. Tanvir, K. Wiersema 
(Univ. Leicester), A.J. Levan (Univ. Warwick), report on behalf of a 
larger collaboration:

We observed the field of short Swift/Fermi GRB 090510 (Hoversten et al., 
GCN 9331; Ohno & Pelassa, GCN 9334; Guiriec et al., GCN 9336) with the 
Nordic Optical Telescope equipped with ALFOSC. Observations were carried 
out in twilight and at high airmass (~3).

The candidate afterglow (Marshall & Hoversten, GCN 9332) is clearly 
detected in a stack of our images taken at a mean epoch May 10.215 UT 
(4.7 hr after the GRB). Calibrating against closeby USNO stars (R1 
magnitudes), we get R ~ 21.2. Comparing this value with the magnitude 
reported by Marshall & Hoversten (GCN 9332) indicates fading, thus 
confirming that this object is the afterglow of GRB 090510.

Astrometry of the field yields the following coordinates for the 
afterglow (0.4" error):

RA(J2000) = 22:14:12.64
Dec(J2000) = -26:35:02.8

which is consistent with the UVOT position. We note the presence of a 
fainter source ~1" East of the afterglow. A finding chart is posted at 
the following URL:

We acknowledge the observiers at the NOT for carrying out this difficult 

[GCN OPS NOTE(10may09): The authors point out that there is a correction
to the coordinates given above (see GCN Circ 9340).]
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