Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 9423

GRB 090518 - NOT upper limit
2009-05-26T07:21:31Z (15 years ago)
Johan U. Fynbo at U.Copenhagen <>
C. C. Thoene (INAF/OAB), E. Kankare (NOT), J. P. U. Fynbo, D. Malesani
(DARK/NBI), A. J. Levan (Univ. Warwick), P. Jakobsson (Univ. Iceland),
J. Hjorth (DARK/NBI) report:

We observed the field of GRB 090518 (GCN 9386, Evans et al.) with
ALFOSC/NOT on La Palma starting May 18, 20:54 UT (21 h after the burst).
Observations were obtained in R (3x300s), I (3x300s) and z (6x200s)
filters at high airmass.

We do not detect any new source at the XRT position (GCN 9387, Evans et
al.) in the summed image of each filter. The following upper limits were
obtained (based on USNO B1.0 reference stars and a NOT z-band archival

R > 23.7 mag
I > 21.8 mag
z(AB) > 22.5 mag
Looking for U.S. government information and services? Visit