[AAVSO-HEN] GRB090417B: optical observations

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  9140
SUBJECT: GRB090417B: optical observations
DATE:    09/04/18 00:23:39 GMT
FROM:    Johan U. Fynbo at U.Copenhagen  <jfynbo at astro.ku.dk>

J. P. U. Fynbo, D. Malesani, Jens Hjorth (DARK/NBI), E. Leitet, Staffan
Linne (Uppsala), Thomas A. Ottosen (NOT), P. Jakobsson (Univ. Iceland),
report on behalf of a larger collaboration:

We observed the field of GRB 090417B (Sbarufatti et al., GCN 9135) with
the NOT equipped with ALFOSC. Observations were carried out in the B, R
and i bands.

Inside the revised XRT error circle, we find a single source detected in
all three bands, with approximate magnitude R=21.3 (at mean time Apr
17.966, 7.84 hr after the GRB).

The source is also visible in the SDSS and classified as a galaxy.
Photometry reveals that the object has approximately the same brightness
as in the SDSS (in the R band). In the NOT images the object also appears
extended. The source is thus unlikely to be the afterglow of GRB 090417B,
although it may be its host galaxy.

We acknowledge excellent support from the NOT staff and observer.