[vsnet-grb-info 7660] GRB 090423: NOT z-band limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9214
SUBJECT: GRB 090423: NOT z-band limit
DATE:    09/04/23 23:17:44 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at astro.ku.dk>

D. Malesani (DARK/NBI), H. Dahle, I. Skorbakk (ITA, Oslo), E. Wuyts 
(Univ. Chicago), P. Jakobsson (Univ. Iceland), J. P. U. Fynbo, J. Hjorth 
(DARK/NBI), report on behalf of a larger collaboration:

We observed the field of GRB 090423 (Krimm et al., GCN 9198) with the 
Nordic Optical Telescope equipped with the MOSCA camera. Observations 
were carried out using the SDSS z' filter, starting on Apr 23.874 UT 
(13.0 hr after the GRB trigger) and with a total exposure time of 1 hr.

At the position of the NIR candidate afterglow (Tanvir et al., GCN 9202; 
Levan et al., GCN 9206; Cucchiara et al., GCN 9209), we do not detect 
any source down to a limiting magnitude z(AB) > 23.7, calibrated using 
the SDSS catalog.

We acknowledge excellent support from the NOT visiting observers.