TITLE:   GCN CIRCULAR
NUMBER:  7658
SUBJECT: GRB 080430 - multicolor observations of the afterglow
DATE:    08/05/01 21:03:39 GMT
FROM:    Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr  <cthoene@astro.ku.dk>

Christina C. Thoene (DARK), Johan P. U. Fynbo (DARK), Antonio de Ugarte
Postigo (ESO), D. Alexander Kann (TLS), Nicolaas E. Groeneboom, Øystein
Rudjord, Jostein R. Kristiansen (Univ. Oslo) and Tapio Purismo (NOT)
report:

We observed the afterglow (GCN 7646, Klotz et al.) of GRB 080430 (GCN
7647, Guidorzi et al.) with MOSCA at the NOT/La Palma on Apr. 30 starting
1.21h after the burst. Observations in UBVRI filters with exposure times
of 150s in each filter were acquired.
The afterglow is clearly detected in all bands and we derive the following
preliminary magnitudes based on the pre-burst SDSS calibrations (GCN 7649,
Cool et al.) and standard transformations between SDSS and Bessell
filters, times given are the start of the exposures.

t-t0(h)  band   mag
1.92     U         19.9 +- 0.2
1.74     B         19.8 +- 0.1
1.56     V         19.3 +- 0.1
1.21     R         19.0 +- 0.1
1.38     I           18.7 +- 0.1

The blue colors and the detection down to the U band are consistent with
the low redshift of that burst, z=0.767 as found by de Ugarte Postigo et
al. (GCN 7650) and Cucchiara et al. (GCN 7654).