VLT observations of GRB 990510 and its environment

We present BVRI photometry and spectrophotometry of GRB 990510 obtained wit h the ESO VLT/Antu telescope during the late decline phase. Between days 8 and 29 after the burst, the afterglow faded from R = 24.2 to similar to 26. 4. The spectral flux distribution and the light curve support the interpret ation of the afterglow as synchrotron emission from a jet. The light curve is consistent with the optical transient alone but an underlying SN with ma ximum brightness R > 27.4 or a galaxy with R > 27.6 (3-sigma upper limits) cannot be ruled out. To a 5-sigma detection threshold of R = 26.1, no galax y is found within 6 " of the transient. A very blue V similar or equal to 2 4.5 extended object which may qualify as a starburst galaxy is located 12 " SE, but at unknown redshift.