GRB 110715A: Multiwavelength study of the first gamma-ray burst observed with ALMA

GRB 110715A had a bright afterglow that was obscured in the optical by a high Galactic extinction. We discovered the submillimeter counterpart with APEX and followed it in radio with ATCA for over 2 months. Additional submm observations were performed with ALMA as a test of the ToO procedures during commissioning, becoming the first GRB afterglow to be detected by the observatory. UV, optical and NIR observations were performed with Swift/UVOT and 2.2 m/GROND in La Silla and X-ray data were obtained by Swift/XRT. The dataset is complemented with spectroscopic data from the VLT/X-shooter spectrograph. The absorption features present in the intermediate resolution optical/nIR spectra reveal a redshift of 0.8224 and a host galaxy environment with low ionization. We fit in the host galaxy absorption features two velocity components separated by 30 km/s, implying a host galaxy with low dynamical activity. © EAS, EDP Sciences 2013.