{"paper":{"title":"VLT spectroscopy of GRB 990510 and GRB 990712; probing the faint and bright end of the GRB host galaxy population","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"A. Fruchter, C. Kouveliotou, E. Palazzi, E. Pian, E.P.J. van den Heuvel, E. Rol, F. Frontera, F.V. Hessman, H. Nicklas, J. van Paradijs, K. Beuermann, K. Reinsch, L. Kaper, N. Masetti, P.M. Vreeswijk, R.A.M.J. Wijers, S. Savaglio, T.J. Galama","submitted_at":"2000-09-01T19:53:58Z","abstract_excerpt":"We present time-resolved optical spectroscopy of the afterglows of the gamma-ray bursts GRB 990510 and GRB 990712. Through the identification of several absorption lines in the first epoch GRB 990510 spectrum, we determine the redshift for this burst at z >= 1.619. No clear emission lines are detected. The strength of the MgI feature is indicative of a dense environment, most likely the host galaxy of GRB 990510. Although the host is extremely faint (V >~ 28), the GRB afterglow allows us to probe its interstellar medium and - in principle - to measure its metallicity. The optical spectrum of G"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/0009025","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}