{
  "bibcode": "2013GCN.14669....1S",
  "body": "Vladimir V. Sokolov (SAO-RAS), Alberto J. Castro-Tirado (IAA-CSIC),\nAlexander S. Moskvitin, Elena A. Barsukova, Viktoria N. Komarova, Nikolaj\nV. Borisov, Azamat F. Valeev, Tatyana N. Sokolova (SAO-RAS) and Vitaly P.\nGoranskij (SAI-MSU, SAO-RAS), report:\n\n\"We have obtained 3 epochs of spectroscopy for the GRB 130427A optical\nafterglow (Maselli et al. GCNC 14448, Elenin et al. GCNC 14450) with the\n6-meter BTA equipped with Scorpio. The spectra (with exposure times of\n4 x 900 s, 5 x 900 s and 4 x 1200 s) were taken on May 2/3, 5/6 and\n10/11 respectively. We used the VPHG 550G grating which covers the\n3700-7900 A spectral range and provides a 13 A spectral resolution.\n\nNarrow host galaxy lines such as 3727 A [OII], [OIII] 4959 A, 5007 A and\nBalmer lines are noticeable in all spectra. The measured redshift is 0.3393,\nin good agreement with the previously reported values (Levan et al. GCNC\n14455; Xu et al. GCNC 14478; Flores et al. GCNC 14491; Garnavich GCNC 14605\nand Perley & Tang, GCNC 14615). Particularly, we detect marginal excess\nemission in the range 6000-7000 A on the later spectrum obtained on May\n10/11, which can be interpreted as evidence of the underlying SN (de\nUgarte Postigo et al., GCNC 14646), what is also supported by the\nlong-term photometric observations (Trotter et al., GCNC 14662; Watson et\nal., GCNC 14666).\n\nOur preliminary flux-calibrated spectra can be seen at:\n\nhttp://www.sao.ru/hq/grb/GRB130427A/GRB130427A_BTA_May2-10.jpg\n\nWe thanks S.N. Fabrika, O.P. Zhelenkova, Yu.Yu. Balega, V.V. Vlasyuk and\nA.S. Moiseev for their help in obtaining the observations.\"",
  "circularId": 14669,
  "createdOn": 1368739328000,
  "email": "ajct@iaa.es",
  "subject": "GRB 130427A:: BTA spectroscopic observations on May 10/11.",
  "submitter": "Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct@iaa.es>",
  "eventId": "GRB 130427A"
}