{
  "bibcode": "2021GCN.31221....1M",
  "body": "D. B. Malesani (Univ. Radboud and DAWN/NBI), J. P. U. Fynbo (DAWN/NBI), \nA. de Ugarte Postigo (Obs. Cote d'Azur), L. Izzo (DARK/NBI), S. Fu, D. \nXu, Z. Zhu (NAOC/CAS), N. R. Tanvir (Univ. Leicester), A. A. Djupvik \n(NOT), report on behalf of a larger collaboration:\n\nWe observed the optical afterglow of GRB 211211A (D'Ai et al., GCN \n31202; Zheng & Filippenko, GCN 31203) using the Nordic Optical Telescope \n(NOT) equipped with the ALFOSC instrument. Images were secured in the \nSDSS r, g and i filters.\n\nAt the mean time of Dec 12.24 UT (16.6 hr after the GRB), we measure a \nmagnitude r = 20.89 +- 0.05 AB, calibrated against nearby stars from the \nPan-STARRS survey. Our measurement is in agreement with those by \nStrausbaugh & Cucchiara (GCN 31214) and de Ugarte Postigo et al. (GCN \n31218), taken at a comparable epoch. Compared to the magnitudes reported \nby Zheng & Filippenko (GCN 31203), Ito et al. (GCN 31217) and Jang (GCN \n31213), our data confirm the unusually slow decay,\n\nWe report for the afterglow the following coordinates (0.3\" uncertainty):\n\nRA = 14:09:10.12\nDec = +27:53:18.1\n\nA bright, extended object (r ~ 19.5) is visible about 5.5\" to the N-E of \nthe afterglow (as already pointed out by Zheng & Filippenko, GCN 31203), \nwhich is also visible in the SDSS, Pan-STARRS, and Legacy surveys.\n\nA spectrum was secured covering both the afterglow and the nearby galaxy \n(wavelength range 3700-9400 AA). A weak emission line is detected on top \nof the host galaxy trace at 7063 AA, which could be due to Halpha at z = \n0.076. This is marginally consistent with the SDSS photometric redshift \n0.140 +- 0.0375, unlike other interpretations of the same line.\n\nNo clear absorption or emission features are detected in the afterglow \ntrace. This may be due to the modest S/N, and is also consistent with a \nlow redshift, as is the detection of the afterglow in all the UVOT UV \nfilters (Swift observation ID 1088940000).\n\nIt is not clear at the present stage whether the afterglow is physically \nassociated with the galaxy at z = 0.076. While the sky proximity and the \nlow redshift are indeed suggestive, the physical offset at z = 0.076 \nwould be about 8 kpc (in projection), an unusually large value for long \nGRBs. There is also no visible emission in the archival images down to r \n~ 24 (AB) at the location of the afterglow, which would be unusual for a \nlong GRB at z = 0.076.\n\nMoreover, if placed at z = 0.076, GRB 211211A would be an outlier of the \nthe Amati relation (e.g. Nava et al. 2012, MNRAS, 421, 1256), with E_iso \n= 1.4*10^54 erg and E_peak ~ 700 keV (using the Fermi/GBM prompt \nproperties from Mangan et al., GCN 31210).\n\nOverall, a moderate-redshift GRB (with z > 0.076) is consistent with the \navailable information. The detection of an emerging supernova could \nclarify the situation. We encourage further photometric and \nspectroscopic follow-up of this potentially interesting event.",
  "circularId": 31221,
  "createdOn": 1639326296000,
  "email": "d.malesani@astro.ru.nl",
  "subject": "GRB 211211A: NOT optical spectroscopy",
  "submitter": "Daniele B Malesani at Radboud U  <d.malesani@astro.ru.nl>",
  "eventId": "GRB 211211A"
}