{
  "bibcode": "1998GCN....31....1Z",
  "body": "S. V. Zharikov, V. V. Sokolov, SAO RAS and Yu. V. Baryshev,\nSt.Petersburg University report on behalf of the SAO RAS optical \nfollow-up team:\n\n\"Optical observations of the GRB 970508 optical remnant were continued\nwith the 6-m telescope of SAO RAS in the standard B, V, Rc, Ic bands\nin October-December 1997 and in January 1998.\n\nWe found:\nRc (UT Oct.09.94, 1997) = 24.30+/-0.20  (integ., 2100sec.)\nRc (UT Nov.10.04, 1997) = 24.70+/-0.15  (integ., 2400sec.)\nV  (UT Nov.10.04, 1997) = 25.10+/-0.17  (integ., 2700sec.)\nRc (UT Nov.25.97, 1997) = 24.70+/-0.14  (integ., 2500sec.)\nIc (UT Nov.25.99, 1997) = 23.90+/-0.14  (integ., 4800sec.)\nV  (UT Nov.26.06, 1997) = 25.50+/-0.35  (integ., 2100sec.)\nB  (UT Dec.01.91, 1997) = 25.75+/-0.30  (integ., 2400sec.)\nRc (UT Jan.24.87, 1998) = 24.96+/-0.17  (integ., 2580sec.)\nV  (UT Jan.24.87, 1998) = 25.44+/-0.25  (integ., 2400sec.)\nB band images have been obtained by A. I. Kopylov.\nIn determination of parameters of the faint host galaxy\nwe used the results of our BVRcIc photometry of May-August, 1997\n(see at http://xxx.lanl.gov/astro-ph/9802341),\nthe data of recent observations with Keck-II\n(Bloom et al., 1998, GCN Circular #30)\nand WHT telescopes (Castro-Tirado et al., IAU Circular No. 6848),\nand also the data of Rc and B bands photometry obtained\nby other authors based on our secondary standards:\nPedersen H.  et al., 1997, astro-ph/9710322;\nGarsia M.R., et al., 1997, astro-ph/9710346;\nGalama T.J.  et al., 1998, astro-ph/9802160.\n\nThe level-off from the initial power-law decline seen\nin the first months after the burst is observed in all bands.\nThe effect is the most strong in the Ic band: the difference at\nthe last date of Ic observations achieves ~1.3 mags. The best\nX^2-fits of the data in each of 4 bands point to the presence of a faint\nconstant source with \nIc = 24.13 +/- 0.28, Rc = 25.55 +/- 0.19, V = 25.80 +/- 0.14,\nB = 26.68 +/- 0.14. \n\nThe fitted magnitudes of the constant component\nand small angular size of underlying host galaxy\n(Pian et al. 1998, ApJ 492, L103)\ncorrespond to a dwarf elliptical galaxy with an absolute magnitude\nof M_B = -16.76 +/- 0.14 mags for z = 0.835\n(Metzger et al. 1997, Nature 387, 879).\n\nCorresponding figures for all 4 photemetrical bands can be seen in\nhttp://www.sao.ru/~zhar/home/GRB/970508.html\n\nThis message is quotable in publications.\"",
  "circularId": 31,
  "createdOn": 890950080000,
  "email": "sokolov@relay.sao.ru",
  "subject": "GRB970508 SAO RAS optical observations",
  "submitter": "V. V. Sokolov at SAO RAS  <sokolov@relay.sao.ru>",
  "eventId": "GRB 970508"
}