{
  "bibcode": "2000GCN...886....1V",
  "body": "P. Vreeswijk, E. Rol (U. of Amsterdam), C. Packham (U. of Florida),\nN. Tanvir (U. of Hertfordshire), C. Kouveliotou (MSFC/USRA), R. Wijers\n(SUNY) and J. Knapen (ING/U. of Hertfordshire), report on behalf of a\nlarger collaboration:\n\nWe observed the field of GRB 001109 [1] in J, H and Ks with INGRID on\nthe 4.2m William Herschel Telescope on La Palma, Canary Islands on\nNov. 9.8 and 11.8 UT, respectively 10 and 59 hours after the burst.\nThe 50\" radius error circle of the reported X-ray afterglow of \nGRB 001109 [2] is located at the center of our 4.2'x4.2' images.\n\nWe observed the UKIRT faint standard #30 [see 3] to calibrate the\nfield. The stellar FWHM in the co-added frames ranges from 0.9\" to\n1.3\" (pixelsize=0.25\").  The first table below shows the log of the\nobservations, including the estimated 3-sigma limiting magnitude\n(using an aperture diameter twice the size of the FWHM).\n\nAt the position of the radio source detected in the field [4], we\nobserve extended emission, consisting of a bright component (with a\nPSF FWHM significantly larger than that of point sources in the\nfield), and a fainter peak, separated by roughly 1\". The magnitudes\nthat we measure for this emission (using an aperture radius of 2.5\"),\nare also listed in the table. Within the errors (which do not include\nthe uncertainty in the calibration), this source does not vary. This\nconfirms the expectation [5] that the emission from this location is\nprobably not related to the GRB.\n\n\n         UT date   filter  exptime   lim. mag.  radio source\n -----------------------------------------------------------\n 2000 Nov.  9.81     J       300s      21.3\t18.64 (0.05)\n\t    9.80     H       750s      21.0\t17.96 (0.03)\n\t    9.79     Ks      750s      19.9\t16.96 (0.04)\n\n\t   11.86     J       600s      21.4\t18.70 (0.05)\n\t   11.82     H       600s      20.7\t17.93 (0.08)\n\t   11.83     Ks      600s      19.4\t17.07 (0.07)\n\n\nFurthermore, after close inspection of the images by eye and by\ncomparing the aperture magnitudes of all the detectable objects\nbetween the two epochs, we do not find an afterglow candidate.\n\nTo our knowledge, our images present the deepest near-infrared upper\nlimit on a GRB afterglow brightness to date. The table below shows all\nGRB afterglow near-IR detections and upper limits (that we could find)\nwith observations performed within 3 days of the burst occurrence.  It\nis clear that our early deep observations would have easily discovered\nany of the detections in the table, and that they are both earlier and\ndeeper than the reported upper limits. This result suggests that at\nleast some bursts are intrinsically faint in the near-IR and that the\ndust obscuration explanation for the GRB afterglow non-detections in\nthe optical may not be valid in all cases, unless this burst occurred\nat a redshift large enough for the optical/UV extinction in the rest\nframe to move into the K band regime in the observer's frame.\n\n\n GRB\t\tmagnitude\t       hrs. since burst\t    reference\n --------------------------------------------------------------------\n 971214\t\tJ=20.3\t\t\t     11\t\t      [6]\n 980329\t\tJ~19.2\t\t\t     16\t\t      [7]\n 980703\t\tH=17.6\t\t\t     30\t\t      [8]\n 990123\t\tK=18.3\t\t\t     29\t\t      [9]\n 990510\t\tJ=17.1, H=16.4, K=16.6\t     14\t\t      [10]\n 990705\t\tH=16.6\t\t \t      7\t\t      [11]\n 991216\t\tJ=16.8, K=15\t\t     13\t\t      [12]\n\t\tH=17.2\t\t\t     35\t\t      [13]\n 000214\t\tK>18.2\t\t\t     32\t\t      [14]\n 000301C\tK~17.4\t\t\t     50\t\t      [15]\n 000418\t\tK~17.5\t\t\t     60\t\t      [16]\n 000516\t\tJ>20.5, K>17.5\t\t     17\t\t      [17]\n 000615\t\tH>20.5\t\t\t     17\t\t      [18]\n 000926\t\tK~19\t\t\t     72\t\t      [19]\n\n\nFinally, we estimate a rough optical upper limit by extrapolating our\nH band upper limit to the R band, assuming a typical unreddened\nafterglow spectrum with a slope of -0.8, obtaining R > 23.1.\nExtinction intrinsic to the burster host galaxy is not included, which\ncan substantially increase this R band limit.\n\n References:\n\n 1. Piro, L. et al. 2000, GCN No. 879\n 2. Amati, L. et al. 2000, IAU Circ. 7519\n 3. http://www.jach.hawaii.edu/JACpublic/UKIRT/astronomy/calib/fs_newJHK.html\n 4. Taylor, G.B. et al. 2000, GCN No. 880\n 5. Stanek, K.Z. et al. 2000, GCN No. 881\n 6. Tanvir, N. et al. 1997, IAU Circ. 6796\n 7. Mannucci, F. et al. 1998, GCN No. 46\n 8. Vreeswijk, P. et al. 1999, ApJ, 523, 171\n 9. Bloom, J.S. et al. 1999, GCN No. 240\n10. Rol, E. et al. 2001, in prep.\n11. Masetti, N. et al. 2000, A&A, 354, 473\n12. Garnavich, P. et al. 2000, ApJ, 543, 61\n13. Rol, E. et al. 2001, in prep. \n14. Rhoads, J. et al. 2000, GCN No. 564\n15. Klose, S. et al. 2000, GCN No. 572\n16. Stecklum, B. et al. 2000, GCN No. 654\n17. Antonelli, A. et al. 2000, GCN No. 708\n18. Palazzi, E. et al. 2000, GCN No. 727\n19. Kobayashi, N. et al. 2000, GCN No. 821",
  "circularId": 886,
  "createdOn": 974495189000,
  "email": "pmv@astro.uva.nl",
  "subject": "GRB 001109: deep JHK upper limits",
  "submitter": "Paul Vreeswijk at U of Amsterdam  <pmv@astro.uva.nl>",
  "eventId": "GRB 001109"
}