//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8554 SUBJECT: GRB 081126: Swift detection of a burst DATE: 08/11/26 21:58:18 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT R. Margutti (Univ Bicocca&OAB), A. P. Beardmore (U Leicester), P. J. Brown (PSU), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), C. Guidorzi (INAF-OAB), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), J. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC), C. Pagani (PSU), P. Romano (INAF-IASFPA), M. Stamatikos (NASA/ORAU), T. N. Ukwatta (GSFC/GWU), L. Vetere (PSU) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team: At 21:34:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 081126 (trigger=335647). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 323.542, +48.709 which is RA(J2000) = 21h 34m 10s Dec(J2000) = +48d 42' 33" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a total duration of about 40 sec. The two peaks are about 30 seconds apart. The peak count rate was ~7000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 21:35:16.0 UT, 65.7 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source with an enhanced position: RA, Dec 323.5150, 48.7097 which is equivalent to: RA(J2000) = 21h 34m 3.60s Dec(J2000) = +48d 42' 34.9" with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 64 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 4.13e+21 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 7.07e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 75 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7' x 2.7' sub-image covers 100% of the XRT error circle. The estimated 3-sigma limiting magnitude is white > 21 mag. No correction has been made for the large, but uncertain extinction expected. There is a high proper motion 2MASS source inside the XRT error circle. Burst Advocate for this burst is R. Margutti (raffaella.margutti AT brera.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8555 SUBJECT: GRB 081126: TAROT Calern observatory optical observations DATE: 08/11/26 23:51:32 GMT FROM: Alain Klotz at CESR-CNRS Gendre B. (LAM-OAMP), Klotz, A. (CESR-OMP), Boer M. (OHP-OAMP), Atteia J.L. (LATT-OMP) report: We imaged the field of GRB 081126 detected by SWIFT (trigger 335647) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 20.6s after the GRB trigger (6.9s after the notice). The elevation of the field decreased from 41 degrees above horizon and weather conditions were very good. The date of trigger : t0 = 2008-11-26T21:34:10 The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect any OT at the XRT position (Margutti et al. 2008 GCNC 8554) with a limiting magnitude of: t0+20.6s to t0+80.6s : R > 16.6 The second image is 30.0s exposure in tracking mode: t0+86.7s to t0+116.7s : R > 18.0 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon= 92.9 lat= -2.3 and the galactic extinction in R band is 2.1 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8556 SUBJECT: GRB 081126: Enhanced Swift-XRT position DATE: 08/11/27 01:30:41 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 2152 s of XRT Photon Counting mode data and 1 UVOT images for GRB 081126, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 323.5147, +48.7098 which is equivalent to: RA (J2000): 21h 34m 3.54s Dec (J2000): +48d 42' 35.2" with an uncertainty of 1.8 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8557 SUBJECT: GRB 081126: Swift-BAT refined analysis DATE: 08/11/27 02:23:00 GMT FROM: Scott Barthelmy at NASA/GSFC G. Sato (ISAS), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), R. Margutti (U Bicocca&OAB), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-120 to T+183 sec from the recent telemetry downlink, we report further analysis of BAT GRB 081126 (trigger #335647) (Margutti, et al., GCN Circ. 8554). The BAT ground-calculated position is RA, Dec = 323.526, 48.714 deg, which is RA(J2000) = 21h 34m 06.3s Dec(J2000) = +48d 42' 51.0" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%. The mask-weighted light curve shows a small peak starting at ~T-30 sec, peaking at ~T-18 sec, and returning almost to zero at T-7 sec, at which time the second peak starts to rise. It peaks at ~T+1.5 sec and reachs a maximum at ~T+7 sec. The third peak peaks at ~T+31.5 sec and ends at ~T+100 sec. T90 (15-350 keV) is 54 +- 4 sec (estimated error including systematics). The time-averaged spectrum from T-21.4 to T+45.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.27 +- 0.06. The fluence in the 15-150 keV band is 3.3 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.75 sec in the 15-150 keV band is 3.7 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/335647/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8558 SUBJECT: GRB 081126: optical observations DATE: 08/11/27 02:54:03 GMT FROM: Alexei Pozanenko at IKI, Moscow Andreev M., Sergeev A., (Terskol Branch of Institute of Astronomy), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the field of GRB 081126 detected by SWIFT (trigger 335647, Margutti et al GCN8554 ) with the Z-600 telescope of Mt. Terskol observatory. A set of 90 s unfiltered exposures was taken starting (UT) Nov. 26 22:07:20. In a combined image of 3x90 s we detect a new object not presented in DSS2(R), in near vicinity to the object of USNO-A2.0 1350-14391154. A preliminary astrometry of the new object based on USNO-A2.0 is RA, Dec (J2000) = 21 34 03.56 +48 42 38.62 with uncertainty of 1", which is formally outside of enhanced XRT position (Osborne et al GCN 8556). It is not clear at this moment relation of the new object with GRB 081126. A combined image can be found at http://grb.rssi.ru/GRB081126/GRB081126_z600.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8559 SUBJECT: GRB 081126: Swift/UVOT Observations DATE: 08/11/27 02:58:03 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/GSFC/USRA) and R. Margutti (Univ Bicocca & OAB) report on the behalf of the Swift UVOT team: The Swift/UVOT observed the field of GRB 081126 starting 56 s after the BAT trigger (Margutti, et al. 2008, GCN Circ. 8554). Settled exposures started at T+75 s. We do not find any new source, relative to the DSS or 2MASS, or any variable source inside the UVOT-enhanced XRT error circle (Osborne, et al. 2008, GCN Circ. 8556). Preliminary 3-sigma upper limits for detecting a source in the co-added images, using a 2.5 arcsecond radius circular aperture, are Filter T_start T_stop Exp(s) Mag ------------------------------------------ white 75 225 147 >21.3 u 289 420 129 >20.1 v 5161 5361 197 >19.7 b 4546 6183 393 >20.9 u 3133 5976 326 >20.7 uvw1 5572 5771 197 >20.0 uvm2 5366 5566 197 >19.8 uvw2 4957 6398 199 >20.0 white 4751 6388 393 >21.8 ------------------------------------------ The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight corresponding to a reddening of E_{B-V} = 0.78 mag (Schlegel, et al., 1998, ApJS, 500, 525). All photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383, 627). The 2MASS point source 21340333+4842361 is located 3.2 arcsec north of the centre of the XRT error circle. Our photometry is slightly contaminated by an uncatalogued source approximately 2.6 arcsec northwest of the centre of the XRT error circle. This source appears to be extended and may be the host galaxy of GRB 081126. Preliminary magnitudes are Filter Mag Err ---------------------------------------- v 19.2 0.3 b 20.2 0.2 u >20.9 3-sigma upper limit uvw1 >20.1 3-sigma upper limit uvm2 >19.9 3-sigma upper limit uvw2 >20.1 3-sigma upper limit white 20.2 0.2 ---------------------------------------- The detection in the b filter, combined with the lack of a detections in the u and UV filters, is consistent with this source having a redshift of approximately 2.8 < z < 4.5. This corresponds to a physical separation of approximately 18 proper kpc assuming a cosmology with (H_0,Omega_matter,Omega_Lambda) = (70,0.3,0.7). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8561 SUBJECT: GRB 081126: Swift-XRT refined analysis DATE: 08/11/27 12:04:20 GMT FROM: Raffaella Margutti at U. di Milano Bicocca R. Margutti (Univ. Bicocca & INAF-OAB) reports on behalf of the Swift XRT team: We have analysed the first 5 orbits of Swift-XRT data obtained for GRB 081126 (Margutti et al., GCN Circ. 8554), covering 100 s of Windowed Timing (WT) and 9.1 ks of Photon Counting (PC) mode data, respectively, between 77 and 24 ks after the trigger. The UVOT-enhanced XRT position was given by Osborne et al. in GCN Circ. 8556. The light-curve can be modelled by a double broken power-law, with an initial decay of alpha_1= 1.2 +/- 0.2, a flat decay of alpha_2= 0.6 +/- 0.1 and a final value of alpha_3= 2.1 +/- 0.2. The two break times are around 200 and 9000 s, respectively. A spectrum extracted from WT data can be modelled with an absorbed power-law, with Gamma = 1.9 +/- 0.2 . A spectrum extracted from PC data in the time interval 3-30 ks post trigger can be modelled with an absorbed power-law, with Gamma = 2.0 +/- 0.1 and a column density of NH = (5.0 +/- 0.7)x10^21 cm^-2, which is compatible with the Galactic value in this direction (4.1x10^21 cm^-2). The observed (unabsorbed) 0.3 -10 keV flux over this time interval is 7.1x10^-12 (1.2x10^-11) erg cm^-2 s^-1. For both spectra there is no strong evidence for intrinsic NH. Uncertainties are given at 90% confidence. If the light-curve continues to decay with alpha ~ 2, the count rate 24 hours after the burst is estimated to be 2.7x10^-3 count s^-1, which corresponds to an observed flux of 1.4x10^-13 erg cm^-2 s^-1. The results of the xrt automatic analysis are available at http://www.swift.ac.uk/xrt_products/00335647. This is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8562 SUBJECT: Konus-Wind observation of GRB 081126 DATE: 08/11/27 14:52:48 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, D. Svinkin, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team report: The long GRB 081126 (Margutti et al., GCN 8554, Sato et al. GCN 8557) triggered Konus-Wind at T0=77649.857 s UT (21:34:09.857). The burst light curve shows a precursor at ~T0-20 s and two main pulse at ~T0-3 s and ~T0+28 s with a total duration of ~60 s. As observed by Konus-Wind the burst had a fluence of 9.91(-1.46, +1.57)x10^-6 erg/cm2, and a 256-ms peak flux measured from T0+1.808 s of (1.65 +/- 0.36)x10^-6 erg/cm2/s (both in the 20 keV - 2 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+41.216 s) is well fitted (in the 20 keV-2 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.82(-0.26, +0.32) , and Ep = 315(-71, +123) keV (chi2 = 68.0/61 dof). Fitting by GRBM (Band) model yields only an upper limit on the high energy photon index: beta < -2.16. All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB081126_T77649/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8564 SUBJECT: GRB 081126: Confirmation of the Optical Afterglow DATE: 08/11/27 15:56:19 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/GSFC/USRA), P. A. Evans (U Leicester), F. E. Marshall (NASA/GSFC), P. Schady (MSSL), and R. Margutti (U Bicocca & OAB) report on the behalf of the Swift UVOT team: We confirm the optical afterglow of GRB 081126 reported by Sergeev & Pozanenko (2008, GCN Circ. 8558). A re-examination of the UVOT data shows that there is a fading source at RA (J2000) 21:34:03.59 = 323.51496 (deg) Dec (J2000) +48:42:38.3 = +48.71064 (deg) with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence, statistical + systematic). This is consistent with the XRT error circle. Preliminary photometry and 3-sigma upper limits for this source are Filter T_start T_stop Exp(s) Mag Err ------------------------------------------------ white 75 225 147 18.82 0.09 u 289 420 127 18.17 0.13 v 5161 5361 197 19.29 0.32 b 4546 4746 197 20.20 0.28 u 5778 5976 197 >20.4 uvw1 5572 5771 197 >20.0 uvm2 5366 5566 197 >19.6 uvw2 4957 5156 197 >20.0 white 4751 4951 197 20.33 0.21 ------------------------------------------------ The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight corresponding to a reddening of E_{B-V} = 0.78 mag (Schlegel, et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). The detection in the u filter, combined with the lack of detections in the UV filters, is consistent with the afterglow having a redshift of approximately 2.4 < z < 3.8. However, this result is uncertain due to the large Galactic reddening along the line of sight to this source. The source identified in Holland & Margutti 2008, (GCN Circ. 8559) as being possibly extended is consistent with the catalogued position of the 2MASS point source 21340333+4842361. The separation between this 2MASS source and the afterglow is 3.2 arcsec. Since the photometry of the 2MASS source and the afterglow are consistent with both sources having at the same redshift it is possible that the 2MASS source is the host galaxy. Further observations are encouraged to confirm or reject this hypothesis. Holland & Margutti 2008, (GCN Circ. 8559) misidentified the optical afterglow as as the 2MASS point source 21340333+4842361. We apologize for any confusion caused by the misidentification in the previous UVOT Circular on GRB 081126. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8568 SUBJECT: GRB 081126: GRT Optical Observation DATE: 08/11/27 18:37:17 GMT FROM: Takanori Sakamoto at NASA/GSFC T. Sakamoto (UMBC/GSFC), Y. Urata (Saitama U), D. Donato (ORAU/GSFC), N. Gehrels (GSFC), T. Okajima (JHU/GSFC), T. N. Ukwatta (GWU/GSFC) We observed the field of GRB 081126 detected by Swift (trigger #335647) with the 14-inch Goddard Robotic Telescope (GRT) located at the Goddard Geophysical and Astronomical Observatory (http://cddisa.gsfc.nasa.gov/ggao/). Five set of 30s and 60s exposures were taken in the R filter starting from Nov. 27 03:58:18 (UT). We do not detect any OT at the XRT position (Osborne et al. 2008 GCNC 8556). The estimated 3-sigma upper limit of the combined image is ~17.5 mag using the USNO-B (r) catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8569 SUBJECT: GRB081126: Afterglow photometry from Crni Vrh DATE: 08/11/28 00:08:26 GMT FROM: Herman Mikuz at OCV J. Skvarc and H. Mikuz on behalf of PIKA observing program at Crni Vrh Observatory. We confirm variability of the source identified by Sergeev and Pozanenko (GCN Circ. 8558). The object was observed from Crni Vrh Observatory with a 60 cm telescope using R filter and a CCD in about 5 arc-second seeing conditions. First 60 s exposure started at 2008-11-26 21:35:32 UT. All twenty exposures were of 60 s. The table contains the time since the Swift GRB detection to the middle of exposure in seconds, R magnitude and formal 1-sigma magnitude error estimate. Time Mag Err. [s] [R] [1-sigma] ---------------------------------- 112.1 17.02 0.02 182.9 16.75 0.02 253.9 16.81 0.02 325.7 16.85 0.02 396.5 16.93 0.02 468.0 17.03 0.02 538.8 17.07 0.02 609.6 17.25 0.02 680.4 17.25 0.02 751.1 17.78 0.03 821.5 17.64 0.03 892.5 17.44 0.03 963.3 17.79 0.03 1034.3 17.79 0.03 1105.1 17.65 0.03 1176.8 17.76 0.03 1247.6 17.77 0.03 1318.5 17.71 0.03 1389.3 17.77 0.03 1460.0 18.50 0.05 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8570 SUBJECT: GRB 081126: Swift observations continuing DATE: 08/11/28 04:39:39 GMT FROM: Neil Gehrels at GSFC N. Gehrels (NASA-GSFC) on behalf of the Swift team Swift observations of GRB 081127 have been terminated in favor of the more interesting GRB 081126. The observations of GRB 081126 will continue through November 29 and possibly longer. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8587 SUBJECT: VLA Radio upper limit on GRB 081126 DATE: 08/12/01 16:57:26 GMT FROM: Poonam Chandra at U Virginia/NRAO Poonam Chandra (RMC) and Dale A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration: "We used the Very Large Array to observe the field of view toward optically bright GRB 081126 (GCN 8554) at a frequency of 8.46 GHz on 2008 Nov 28.97 UT. The GRB radio afterglow is undetected and the peak radio flux at the UVOT position (GCN 8564) is 24 ± 64 uJy. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8589 SUBJECT: GRB 081126: Fermi GBM detection DATE: 08/12/01 17:28:29 GMT FROM: Narayana Bhat at U Alabama/Huntsville/GBM P. N. Bhat (UAH) and A.J. van der Horst (NASA/ORAU) report on behalf of the Fermi GBM Team: "At 21:34:09.06 UT on 26th November 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB081126 (trigger 249428050 / 081126899) which was also detected by the SWIFT-BAT (Margutti et al. 2008, GCN Circular 8554) The angle from the Fermi LAT boresight is 18 degrees. This burst was also independently detected by INTEGRAL SPI-ACS and Konus/Wind (Golenetskii et al., 2008, GCN Circular 8562). The GBM light curve consists of two pulses separated by about 30 s with almost no emission in between. There is also a weak untriggered emission at about T0-20 s. The burst duration (T90) is about 56 s (8-1000 keV). The time-averaged spectrum of the first pulse from T0 s to T0+11 s is well fit by a Band function with Epeak = 192 +/- 74 keV, alpha = -0.3 +/- 0.4, and beta = -1.6 +/- 0.1.(chi squared 547 for 487 d.o.f.) Similarly the second pulse from about 20 s to 40 s is also well fit by a Band function with Epeak = 162 +/- 77 keV, alpha = -0.3 +/- 0.5, and beta = -1.6 +/- 0.1. (chi squared 539 for 487 d.o.f.). The time averaged spectrum of the entire burst is well fit by a Band function with Epeak = 176 +/- 84 keV, alpha = -0.3 +/- 0.5, and beta = -1.7 +/- 0.1. (chi squared 464 for 487 d.o.f.) The event fluences (8-1000 keV) in the two pulses are (2.7 +/- 0.8)E-07 erg/cm^2 and (1.9 +/- 0.8)E-07 erg/cm^2 respectively. The 1-sec peak photon fluxes in the 8-1000 keV band in the two pulses are 1.3+/- 0.4 ph/s/cm^2 and 1.0 +/- 0.4 ph/s/cm^2 respectively. The total event fluence (8-1000 keV) is (1.5 +/- 0.6)E-07 erg/cm^2. The 1-sec peak photon fluxes in the 8-1000 keV band in the two pulses are 0.7+/- 0.3 ph/s/cm^2 The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8590 SUBJECT: GRB 081126: afterglow photometry DATE: 08/12/01 21:39:02 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev, (Terskol Branch of Institute of Astronomy), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the field of GRB 081126 (Margutti et al GCN 8554) with the Z-600 telescope of Mt. Terskol observatory. Series of unfiltered exposures were taken between Nov.26 (UT) 21:48:45 - 22:34:35. A photometry of the afterglow (Andreev et al, GCN 8558, Holland et al, GCN 8564) against USNO-B1.0 (R2) field stars is following T0+ Exp. Mag. Err. mid s 940 10È15 18.6 0.2 1203 10x30 18.8 0.2 1635 5x90 19.3 0.3 2375 7x90 19.8 0.3 2920 5x90 20.1 0.3 The photometry is compatible with a power law decay of a light curve with index of ~ -0.66.