//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11102 SUBJECT: GRB 100816A: Swift detection of a possibly short burst with optical afterglow DATE: 10/08/16 01:17:12 GMT FROM: David Palmer at LANL S. R. Oates (UCL-MSSL), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), J. M. Gelbord (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), O. M. Littlejohns (U Leicester), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), C. J. Saxton (UCL-MSSL), M. Stamatikos (OSU/NASA/GSFC) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team: At 00:37:51 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100816A (trigger=431764). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 351.740, +26.561 which is RA(J2000) = 23h 26m 58s Dec(J2000) = +26d 33' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single symmetric peak structure with a duration of about 2 sec. There is possible further activity at around T+80s. The peak count rate was ~13000 counts/sec (15-350 keV), at ~0.5 sec after the trigger. The XRT began observing the field at 00:39:14.2 UT, 82.8 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 351.7381, +26.5785 which is equivalent to: RA(J2000) = 23h 26m 57.15s Dec(J2000) = +26d 34' 42.6" with an uncertainty of 5.5 arcseconds (radius, 90% containment). This location is 63 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 150 seconds with the White filter starting 91 seconds after the BAT trigger. The refined UVOT position is RA (J2000) 23:26:57.56 Dec (J2000) 26:34:42.9 with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). This position is 5.5 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.00 with a 1-sigma error of about 0.03. No correction has been made for the expected extinction corresponding to E(B-V) of 0.09. There were no real-time GCN Notices on this burst because the block2world filter was still in place due to the earlier episode of the startracker loss-of-lock problem. The MOC had just gotten the startracker back to lock and BAT triggers restored when the trigger occurred. But the block2world had not yet been removed. BAT_POSITION and XRT_POSITION notices were manually generated and distributed. Burst Advocate for this burst is S. R. Oates (sro AT mssl.ucl.ac.uk). 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: 11103 SUBJECT: GRB 100816A: ROTSE-III Optical Limits DATE: 10/08/16 01:42:21 GMT FROM: Shashi Bhushan Pandey at ROTSE S. B. Pandey (U Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 100816A, possibly a short duration burst, (Swift trigger 431764; Oates, S. R., GCN 11102), producing images beginning 6.8 s after the GCN notice time. An automated response took the first image at 01:00:05.7 UT, 1334.3 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 10 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going. Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle or the XRT error circle. Individual images have limiting magnitudes ranging from 16.2-17.9; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:00:05.8 01:00:10.8 5 16.6 1334.4 N 01:01:37.27 01:05:58.67 180 18.5 1534.4 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11104 SUBJECT: GRB100816A: TNG optical afterglow confirmation. DATE: 10/08/16 06:28:22 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma L. A. Antonelli (INAF-OAR), A. Fiorenzano (INAF-TNG), G. Tessicini (INAF-TNG), A. Stamerra (UniPisa) on behalf of the CIBO collaboration report: We observed the field of the short hard GRB100816A (Swift trigger 431764; Oates et al., GCN 11102) with the Italian 3.6m TNG telescope (La Palma, Canary Islands) equipped with the DOLORES camera. Observations started on Aug 16 at 03:22 UT (~2.8 hrs after the burst) under very poor weather conditions (high cloudiness and high humidity). We acquired a R band image of the GRB field for a total exposure time of 180s. We clearly detect a source consistent with the one reported by (Oates et al., GCN 11102). This souce, located at RA (J2000)=23:26:57.58; Dec(J2000)=+26:34:42.7 (+/-0.5''), showed a magnitude R~20.5 (calibrated against USNO B1.0) at the epoch of the observation. Due to its fading behavior with respect to the UVOT observation, we confirm that this source is the optical afterglow of GRB100816A. This message can be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11105 SUBJECT: GRB 100816A: MASTER Optical Limits DATE: 10/08/16 12:00:01 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina, D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka K.Ivanov, S.Yazev, N.M.Budnev, E.Konstantinov, V.Lenok, O.Gres, O.Chuvalaev Irkutsk State University MASTER robotic telescopes (MASTER-Net: http://observ.pereplet.ru, 6 Very Wide Field cameras and 2 Wide Field Telescopes ) located near Kislovodsk was pointed to the GRB 100816A (Oates et al., GCN Circ N 11102) 21 sec after Notice time and 1350 s after trigger time (before sunrise). start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? Filter -------------------------------------------------------------------------- 01:00:21.0 01:03:21.0 180 17.2 1350.0 N Polarization There are 6 very wide field cameras located at Kislovodsk with total FOV = 3 000 square degrees. Unfortunately, GRB was 4 degrees outside FOV. The message may be cited. mailto: lipunov@sai.msu.ru //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11106 SUBJECT: GRB 100816A: TAROT Calern observatory optical detection DATE: 10/08/16 14:38:10 GMT FROM: Alain Klotz at CESR-CNRS Klotz A. (CESR-OMP), Gendre B. (IASF), Boer M. (OHP-OAMP), Atteia J.L. (LATT-OMP) report: We imaged the field of GRB 100816A detected by SWIFT (trigger 431764) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 1339s after the GRB trigger The elevation of the field increased from 72 degrees above horizon and weather conditions were good. We co-added a series of 30s unfiltered exposures. We detect the OT mentioned by Oates et al. 2010 (GCNC 11102) very close to the limiting magnitude of the image : start exp. = 1339s end exp. = 1601s R ~ 19.2 Magnitudes were estimated with the nearby star NOMAD-1 1165-0624306 and are not corrected for galactic dust extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11108 SUBJECT: GRB 100816A: CQUEAN riz-band Detection, Host Galaxy? DATE: 10/08/16 15:59:01 GMT FROM: Myungshin Im at Seoul Nat U Myungshin Im, Won-Kee Park (CEOU/Seoul National Univ), Soojong Pak, Hyeonju Jeong, Eunbin Kim, and Jinyoung Kim (Kyunghee University) We observed GRB 100816A (Palmer et al. GCN 11102) with the SDSS r,i,z-filters during the commissioning run of CQUEAN (the Camera for QUasars in the Early uNiverse)on the 2.1m telescope at the McDonald observatory. The observation started at 2010 August 16, 08:33:46 UT, about 8 hours after the BAT trigger. A series of 300 secs exposures were taken. We identify an object within the error circles reported by UVOT (Palmer et al. GCN 11102), and by Antonelli et al. (GCN 11104) which faded significantly, confirming its GRB afterglow nature. We also notice another extended object, about 1.3" to the South of the afterglow at RA=23:26:57.53 and Dec= +26:34:41.6 with ~0.4" error in position. The close proximity of the object to the afterglow suggests that this second object is possibly a host galaxy of GRB 100816A, although a chance projection cannot be ruled out. GRB host GRB+host mid-point (UT) r (unresolved) 21.4 08:39:36 i 21.31 20.58 - 08:45:08 The magnitudes are in AB, and the error of the photometry is about 0.1 mag. The photometry calibration is done with a standard star observation. The finding charts are available at http://astro.snu.ac.kr/~mim/grb/grb100816A/grb100816A_small.jpg http://astro.snu.ac.kr/~mim/grb/grb100816A/grb100816A_large.jpg N is up, and E is left. Further analysis of the data is ongoing. We thank the staffs of the McDonald observatory, David Doss, Peter S. Odoms, and John Kuehne for their assistance of the CQUEAN commissioning run. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11109 SUBJECT: GRB 100816A: Gemini-N imaging DATE: 10/08/16 16:03:01 GMT FROM: Nial Tanvir at U.Leicester N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick), D. Perley (UC Berkeley) report on behalf of a larger collaboration: We imaged the field of possibly short GRB 100816A (Oates et al. GCN 11102) with Gemini-N/GMOS, beginning about 11:33 (UT), approximately 11 hours post-burst. The afterglow detected by UVOT and confirmed to be fading by the TNG (Antonelli et al. GCN 11104) is clearly detected at a magnitude R~22.4, calibrated against USNO-B1 stars in the field. We also detect a relatively bright galaxy centred about 1.2 arcsec south of the afterglow, which may well be the host of the burst. The magnitude of the galaxy is comparable to that of the afterglow at this time. Analysis of spectroscopic observations is ongoing. We thank the Gemini observers, particularly Alexander Fritz, for their assistance in obtaining these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11110 SUBJECT: GRB 100816A: Enhanced Swift-XRT position DATE: 10/08/16 17:30:46 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 406 s of XRT Photon Counting mode data and 1 UVOT images for GRB 100816A, 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 = 351.74010, +26.57887 which is equivalent to: RA (J2000): 23h 26m 57.62s Dec (J2000): +26d 34' 43.9" with an uncertainty of 1.6 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) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11111 SUBJECT: GRB 100816A, Swift-BAT refined analysis DATE: 10/08/16 17:33:20 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift C. B. Markwardt (GSFC/UMD), 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), S. R. Oates (UCL-MSSL), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-119 to T+263 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100816A (trigger #431764) (Oates, et al., GCN Circ. 11102). The BAT ground-calculated position is RA, Dec = 351.738, 26.568 deg which is RA(J2000) = 23h 26m 57.1s Dec(J2000) = +26d 34' 04.4" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 33%. The mask-weighted light curve shows a single symmetric peak. There is low-level ongoing emission out to about T+100 sec. T90 (15-350 keV) is 2.9 +- 0.6 sec (estimated error including systematics). The time-averaged spectrum from T-0.7 to T+4.5 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.73 +- 0.24, and Epeak of 170.7 +- 79.7 keV (chi squared 50.79 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.0 +- 0.1 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+0.10 sec in the 15-150 keV band is 10.9 +- 0.4 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.16 +- 0.06 (chi squared 61.72 for 57 d.o.f.). 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/431764/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11112 SUBJECT: GRB 100816A: 1.23m CAHA optical observations DATE: 10/08/16 18:39:32 GMT FROM: Javier Gorosabel at IAA-CSIC V. Terron, M. Fernandez, A.J. Castro-Tirado, J. Gorosabel (IAA-CSIC), report on behalf of a larger collaboration: We carried out BVRI-band observations of the Swift GRB 100816A (Oates et al., GCNC 11102) with the 1.23m Calar Alto telescope. The optical afterglow (Oates et al., GCNC 11102; Antonelli et al., GCNC 11104) is well detected in BVRI with a preliminary magnitude of I~19.9 on Aug 16.0492 UT (~33 min post burst), calibrated using USNO-B1.0 field stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11113 SUBJECT: GRB 100816A: Swift-BAT spectral lag results DATE: 10/08/16 18:58:58 GMT FROM: Scott Barthelmy at NASA/GSFC J. Norris (U. Denver), T. N. Ukwatta (GWU/GSFC), S. D. Barthelmy (GSFC), N. Gehrels (GSFC), M. Stamatikos (OSU/NASA/GSFC), and T. Sakamoto (GSFC/UMBC) for the Swift-BAT team: For GRB 100816A (Oates et al GCN 11102), the BAT team has analyzed the spectral lags for the data from ~T-1 sec to ~T+3 sec using unmask-weighted light curves. The spectral lags were measured between standard BAT energy bands: channel 1 (15-25 keV), 2 (25-50 keV), 3 (50-100 keV) and 4 (100-350 keV) are given below. Lag Ch4-2 10 +/- 25 ms Lag Ch3-1 20 +/- 20 ms We conclude from this analysis that the burst is consistent with being a short hard burst, but the error bars are too large to be definitive. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11114 SUBJECT: GRB100816A Swift-XRT refined analysis DATE: 10/08/16 20:00:21 GMT FROM: Owen Littlejohns at U of Leicester O. M. Littlejohns (U. Leicester) and S. R. Oates (UCL-MSSL) report on behalf of the Swift-XRT team:   We have analysed 4.4 ks of XRT data for GRB 100816A (Oates et al. GCN Circ. 11102), from 89 s to 12.2 ks after the BAT trigger. The data comprise 144 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 11110).   The light curve can be modelled with a power-law decay with a decay index of alpha=1.29 (+0.05, -0.04), with some flaring activity during the first snapshot.   A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.16 (+0.22, -0.21). The best-fitting absorption column is 1.4 (+0.5, -0.4) x 10^21 cm^-2, in excess of the Galactic value of 4.5 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.10 (+0.19, -0.16) and a best-fitting absorption column of 1.5 (+0.5, -0.4) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.5 x 10^-11) erg cm^-2 count^-1.   If the light curve continues to decay with a power-law decay index of 1.29, the count rate at T+24 hours will be 1.6 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.9 x 10^-14 (8.6 x 10^-14) erg cm^-2 s^-1.   The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00431764. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11115 SUBJECT: GRB 100816A: Swift UVOT Observations DATE: 10/08/16 21:34:49 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) reports on behalf of the Swift/UVOT team: The Swift/UVOT began observing the field of GRB 100816A 91s after the BAT trigger (Oates et al., GCN Circ. 11102). We detect the optical afterglow significantly in the white and u filters and marginally in the v, b and uvw1 filters. The best UVOT position was reported in Oates et al. (GCN Circ. 11102), and is consistent with the XRT enhanced position (Evans et al., GCN Circ 11110) and with the optical afterglow position reported by TNG (Antonelli et al., GCN Circ 11104). Preliminary magnitudes and the 3 sigma upper limits are reported below for individual white and u images and summed images for the v, b, uvw1, uvm2 and uvw2 filters. Filter T_start(s) T_stop(s) Exposure Mag/3SigUL ########################################################### white (FC) 91 241 147 17.01 +/- 0.05 white 586 606 19 18.90 +/- 0.19 v 3991 5626 393 21.56 +/- 0.94 b 4811 6393 341 21.07 +/- 0.35 u (FC) 305 555 246 18.02 +/- 0.08 u 4606 4806 197 20.39 +/- 0.35 uvw1 4401 6036 393 20.98 +/- 0.44 uvm2 4196 34516 1279 > 21.42 uvw2 3787 28671 2475 > 22.19 ########################################################### The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.09 mag (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383,627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11116 SUBJECT: GRB 100816A: Gemini-N spectroscopy DATE: 10/08/16 22:32:01 GMT FROM: Nial Tanvir at U.Leicester N. R. Tanvir, K. Wiersema (U. Leicester), J. P. U. Fynbo (DARK) A. J. Levan (U. Warwick) & D. Perley (UC Berkeley) report on behalf of a larger collaboration: We obtained medium resolution, long-slit spectroscopy of GRB 100816A (Oates et al. GCN 11102) with Gemini-N/GMOS following the imaging reported in Tanvir et al. (GCN 11109).  The afterglow was centred in the slit, and the nearby candidate host galaxy (see also Im et al. GCN 11108) was also partially in the slit.  The spectrum covers a wavelength range from about 4000A to 6700A. Our analysis of the galaxy trace provides a tentative detection of the OIII (5007A/4959A) doublet and Hbeta (4863A) at a redshift of z~0.245, although we caution that all these features are low S/N.  No other lines are clearly seen even though OII 3727A would be within the spectral range (but we note the galaxy continuum is not apparent below about 4700A, in part due to declining detector quantum efficiency in the blue).  Neither have we identified so far any significant features in the afterglow spectrum. This is a similar redshift to a number of Swift short-duration burst hosts, but further observations are encouraged to confirm the result. We thank the Gemini observers, particularly Alexander Fritz, for their assistance in obtaining these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11117 SUBJECT: GRB 100816A : Lulin r'-band observation DATE: 10/08/17 08:02:50 GMT FROM: Yuji Urata at Nat. Central U. Y. Urata (NCU) and K.Y Huang (ASIAA) on behalf of EAFON report; "We started to observe the GRB 100816A (Palmer et al. GCN 11102) using Lulin One-meter Telescope (LOT) with r'-band filter. The observation started at 2010 August 16 18:09 about 17.5 hr after the burst. The brightness of afterglow including the possible host galaxy reported by Im et al. (# 11108) and Tanvir et al (# 11109) is R=21.6+/-0.1 in Vega. The photometric calibration is performed against USNO-B1 stars in the field." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11120 SUBJECT: GRB 100816A: NOT optical observations DATE: 10/08/17 09:24:04 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), D. Xu (Weizmann Inst.), J.P.U. Fynbo (DARK/NBI), P. Jakobsson (Univ. Iceland), L. Buchhave, T. Hansen (NBI), report on behalf of a larger collaboration: We observed the field of GRB 100816A (Oates et al., GCN 11102) with the NOT equipped with ALFOSC. Observations were carried out in the R band. The mid point of the observation is August 17.04 UT (24.3 hr after the GRB). We clearly detect both the optical afterglow (Oates et al., GCN 11102) and the putative host galaxy (Im et al., GCN 11108; Tanvir et al., GCN 11109). We find magnitudes of R = 23.0 +- 0.1 and R = 21.65 +- 0.05 for the two objects, respectively, assuming R=17.06 for the nearby USNO star 1165-0595190. We caution that accurate photometry will have to await for late-time templates to isolate the contribution of both objects. [GCN OPS NOTE(17aug10): Per author's request, TH was added to the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11123 SUBJECT: GRB 100816A: VLT and Gemini-N revised redshift DATE: 10/08/17 12:56:20 GMT FROM: Nial Tanvir at U.Leicester N. R. Tanvir (U. Leicester), S. Vergani (GEPI/Obs. Paris and APC/Univ. Paris 7), J. Hjorth, J. P. U. Fynbo, B. Milvang-Jensen, D. Malesani (DARK), K. Wiersema (U. Leicester),  P. Vreeswijk (Reykjavik), A. J. Levan (U. Warwick) P. Goldoni (APC/Univ. Paris 7 and SAp/CEA), S. Covino (INAF/Brera), & L. A. Antonelli (INAF/Roma) report on behalf of a larger collaboration: We observed the location of possible short-hard GRB 100816A (Oates et al. GCN 11102; Markwardt et al. GCN 11111; Norris et al. GCN 11116) with VLT/X-Shooter on 2010 Aug 17 beginning 04:20 (UT).  We clearly detect the putative host galaxy of the burst, and identify lines of Halpha, Hbeta,  OII (3727), NII (6548/6583) and OIII (5007) in emission and CaII H&K in absorption.  In fact, the system splits (spectrally and spatially) into two components at redshifts z=0.8034 and z=0.8049 (based on a provisional wavelength calibration), possibly indicating an interacting system or reflecting internal velocity components within a single galaxy.  This redshift is inconsistent with the tentative redshift for this galaxy suggested by Tanvir et al. (GCN 11116). We have also re-analysed the Gemini-N GMOS afterglow spectroscopy initially reported in GCN 11116.  The trace shows faint absorption features consistent with MgII (2797/2803A) doublet and FeII (2600A) at a redshift of z=0.8035. The agreement of this redshift with that obtained for the galaxy from the X-shooter data, strongly suggests that it is the host.  We note that none of the emission lines seen in the X-Shooter spectrum are within the spectral range of the GMOS data. We acknowledge the support of the VLT staff, in particular Giovanni Carraro. [GCN OPS NOTE(19aug10): Per author's request, LAT was added to the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11124 SUBJECT: GRB 100816A: Fermi GBM observation DATE: 10/08/17 19:42:54 GMT FROM: Michael Burgess at UAH G. Fitzpatrick (UCD) reports on behalf of the Fermi GBM Team: "At 00:37:50.94 UT on 16th August 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100816A (trigger 303611872 / 100816026), which was also detected by the SWIFT-BAT (Oates et al. 2010, GCN 11102) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 82 degrees. The GBM light curve shows a single pulse with a duration (T90) of about 2 s (50-300 keV). The time-averaged spectrum from T0 to T0+ 2.496 s is best fit by a Band function with Epeak = 136.70 +/- 4.73 keV, alpha = -0.31 +/- 0.05, and beta = -2.77 +/- 0.17 (Castor C-STAT 555.02 for 484 d.o.f.). The event fluence (10-1000 keV) in this time interval is (9.10 +/- 0.13) E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+ 0.38 s in the 10-1000 keV band is 15.59 +/- 0.25 ph/s/cm^2. A power law function with an exponential high energy cutoff fits the spectrum equally well (Castor C-STAT 564.38 for 485 d.o.f.) The cutoff energy, parameterized as Epeak, is 146.30 +/- 3.44 keV and the power law index is -0.38 +/- 0.04. The spectral and temporal analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11125 SUBJECT: GRB 100816A: 10.4-m GTC redshift confirmation DATE: 10/08/17 21:32:54 GMT FROM: Javier Gorosabel at IAA-CSIC J. Gorosabel (IAA-CSIC, Granada), A.J. Castro-Tirado (IAA-CSIC), N. Tanvir (U. Leicester), A. de Ugarte Postigo (INAF-OAB), M. Jelinek (IAA-CSIC), P. Kubanek (IAA-CSIC & U. Valencia), R. Cunniffe (IAA-CSIC), M.D. Pérez-Ramírez (U. Jaen), J.M. Castro Cerón (ESAC), S. Guziy (IAA-CSIC), G. Gómez (GTC, La Palma), and J. Cepa (IAC, Tenerife), report on behalf of a larger collaboration: "We acquired long-slit spectra of the optical afterglow of the possible short-duration GRB 100816A (Oates et al., GCNC 11102) with the 10.4-m Gran Telescopio Canarias (GTC) at the Observatorio del Roque de los Muchachos on the island of La Palma. Three spectra were taken under non optimal weather conditions with the OSIRIS instrument on Aug 16.1736 - 16.2060 UT (3.5-4.3 hr post-burst) with a total exposure time of 3x900s and covering an approximate spectral range of 4200-8700 A. A comparison of the GTC and the Gemini-N spectra (Tanvir et al., GCNC 11123) shows faint absorption features consistent with the MgII doublet at a preliminary redshift of z = 0.8049. At the present stage of the reduction we can not confirm the existence of emission lines." We acknowledge the support of the GTC staff. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11126 SUBJECT: GRB100816A: MITSuME optical upper limits DATE: 10/08/18 06:09:10 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 100816A (Oates et al., GCN 11102) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2010-08-16 14:00:49 UT (~13.4 h after the burst). We did not find any new point source within the enhanced XRT error circle (Evans et al., GCNC 11110) in all the three bands. We could not detect the previously reported host galaxy (Im et al., GCN 11108; Tanvir et al., GCN 11109; Malesani et al., GCN 11120). Three sigma upper limits of the OT are listed below. We used GSC 2.3 catalog for flux calibration. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.67447 16:49:05 6240.0 >21.0 >20.5 >19.9 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11127 SUBJECT: Konus-Wind observation of GRB 100816A DATE: 10/08/18 11:30:01 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The short GRB 100816A (Swift-BAT trigger=431764; Oates et al., GCN 11102; Markwardt et al., GCN 11111) triggered Konus-Wind at T0=02273.983s UT (00:37:53.983) The burst light curve shows a single peak with a total duration of ~2.8 s. There is also a hint of a softer (<70 keV) short (~64ms) weak spike at T0 + 4.7 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB100816_T02273/ As observed by Konus-Wind the burst had a fluence of (3.3 +/- 0.4)x10-6 erg/cm2, and a 64-ms peak flux measured from T0 + 0.896 s of (2.3 +/- 0.4)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+8.448 s) is best fit in the 20 keV - 2 MeV range by a power law with exponential cutoff model, for which alpha = -1.0(-0.3, +0.4), and Ep = 148(-26, +41) keV (chi2 = 50.5/61 dof). Fit of this spectrum by the GRB (Band) model yields the same values of alpha and Ep, with beta = -4.6 (<-2.5), chi2 = 50.5/60 dof. Assuming z=0.8049 (Tanvir et al., GCN 11123; Gorosabel et al., GCN 11125) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_Lambda = 0.73, the isotropic energy release E_iso = (5.8 +/- 0.7)x10^51 erg, the peak luminosity (L_iso)_max = (7.3 +/- 1.3)x10^51 erg/s. All the quoted results are preliminary. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11128 SUBJECT: GRB 100816A: Fermi GBM observation (correction to GCN 11124) DATE: 10/08/18 15:45:25 GMT FROM: Gerard Fitzpatrick at U.College Dublin/Fermi "G. Fitzpatrick (UCD) reports on behalf of the Fermi GBM Team: Apologies, the event fluence (10-1000 keV) should be (3.84 +/- 0.13) E-06 erg/cm^2. This is consistent with the value reported by Konus-Wind (Golenetskii et al, GCN 11127). The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."