This file contains BOTH GRBs 051211A and 051211B. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4324 SUBJECT: HETE SXC localization of GRB 051211 (=H3979) DATE: 05/12/11 07:17:57 GMT FROM: Carlo Graziani at U.Chicago J-L. Atteia, H. Clergeot, G. Ricker, N. Kawai, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki, S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek, J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, G. Pizzichini, and S. Gunasekera, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: At 02:50:05.4 UTC (10205.4 UT) on 11 December 2005 the HETE FREGATE, WXM, and SXC instruments detected GRB 051211(=H3979), a GRB. The flight location was distributed in a GCN Notice at 02:52:22 UTC. Ground analysis showed that the flight X-location derived from the X detector is correct but that the Y-location derived from the Y detector is unreliable, due to the low signal-to-noise of the burst in the Y detector. As a result, we believe that the flight location distributed in the GCN Notice is incorrect. Ground analysis of WXM data yields several possible Y locations. One of these locations corresponds to a location found through analysis of the SXC data corresponding to much softer emission about 35s after the trigger. This may represent soft emission following the hard peak that triggered HETE. This SXC location was distributed in a GCN Notice at 05:58:30 UT. The location is: R.A. = 06h 56m 13s ; Dec. = 32d 40' 44" (J2000), with a 90% confidence error radius of 80". We caution that while this is our best estimate of the burst location, under the circumstances we cannot be absolutely certain that this location is correct. Further analyses are in progress. Further information about this burst will be available at the following URL: http://space.mit.edu/HETE/Bursts/GRB051211 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4325 SUBJECT: GRB 051211:IAC80 optical observations DATE: 05/12/11 10:53:56 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia A. de Ugarte Postigo (IAA-CSIC Granada), S. Fernández-Acosta (IAC Tenerife), S. Guziy, M. Jelínek, S. B. Pandey, J. Gorosabel and A. J. Castro-Tirado (IAA-CSIC) report: "We have imaged a 7' x 7' region centred on the HETE-2/SXC error box for GRB 051211 (Atteia et al. GCNC 4324) with the 0.8-m IAC telescope at the Observatorio del Teide starting on Dec 11.279 UT (i.e. 3.9 hours after the GRB). Two frames (600s exposure time, R-band) were taken under poor meteo- rological conditions (strong wind and increasing background due to the proximity of the twilight). No optical variable is detected in a 3' field centred on the HETE-2/SXC error box down to limiting magnitude of R about 19." This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4326 SUBJECT: GRB 051211: Swift XRT upper limit DATE: 05/12/11 19:32:52 GMT FROM: David Burrows at PSU/Swift G. Cusumano (INAF-IASF), D.N. Burrows, S. Hunsberger, C. Pagani (PSU), V. La Parola, and V. Mangano (INAF-IASF) report on behalf of the Swift XRT team: The Swift XRT began observing HETE-discovered GRB 051211 (Atteia et al., GCN 4324) at 14:43:21 UT on 11 December 2005. In the first two orbits we accumulated 3330 s of exposure time. We find no X-ray counterpart within the HETE/SXC error circle, with a 3 sigma upper limit of 3.19E-3 counts/s (2.0 E-13 erg/s/cm/cm). We note that this is considerably fainter than the typical Swift afterglow at this same time frame, though not inconsistent with the fainter Swift afterglows (Nousek et al. 2005, astroph/0508332). Observations will be terminated at about 19:30 UT on 11 December to prevent overheating of the XRT detector. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4327 SUBJECT: GRB 051211B: a long GRB detected by INTEGRAL DATE: 05/12/11 23:22:59 GMT FROM: Sandro Mereghetti at IASF/CNR S. Mereghetti (IASF, Milano), D.Gotz (CEA, Saclay), N. Mowlavi, D.Eckert, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report: A GRB lasting about 80 s has been detected by IBAS in IBIS/ISGRI data at 22:05:44 on December 11 2005. Its refined coordinates (J2000) are: RA: 345.688 [degrees] DEC: 55.079 [degrees] with an uncertainty of 2.0 arcmin (90% c.l. radius). Its preliminary peak flux (20-200 keV, 1s integration time) is about 0.8 ph (8x10e-8 erg)/cmsq/s. Its fluence (20-200 keV, 80 s integration time) is 2x10e-6 erg/cmsq. A plot of the light curve will be posted at http://ibas.mi.iasf.cnr.it/IBAS_Results.html This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4328 SUBJECT: GRB 051211B: a possible optical detection by TAROT DATE: 05/12/12 00:22:43 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Boer M. (OHP), and Atteia, J.L. (LAT-OMP) report: We imaged the entire field of GRB 051211b (trig 2712) detected by INTEGRAL (Mereghetti et al. GCNC 4327) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. Observations started 9 seconds after the GCN notice (and 28.7 s after the GRB). The field had an elevation of 43 degrees above horizon at the begining of the observations. The sky was covered by clouds except for only one unfiltered image started on 2005-12-11T22:08:29.51 (GRB+131s) and ended on 2005-12-11T22:08:59.51 (GRB+161s). On this image, we detect a candidate for the afterglow of the GRB at R ~ 16.2 +/- 0.6 : RA = 23 02 48.9 DEC = +55 05 06.0 J2000.0 This object is not seen on the DSS2-R, nor on the 2MASS-K, nor in the USNO-B1. The image can be seen at http://www.cesr.fr/~klotz/grb051211b This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4329 SUBJECT: GRB 051211: TAROT optical limits DATE: 05/12/12 00:23:57 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Boer M. (OHP), and Atteia, J.L. (LAT-OMP) report: We imaged the entire field of GRB 051211 (H3979) detected by HETE-2 (Atteia et al. GCNC 4324) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. Observations started 8.1 seconds after the GCN notice (and 3.14 hours after the GRB). The field had an elevation of 33 degrees above horizon at the begining of the observations and then decreased. Two images of 90s were co-added. We compared the 3 arcmin field centred on the HETE-2/SXC error box with stars of the USNO-B1 catalog. No new source appears brighter than R=15.3. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4332 SUBJECT: GRB 051211B: Swift XRT Observations DATE: 05/12/12 04:46:11 GMT FROM: David Burrows at PSU/Swift C. Pagani (INAF-OAB), D. N. Burrows (PSU), V. Mangano and V. La Parola (INAF-IASF) report on behalf of the Swift XRT team: The Swift XRT began observing GRB 051211B, detected by INTEGRAL (Mereghetti et al., GCN 4327), at 01:05:28 UT on 12 December 2005 (10.8 ks after the burst). In the first orbit of data (2.4 ks of exposure time), an uncataloged X-ray source was detected at the following position: RA,Dec = 345.6762,+55.081 {23:02:42.3, +55:04:51.7} (J2000) with an uncertainty of 4.5 arcsec radius (90% containment). This position includes corrections for the XRT boresight. We detected 58 photons from this source in Photon-Counting mode at a count rate of 0.024 cps, corresponding to an observed flux of about 1.3x10-12 ergs/cm^2/sec. The X-ray source is 25 arcsec from the INTEGRAL position (GCN 4327) and 58 arcsec from the candidate optical afterglow reported in GCN 4328. There is no X-ray source visible at the position of the candidate optical afterglow. With the data available at this time we cannot determine whether or not this source is fading. Observations are continuing, and we will report further results in a later circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4333 SUBJECT: GRB 051211A and GRB051211B: BOOTES simultaneous observations DATE: 05/12/12 07:14:03 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia M. Jelínek, A. J. Castro-Tirado, S. Vitek, A. de Ugarte Postigo (IAA-CSIC Granada), P. Kubánek and R. Hudec (Astronomical Institute of the Academy of Sciences, Ondrejov), report: The BOOTES instruments in South Spain responded to the two GRBs detected on 11 Nov 2005. The BOOTES-2 very wide field camera located at La Mayora (EELM-CSIC, Málaga) observed the region of the sky containing the HETE-2/SXC error box for GRB 051211A (Atteia et al. GCN 4324) as part of the routinary observing schedule. A 30s exposure started at 2:50:00 UT (5s prior to the beginning of the 33s long burst), i.e. overlaping with the single, hard gamma-ray peak detected by HETE-2. This image sets a R = 10 upper limit to the promt optical flash for GRB 051211A. BOOTES-1 in El Arenosillo (INTA, Huelva), responded under non-optimal conditions to the GRB 051211B trigger (Mereghetti et al. GCNC 4327). A sequence of exposures started at 22:06:34 UT (50s after the GRB onset, 30s after the GCN notice), i.e. overlaping for 30 s with the tail of the gamma-ray emission. We do no detect any transient optical emission in the 2' INTEGRAL error box and in particular at the position of the possible afterglow reported by Klotz et al. (GCNC 4328). We set a I > 14 limit to any optical emission arising simultaneusly to the gamma-rays. We also notice moderate extinction in the line of sight: E(B-V) = 0.47 from the Schlegel et al. dust maps (1998)." This message can be quoted. [GCN OPS NOTE(16dec05): Per author's request, the duplicate text was removed.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4334 SUBJECT: GRB051211b: P60 Observations DATE: 05/12/12 07:15:56 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko, A. M. Soderberg (Caltech), and D. B. Fox (Penn State) report on behalf of a larger collaboration: We have imaged the field of the Integral GRB051211b (Mereghetti et al., GCN 4327) with the automated Palomar 60-inch telescope. Observations consisted of one 120 s exposure in the Kron R and one 120 s exposure in i' at approximately 12 December 03:20 UT (5.2 hours after the burst). Further observations were precluded by inclement weather. By comparison with the Second Digital Sky Survey, we find no new sources in the Integral error circle to the 3-sigma limits R > 19.0, I > 18.0 (calculated with respect to USNOB R2 and I2 magnitudes). In particular, we find no objects inside the XRT error circle (Pagani et al., GCN 4332) or associated with the possible TAROT afterglow (Klotz et al., GCN 4329) to the same limits. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4335 SUBJECT: GRB 051211: IAC80 optical observations DATE: 05/12/12 09:30:56 GMT FROM: Alberto Castro-Tirado at LAEFF-INTA A. de Ugarte Postigo (IAA-CSIC Granada), S. Fernández-Acosta (IAC Tenerife), S. Guziy, M. Jelínek, S. B. Pandey, J. Gorosabel and A. J. Castro-Tirado (IAA-CSIC) report: "We have imaged a 7' x 7' region centred on the HETE-2/SXC error box for GRB 051211 (Atteia et al. GCNC 4324) with the 0.8-m IAC telescope at the Observatorio del Teide starting on Dec 11.279 UT (i.e. 3.9 hours after the GRB). Two frames (600s exposure time, R-band) were taken under poor meteo- rological conditions (strong wind and increasing background due to the proximity of the twilight). No optical variable is detected in a 3' field centred on the HETE-2/SXC error box down to limiting magnitude of R about 19." This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4336 SUBJECT: GRB 051211b: RTT150 optical observations DATE: 05/12/12 11:55:05 GMT FROM: Rodion Burenin at IKI, Moscow I. Khamitov (TUG), I. Bikmaev, R. Zhuchkov, N. Sakhibullin (KSU/AST) Z. Aslan (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI) report: The error box of GRB 051211b (INTEGRAL trig. 2712; Mereghetti et al, GCN4327) was observed with Russian-Turkish 1.5-m telescope (RTT150, Bakyrlytepe, TUBITAK National Observatory, Turkey), starting at Dec. 11, 22:23UT, i.e. 18 min after the burst. Observations were started at zenith distance Z=69 degrees and were continued until the object descended into the clouds near the horizon. We made 30x60s exposures in R. The first 20 images were taken in clear sky but the last 10 images show a variable background because of clouds and bright Moon. We did not find the afterglow candidate reported by Klotz et al. (GCN4328) nor on first 60s image nor on image of 20 co-added good images. At the XRT position (Pagani et al., GCN 4332) we marginally detected only one source near the detection limit of our combined image. The coordinates of this source are: 23:02:42.25 +55:04:53.4 (J2000). The finding chart can be found at: http://hea.iki.rssi.ru/~rodion/GRB/051211b/r.jpg Using USNO-B1 stars we estimate limiting magnitude in our combined image as R=~22.3. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4337 SUBJECT: GRB051211B: Liverpool Telescope observation DATE: 05/12/12 13:25:51 GMT FROM: Cristiano Guidorzi at ARI,Liverpool JMU C. Guidorzi, I.A. Steele, C.J. Mottram, A. Monfardini, C.G. Mundell, A. Gomboc, R.J. Smith, M.F. Bode (Liverpool JMU) report: "The 2-m Liverpool Telescope located in La Palma, Canary Islands, observed GRB051211B detected by INTEGRAL (Mereghetti et al. GCN 4327) ~66 min after the GRB trigger time. The observation could not commence earlier because of the weather. The "detection mode" procedure did not detect any obvious candidate brighter than about r'=16 mag from 3x10-s images. The limiting magnitude is due to poor sky conditions and bright moonlight. After visual inspection of a 6-min stacked image started at ~93 min after the burst, we detect neither the optical candidate found by Klotz et al. (GCN 4328) nor any counterpart to the X-ray source reported by Swift/XRT (Pagani et al., GCN 4332), down to r'~18. The limiting magnitude is automatically calculated with respect to the USNOB1.0 'R2' values of the field objects." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4338 SUBJECT: GRB 051211B: Swift XRT confirmation of the afterglow DATE: 05/12/12 13:51:50 GMT FROM: David Burrows at PSU/Swift V. La Parola, V. Mangano (INAF-IASF), C. Pagani (INAF-OAB), and D. N. Burrows (PSU), report on behalf of the Swift XRT team: The Swift XRT began observing GRB 051211B, detected by INTEGRAL (Mereghetti et al., GCN 4327), at 01:05:28 UT on 12 December 2005 (10.8 ks after the burst). With five orbits of data (from 11 ks to 36 ks after the burst), the uncataloged X-ray source reported in Pagani et al. (GCN 4332) is clearly fading, consistent with being the afterglow of this burst. Our updated position is RA 23:2:41.76, Dec 55:04:51.9 (345.6740, 55.0811), which is 29".8 from the INTEGRAL position and 62".9 from the position of the candidate optical afterglow reported in GCN 4328 (Klotz et al.). The lightcurve is initially flat, with a steep power law decay commencing about 20 ks after the burst. Observations are continuing. Refined analysis, including decay indices and spectral results, will be issued in a further circular after accumulation of several more orbits of data. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4339 SUBJECT: GRB 051211A,optical observation DATE: 05/12/12 13:52:06 GMT FROM: Shouta Maeno at U.of Miyazaki S.Maeno,E.Sonoda,M.Yamauchi (University of Miyazaki) "We have observed the field covering the error circle of GRB 051211A (GCN 3979) with the unfiltered CCD camera on the 30-cm telescope at University of Miyazaki. The observation was started 11:06:34 UT on Dec.11. After co-adding a set of 18 images (11:06:34 UT - 11:28:23 UT) of 30 sec exposures, we have compared with the USNO-A2.0 catalog. Preliminary analysis shows there is no new source brighter than 17.2 mag." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4340 SUBJECT: GRB 051211B: Swift/UVOT upper limits DATE: 05/12/12 14:02:43 GMT FROM: Alexander Blustin at MSSL-UCL A. J. Blustin (UCL-MSSL), V. La Parola (INAF-IASF), M. Chester (PSU), L. Angelini (GSFC-JHU), N. Gehrels (GSFC) on behalf of the Swift/UVOT team The Swift/UVOT began observing the field of GRB 051211b at 01:05:32 on 2005-12-12, ~3 hours after the INTEGRAL trigger (Mereghetti et al., GCN 4327). No source was detected at either the XRT (Pagani et al., GCN 4332) or Magellan (Klotz et al., GCN 4328) positions in summed images down to the following 3-sigma upper limits (not corrected for extinction). Filter T_range(hours) Exp(s) 3sigUL(mag) V 3-11.5 7165 21.0 M2 3.25-11.75 7279 21.3 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4341 SUBJECT: GRB 051211B: Swift/UVOT upper limits - correction DATE: 05/12/12 14:37:23 GMT FROM: Alexander Blustin at MSSL-UCL A. J. Blustin (UCL-MSSL) Correction to GCN 4340 (Blustin et al.): No source was detected at the TAROT (Klotz et al., GCN 4328) position (not Magellan). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4342 SUBJECT: GRB 051211A: Swift/UVOT upper limits DATE: 05/12/12 15:48:34 GMT FROM: Alexander Blustin at MSSL-UCL A. J. Blustin (UCL-MSSL), G. Cusumano (INAF-IASF), J. Greiner (MPE), D. Hinshaw (GSFC-SPSYS), N. Gehrels (GSFC) on behalf of the Swift/UVOT team The Swift/UVOT began observing the field of GRB 051211a at 15:50:04 UT on 2005-12-11, 13 hours after the HETE trigger (Atteia et al., GCN 4324). No potential optical/UV counterpart was found in co-added images in any of the filters, within the reported 80 arcsec radius (90% confidence) HETE error circle, down to the following 5-sigma magnitude upper limits (not corrected for extinction). Filter T_range(hours) Exp(s) 5sigUL(mag) V 14.9-15.1 886 19.4 B 13.5-13.7 738 20.2 U 13.3-16.7 1469 20.3 W1 13.0-16.5 1800 20.0 M2 11.9-15.3 1502 20.1 W2 14.6-14.9 900 20.1 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4343 SUBJECT: GRB051211B, RBO optical observations DATE: 05/12/12 22:27:58 GMT FROM: Chris Rodgers at U of Wyoming D. Allen, C. Rodgers, R. Canterna (University of Wyoming) report on behalf of the Red Buttes Observatory (0.6m) GRB Team as part of the FUN GRB Collaboration. We responded to GRB 051211B (INTEGRAL trig. 2712; Mereghetti et al, GCN4327) at 2005/12/12 00:59:37 UT with two 10 minute I and R exposures centered on the position of the original INTEFRAL GRB Position under 4.6 arcsecond photometric conditions. The source was not detected in any of the above exposures in the same position reported by Klotz et al. (GCN 4328) due to detection limits. UT Time Since Filter Limiting Magnitude 00:59:37 2.8981 hrs I 18.4 01:10:21 3.0769 hrs I 18.4 01:33:40 3.4656 hrs R 19.2 01:44:15 3.6419 hrs R 19.2 10 sigma limiting magnitude were derived from the USNO-B1.0 catalogue. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4344 SUBJECT: GRB 051211a: RTT150 optical observations DATE: 05/12/12 23:40:20 GMT FROM: Irek Khamitov at TUG R. Zhuchkov, I. Bikmaev, N. Sakhibullin (KSU/AST) R. Burenin, M. Pavlinsky, R. Sunyaev (IKI) I. Khamitov, Z. Aslan (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.), report: The error radius of GRB 051211a (Atteia et al, GCN4324) was observed with Russian-Turkish 1.5-m telescope (RTT150, Bakyrlytepe, TUBITAK National Observatory, Turkey), starting at Dec. 11, 18:38UT, i.e. ~15.8 hours after the burst. Two frames (300s exposures in R and B bands) were taken. We did not detect new sources to compare with DSS frames. Using USNO-B1 stars we estimate limiting magnitude of our images as: t-t0 Band m_lim (hour) (mag) ---------------------- 15.84 R 20.60 15.99 B 20.57 This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4346 SUBJECT: GRB 051211B, optical observation DATE: 05/12/13 16:03:36 GMT FROM: Eri Sonoda at U of Miyazaki/Japan E.Sonoda, S.Maeno, M.Yamauchi, Y.Nakamura, S.Masuda (University of Miyazaki) "We have observed the field covering the error box of GRB 051211B (GCN4327) with the unfiltered CCD camera on the 30-cm telescope at University of Miyazaki. The observation was started 10:01:06 UT on Dec.12 (about 12 hours after the burst). After co-adding a set of 10 images (10:01:06 - 10:13:59 UT) of 30 sec exposures, we have compared with the USNO A2.0 catalog. Preliminary analysis shows there is no new source brighter than 17.9 mag. at the position reported by Klotz, A. et.al.(GCN4328)." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4347 SUBJECT: GRB051211B: XRT refined analysis DATE: 05/12/13 16:04:25 GMT FROM: Valentina La Parola at INAF-IASPA V. La Parola, V. Mangano, G. Cusumano (INAF-IASF), C. Pagani (INAF-OAB), and D. N. Burrows (PSU), D. Hinshaw (GSFC-SPSYS), F. Marshall (GSFC), report on behalf of the Swift XRT team: We report on further analysis of the XRT observation of GRB051211B (Mereghetti et al., GCN 4327; Pagani et al, GCN 4332; La Parola et al., GCN 4338). The XRT observation begins 10.8 ksec after the INTEGRAL trigger. We see a flat phase with a break at 18 ksec from the burst trigger, then the X-ray light-curve decays as a powerlaw with slope -1.16 +/- 0.18. The spectrum of the PC data can be modelled with an absorbed power-law with photon index Gamma = 2.0+/-0.3 (90% confidence level). The absorbing column best fit value is (4.1 +/- 1.3)e21 cm-2, consistent with the Galactic value of 3.3e21 cm-2 The flux at T+24h is 4.4e-13 erg cm^-2 s^-1 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4350 SUBJECT: GRB051211B: Probable radio afterglow DATE: 05/12/14 23:25:49 GMT FROM: Dale A. Frail at NRAO Dale A. Frail (NRAO) reports on behalf of a larger collaboration: "We used the Very Large Array to observe the INTEGRAL burst GRB051211B (GCN4327) at a frequency of 8.46 GHz on 2005 December 14.02 UT. We find a single weak radio source (66+/-19 uJy) coincident with the fading X-ray afterglow identified by the XRT (GCN 4338), with an error of +/-1.3 arcsec in each coordinate. Further observations are planned. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4356 SUBJECT: GRB051211A: possible optical candidate DATE: 05/12/15 14:13:31 GMT FROM: Cristiano Guidorzi at ARI,Liverpool JMU C. Guidorzi, A. Monfardini, I.A. Steele, A. Gomboc, C.G. Mundell, C.J. Mottram, R.J. Smith, D. Bersier, A. Melandri, S. Kobayashi, D. Carter, M.F. Bode (Liverpool JMU), N. Tanvir (Hertfordshire) report: "The 2-m Faulkes Telescope North observed GRB051211A discovered by HETE-2 (Atteia et al, GCN 4324) from 5.9 to 11.9 hours after the burst. So far, searches for afterglow have provided just upper limits in the optical (de Ugarte Postigo et al. GCN 4325 & GCN 4335, Klotz et al. GCN 4329, Jelinek et al. GCN 4333, Maeno et al. GCN 4339, Blustin et al. GCN 4342, Zhuchkov et al. GCN 4344) as well as in the X-rays (Cusumano et al. GCN 4326). From the comparison of two 30-min stacked images, we found an object at RA=06:56:09.0, DEC= +32:40:06.4 (J2000) showing some evidence of a fading of 0.6 +- 0.3 mag (calibrated with USNOB stars of the field, with an uncertainty of 0.4 mag affecting just the absolute values, but not the relative ones). It lies 63 arcsec away from the HETE-2 centroid (given with an error radius of 80 arcsec at 90% CL). ----------------------------------------------------- Start Time Filter Exposure Mag since GRB 6.3 hr R 12x150s 21.15 +- 0.15 11.4 hr R 12x150s 21.75 +- 0.20 ----------------------------------------------------- This candidate does not match any DSS source, although we notice a small blur in the DSS IR that might be either a faint source or a background fluctuation. If we assume the fading is genuine, the average temporal decay power-law index turns out to be around 1.0 +- 0.5. However, a word of caution is required, as the source magnitude is close to the limiting value affected by the moonlight. An image of the OT candidate at both epochs is available at the following: http://www.astro.livjm.ac.uk/~crg/GRB051211A_possible_OT_FTN.jpg We encourage further observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4358 SUBJECT: GRB 051211B: optical afterglow DATE: 05/12/16 13:23:45 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia M. Jelínek, A. de Ugarte Postigo, A.J. Castro-Tirado, V. Casanova, D. Martínez, S. Guziy, S. Castillo, S. B. Pandey and J. Gorosabel (IAA-CSIC Granada): report: "We have imaged a 7' x 7' region containing the INTEGRAL error box for GRB 051211B (Mereghetti et al. GCNC 4327) with the 1.5-m OSN telescope at the Observatorio de Sierra Nevada, starting on Dec 11.94 UT (i.e. 25 min after the GRB). A comparison image has been taken on Dec. 15.86 UT. At the position of the X-ray afterglow detected by Swift/XRT (La Parola et al. GCN 4338) we detect one source that has decreased significantly in brightness in our I-band images. Coordinates yield: RA(2000) = 23:02:41.57,Dec(2000) = +55:04:51.5 (+/-0.4"). This is the likely optical afterglow to GRB 051211B. Images are posted at http://www.iaa.es/~deugarte/GRBs/051211B/GRB051211B.gif . An underlying object seems to be present on the DDS-2 (infrared) which may be a bright host galaxy, detected also on our late I-band image. Further observations are encouraged." This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4359 SUBJECT: GRB051211A (=H3979): Refined Analysis DATE: 05/12/16 18:58:27 GMT FROM: Carlo Graziani at U.Chicago N. Kawai, G. Ricker, J-L. Atteia, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki, S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek, J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, G. Pizzichini, and S. Gunasekera, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: We have analyzed the full FREGATE+WXM+SXC data for HETE trigger H3979 (GRB051211A). Further ground analysis shows that the HETE SXC location for GRB051211A reported in GCN 4324 is reliable. The SXC detected a soft transient source in both the its X and Y cameras about 35 s after the trigger without the assistance of the WXM. The location of this source is: R.A. = 06h 56m 13s ; Dec. = 32d 40' 44" (J2000), with a 90% confidence error radius of 80". The WXM did not detect this soft transient, but it detected hard x-ray emission coincident with the Fregate event. From this hard emission, WXM obtained a solid X location matching the SXC transient. There are several possible WXM Y locations, but one of them matches the SXC transient: the random probability of this is only a few percent. This triple coincidence in time and position gives us high confidence that the SXC transient is associated with the Fregate trigger. The 30-400 keV light curve has a fast rise (<0.1 s) and a slower decay. The burst had a T90 duration of 4.8s in the 6-40 keV band, and of 4.2s in the 30-400 keV band. The integrated spectrum is well-fit by a cutoff power-law function. The best-fit parameters are: alpha = -0.67 --- 90% confidence interval is [-0.90 -0.38] Epeak = 137 keV --- 90% confidence interval is [106 , 200] The 2-30 keV fluence is 1.6e-7 erg/cm2, while the 30-400 keV fluence is 9.6e-7 erg/cm2. This burst had a hardness ratio (100-300 keV fluence)/(25-100 keV fluence) of 1.18. This, along with its 4.2 s T90, places it between the long duration bursts and the short duration bursts in the hardness ratio-duration diagram. We note, however, that if lognormal functions are used to describe the long and short burst duration distributions, this burst appears more likely to belong to the short class. Thus, a search for a possible associated low redshift host galaxy would be of interest. A light curve, hardness ratio-duration diagram, and spectral information for this event are provided at the following URL: http://space.mit.edu/HETE/Bursts/GRB051211/ //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4377 SUBJECT: GRB 051211A: Evidence This Is a Short Burst from Analysis of Spectral DATE: 05/12/21 22:25:49 GMT FROM: Don Lamb at U.Chicago GRB 051211A: Evidence This Is a Short Burst from Analysis of Spectral Lag J. Norris, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki, S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek, J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, G. Pizzichini, and S. Gunasekera, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: We have performed an analysis of the spectral lag for GRB 051211A, using FREGATE data in the 30-85 keV and 85-400 keV energy bands. We obtain a spectral lag of 0.000 +/- 0.024 seconds. This result provides strong additional evidence that GRB 051211A is a short burst [Norris, J. P., Scargle, J. D., and Bonnell, J. T. 2001, in Gamma-Ray Bursts in the Afterglow Era, ed. E. Costa, F. Frontera, and J. Hjorth (Berlin: Springer), p. 40; and Norris, J. P., and Bonnell, J. T. 2005, ApJ, submitted (see, e.g., Figure 3)]. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4422 SUBJECT: GRB051211B: optical observations DATE: 06/01/02 12:34:50 GMT FROM: Alexei Pozanenko at IKI, Moscow D. Sharapov (MAO, and NOT La Palma), N.Marshalkina, M. Ibrahimov (MAO), A.Pozanenko (IKI), V.Rumyantsev (CrAO) on behalf of larger GRB follow up collaboration report: We observed refined error box of X-ray afterglow detected by Swift/XRT (La Parola et al. GCN 4338) of GRB051211B (Mereghetti et al. GCN 4327) with 1.5m telescope of Maidanak Astronomical Observatory on Dec. 12 and Dec.17. Sets of R images of 10x180 s were accumulated in both epochs. We do not detect the candidate in afterglow at coordinates RA(J2000) =23:02:41.57, Dec(J2000) =+55:04:51.5 mentioned by M. Jelinek et al. in GCN 4358. Object to the North-West from fading object referred in GCN 4358 as a possible host galaxy is well detected in our combined images in the both epochs. Using USNO-B1.0 catalog we estimate upper limit and possible host galaxy brightness as following: Obs. time, Exposure, Galaxy, Mag.(UL),Seeing (UT) (s) R(mag) Dec.12 17:16-17:56 1800 21.077+/-0.075 22.0 1.2" Dec.17 14:09-14:45 1800 21.167+/-0.060 22.3 1.1" The source mentioned by Khamitov et al in GCN 4336 is marginally detected on our combined image on Dec.12, and is unlikely to be an afterglow. We would note that the candidate in afterglow at coordinates RA(J2000) =23:02:41.57, Dec(J2000) =+55:04:51.5 is well visible in RTT150 image. Combined images can be found at http://grb.rssi.ru/GRB051211b/. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4623 SUBJECT: GRB 051211A: MDM Observations DATE: 06/01/31 00:15:50 GMT FROM: Jules Halpern at Columbia U. J. P. Halpern (Columbia U.) & N. Mirabal (U. Michigan) report on behalf of the MDM Observatory GRB follow-up team: "Guidorzi et al. (GCN 4356) reported a possible optical afterglow for the HETE-2 burst GRB 051211A (Atteia et al., GCN 4324; Kawai et al., GCN 4359) that faded from R = 21.15+/-0.15 to R = 21.75+/-0.20 between 6.3 hr and 11.4 hr after the burst. As they noted that there is a hint of its presence on the I-band POSS plate, and in view of the likelihood that this was a short burst (Norris et al., GCN 4377), it is interesting to follow up on this candidate afterglow to determine if it is hosted by a relatively nearby galaxy. We observed and detected the same object on 2005 Dec. 25 with the MDM 2.4m telescope and RETROCAM imager in five 300 s exposures in the SDSS r' filter. Its position is R.A. = 06:56:09.00, Decl. = +32:40:06.3 (J2000), the same as previously determined. Calibration with Landolt stars yields R = 21.72+/-0.05 (statistical), with an additional systematic uncertainty of 0.1 likely. This is consistent with the later measurement of Guidorzi et al., but not their earlier one. The object is not resolved in our images at the seeing of 0.95", which argues against a host interpretation. We observed it again in the I band with the MDM 8K imager on 2006 Jan. 29. Three 600 s exposures were obtained in seeing of 0.85". Although the latter images are uncalibrated, the object appears not to have faded, is still at the limit of the I-band POSS plate, and is still unresolved. Therefore, we conclude that it is most likely a star and not the afterglow of GRB 051211A. The MDM I-band image is posted at http://www.astro.columbia.edu/~jules/grb/051211a/ This message may be cited"