This file contains both GRB 050911A and 051109B. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4211 SUBJECT: GRB 051109: ROTSE-III Detection of Possible Counterpart DATE: 05/11/09 01:21:11 GMT FROM: Eli Rykoff at U of Michigan/ROTSE E.S. Rykoff (U Mich), B. Schaefer (Louisiana State), W. Rujopakarn (U Mich), F. Yuan (U Mich), R. Quimby (U Texas), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 051109 (Swift trigger 163136). The first image was at 01:12:52.7 UT, 32.1 s after the burst (4.7 s after the GCN notice time). The unfiltered images are calibrated relative to USNO A2.0. We detect a new object, not visible in the DSS (second epoch), with coordinates: 22:01:15.3 +40:49:23.3 (J2000) start UT mag mlim(of image) ---------------------------------- 01:12:52.7 15.4 16.8 Continuing observations are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4212 SUBJECT: GRB 051109a: IR Detections DATE: 05/11/09 02:09:23 GMT FROM: Josh Bloom at UC Berkeley J. S. Bloom, on behalf of a larger collaboration, reports: "The Peters Automated Infrared Imaging Telescope (PAIRITEL) autonomously began observing the field of GRB 051109a (Swift trigger 163136) at 2005-11-09 01:13:55.59 UTC (1min35 sec after the trigger). In the first several individual 7.8 second exposures we detected the candidate afterglow proposed by Rykoff et al. (GCN #4211) in simultaneous J, H, and Ks imaging. Further observations are in progress as well as analysis." Josh //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4213 SUBJECT: GRB051109: Swift detection of a burst DATE: 05/11/09 02:14:42 GMT FROM: David Palmer at LANL G. Tagliaferri (INAF-OAB), S. Barthelmy (GSFC), D. Burrows (PSU), M. Chester (PSU), N. Gehrels (GSFC), J. Hill (GSFC/USRA), S. T. Holland (GSFC/USRA), J. Kennea (PSU), F. Marshall (GSFC), T. Mineo (INAF-IASFPA), D. Palmer (LANL), T. Sakamoto (GSFC), on behalf of the Swift team: At 01:12:20 UT, Swift-BAT triggered and located GRB051109 (trigger=163136). The spacecraft slewed immediately. The BAT on-board calculated location is RA,Dec= 330.296d, +40.837d {22h 01m 11s, +40d 50' 15"} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve showed a multi-peak structure with a total duration of at least 25 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~2 seconds after the trigger. The XRT began observing at 01:14:20 UT, 120 seconds after the BAT trigger. The XRT on-board software located a bright, previously uncatalogued, fading point source in the field at the following location: RA(J2000): 22:01:15.5, Dec(J2000): +40:49:21.7, with an estimated uncertainty of 5.8 arcseconds (90% containment). This position lies 74 arcseconds from the BAT position reported above, and 2.8 arcseconds from the ROTSE position (Rykoff et al., GCN 4211). The initial flux estimate of this source is 1.1 x 10^-9 erg/s/cm^2. The UVOT began observing at 01:14:23, 123 seconds after the BAT trigger. A bright, uncataloged source is apparent at RA,dec=330.3136,+40.8231 {22h01m15.26s, +40o49'23.2"} (J2000), coincident with the position of the ROTSE detection. The V-band magnitude is approximately 17; this magnitude is based on an on-board source detection algorithm and a more accurate brightness will be available following analysis of the full data set. V-band extinction in the direction of the UVOT position is A_V = 0.63. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4214 SUBJECT: GRB 051109A: ROTSE-III Decline rate for Optical Counterpart DATE: 05/11/09 02:38:04 GMT FROM: Brad Schaefer at LSU B. E. Schaefer (Louisiana State), E.S. Rykoff (U Mich), W. Rujopakarn (U Mich), F. Yuan (U Mich), R. Quimby (U Texas), K. Alatalo (Berkeley), T.A. McKay (U Mich), C. Akerlof (U Mich), report on behalf of the ROTSE collaboration: A fast fading optical transient has been discovered inside the error circle for GRB 051109A (Swift trigger 163136) by the ROTSE-IIIb telescope, located at McDonald Observatory (cf. Rykoff et al. GCN 4211). The source faded as a power law. At the central time of UT 01:16:05 (228 seconds after the Swift trigger), the magnitude was 16.21. (Magnitudes are unfiltered and calibrated against R-band magnitudes for nearby comparison stars.) The source is continuing to fade, but accurate magnitudes will have to await a more detailed analysis due to nearby faint stars. With these magnitudes, the power law index for the decline is -0.4. If this decline continues unbroken, then at a time around two hours after the burst (UT 03:12), the magnitude should be 17.7. Eight hours after the burst (UT 09:12), a magnitude of 18.3 might be expected. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4215 SUBJECT: GRB 051109a: MDM Observations DATE: 05/11/09 03:52:12 GMT FROM: Jules Halpern at Columbia U. N. Mirabal (U. Michigan), J. P. Halpern, and S. Tonnesen (Columbia U.) report on behalf of the MDM Observatory GRB follow-up team: "We are observing the afterglow of Swift GRB 051109 detected by ROTSE-IIIb (Rykoff et al. GCN #4211, Schaefer et al. GCN #4214) using the MDM 2.4m telescope and a Gunn r filter under partly cloudy conditions. From 38 minutes to 148 minutes after the burst, the OT faded from R = 18.21 +/- 0.05 to R = 19.22 +/- 0.08. Magnitudes are referenced to a USNO B1.0 star at 22h01m14.60s +40d49'25.3" (J2000) having R=17.23. This corresponds to a power-law decay index of -0.68. Observations are continuing." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4216 SUBJECT: GRB 051109a: IR Photometry and Astrometry DATE: 05/11/09 04:17:16 GMT FROM: Josh Bloom at UC Berkeley J. S. Bloom (UC Berkeley), C. H. Blake (Harvard), D. Starr (Gemini) and K. Alatalo (UC Berkeley) report: "We have continued to observe the field of GRB 051109a (Tagliaferri et al. 4213) at the position of the optical transient (GCNs 4211, 4214, 4215). Using a stack of PAIRITEL imaging from 2005-11-09 01:18:42.25 to 2005-11-09 01:33:14.94 UTC we find a 2MASS calibrated photometry of J = 15.69 +/- 0.03, H = 14.95 +/- 0.03, Ks = 14.44 +/- 0.04. We also find an astrometric position of (J2000) 22:01:15.313, +40:49:23.31 with an uncertainty of 100 mas in each axis. This is consistent with the Rykoff et al. position." This message may be cited //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4217 SUBJECT: GRB 051109: Swift-BAT refined analysis DATE: 05/11/09 04:25:01 GMT FROM: Takanori Sakamoto at NASA/GSFC E. Fenimore (LANL), L. Angelini (GSFC-JHU), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), J. Greiner (MPE), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC), on behalf of the Swift-BAT team: Using the data set from T-60 to T+70 sec from the recent telemetry downlink, we report further analysis of BAT GRB 051109 (trigger #163136) (Tagliaferri, et al., GCN 4213). The BAT ground-calculated position is (RA,Dec) = 330.295, +40.836 {22h 01m 10.7s, +40d 50' 10.5"} [deg; J2000] +-2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 9%. The lightcurve has two peaks. The initial strong peak starts at T-5 sec with a duration of 20 sec. The second weaker peak starts at T+21 sec. with a duration of 20 sec. T90 (15-350 keV) is (36 +- 2) sec (estimated error including systematics). The power law index of the time-averaged spectrum is 1.5 +- 0.2. The fluence in the 15-150 keV band is (2.1 +- 0.3) x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T0+0.4 sec in the 15-150 keV band is (3.7 +- 0.7) ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4218 SUBJECT: GRB051109: Early Super-LOTIS Detection DATE: 05/11/09 05:21:00 GMT FROM: Grant Williams at Steward Observatory P. A. Milne, G. G. Williams (U. of Arizona), H. S. Park (LLNL), S. Barthelmy (GSFC) The automated 0.6-m Super-LOTIS telescope began observations of the error region of GRB051109 (Swift trigger 163136) at 01:13:03.6 UT, 43.0 seconds after the burst. The OT detected by the Rykoff et al. (GCN 4211) is clearly visible in the first image and subsequent images. We confirm that the OT has faded in images taken 13 minutes after the burst. The R-band magnitude of the afterglow in the first image is: UT Time Delta-Time R magnitude error 01:13:03.6 43.0 s 15.27 0.13 Reported magnitudes are relative to the R1 magnitudes of five stars in the USNO-B catalog. Additional observations are underway. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4219 SUBJECT: GRB 051109: Rc and Ic observations DATE: 05/11/09 06:14:38 GMT FROM: Ken ichi Torii at RIKEN K. Torii (Osaka U.) reports: The error region of GRB 051109 (Tagliaferri et al. GCN 4213) was observed by the 0.3 m telescopes in the New Mexico Skies Observatory. Starting at 01:17:46 UT (326 s after the burst), 120 s exposures in Ic band was obtained. We also observed the field in Rc band (120 s exposures) with another 0.3 m telescope at the same site, starting at 01:29:39 UT. As a result of the preliminary analysis, the optical afterglow (Rykoff et al. GCN 4211) is detected in Ic band as follows, relative to USNO-B1.0 I magnitude. ------------------------------------------ StartUT Filter Mag Nframes ------------------------------------------ 01:25:25 Ic 16.6 1 ------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4220 SUBJECT: GRB 051109: PROMPT Detections DATE: 05/11/09 06:20:02 GMT FROM: Josh Haislip at U.North Carolina J. Haislip, M. Nysewander, M. Bayliss, A. LaCluyze, D. Reichart, J. A. Crain, and A. Foster report on behalf of the UNC team of the FUN GRB Collaboration. Under the control of Skynet, PROMPT Temporary Telescope 3 automatically observed the localization of GRB 051109 (Tagliaferri et al., GCN 4213) beginning 1.7 min after the burst in repeating blocks of B and V. PROMPT Temporary Telescope 5 joined PROMPT-3 15.6 min after the burst in repeating blocks Rc and Ic. These observations were carried out in synch with PROMPT-3's observations. We detect the afterglow (Rykoff et al., GCN 4211) in single V, Rc, and Ic exposures and measure its brightness to be V ~ 16.6 mag at 3.3 min after the burst. PROMPT is still being built and commissioned. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4221 SUBJECT: GRB 051109: HET Optical Spectrum and Absorption Redshift DATE: 05/11/09 08:06:51 GMT FROM: Robert Quimby at U of Texas/ROTSE R. Quimby (U. Texas), D. Fox (PSU), P. Hoeflich (U. Texas), B. Roman, and J. C. Wheeler (U. Texas) report: We observed the optical afterglow (Rykoff et al. GCN 4211) of GRB 051109 (Tagliaferri et al. GCN 4213) with the 9.2m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) beginning November 9, 03:55:40 UT (~2.5 hrs after the burst trigger). Several absorption lines are present in the spectrum corresponding to Si II (1526.7), C IV, Cr II (2056.3, 2066.2), and Fe II (2344.2, 2382.8) among others at a redshift of z=2.346. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4222 SUBJECT: GRB 051109B: Swift detection of a burst DATE: 05/11/09 09:35:58 GMT FROM: Scott Barthelmy at NASA/GSFC G. Tagliaferri (INAF-OAB), S. Barthelmy (GSFC), D. Burrows (PSU), S. Campana (INAF-OAB), M. Chester (PSU), N. Gehrels (GSFC), T. Mineo (INAF-IASF PA), K. Page (U Leicester), D. Palmer (LANL), T. Sakamoto (GSFC) on behalf of the Swift team: At 08:39:39 UT, Swift-BAT triggered and located GRB 051109B (trigger=163170). The BAT on-board calculated location is RA,Dec 345.440d,+38.672d {23h 01m 46s,+38d 40' 20"} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve shows a multi-peak structure with a total duration of ~20 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. The S/C slewed immediately and the XRT began observations at 08:41:06 UT (86 seconds after the BAT trigger) in auto state. The on-board detection algorithm failed to find a centroid, although the lightcurve suggests a faint source. More information will be available after the next Malindi pass. UVOT began observing at 08:41:03 UT, 84 sec after the BAT trigger. The on-board source detection algorithm reports an uncataloged source at RA=345.46 {23h 01m 50.40s}, DEC=+38.66 {38d 39' 36.0"}, 76 arcsec from the BAT position, with V magnitude 18.4 +/-0.1, in a 200 sec observation covering the BAT error circle. V-band extinction in the direction of the BAT position is A_V = 0.55. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4224 SUBJECT: GRB 051109B Kiso optical follow-up observation DATE: 05/11/09 11:45:03 GMT FROM: Yuji Urata at RIKEN H. Mito, Y. Nakada(Tokyo Univ.), H. Nakanishi(NAOJ), F. Egusa, S. Komugi(Tokyo Univ.), K. Huang(IANCU), Y. Urata(RIKEN) on behalf of EAFON report: "We have imaged entire error region of GRB051109B(Tagliaferri et al. GCN 4222, Swift trigger=163170) using Kiso 1.05m Schmidt telescope. After end of twilight, we have started B and R band observations at 09:12:07 (UT). Comparison with DSS images and USNO-B catalog, there is no new source brighter than B=20.9, R=20.2. There is also no significant signals at the UVOT position reported by Tagliaferri et al (GCN 4222). ========================================== Delay time(min) Filter Limiting mag.(SN=3) 32.5 R 20.2 45.7 B 20.9 ========================================== This message may be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4225 SUBJECT: GRB 051109B: Super-LOTIS Observations DATE: 05/11/09 12:08:22 GMT FROM: Peter A. Milne at Super-LOTIS P.A.Milne, G.G.Williams (Steward Obs), H.-S.Park (LLNL), S.A. Barthelmy (GSFC) on behalf of the Super-LOTIS GRB team report: The automated 0.6-m Super-LOTIS telescope began observations of the error region of GRB051109B (Swift trigger 163170) at 08:40:35.3 UT, 56 seconds after the burst. We obtained a series of images in the R filter. The field was at high airmass (at least secz=2.36), with thin clouds. The source reported by the SWIFT/UVOT (Tagliaferri et al., GCN4222) is not apparent in the first 10 second image (limiting magnitude ~ 17.0), nor in subsequent co-added images. Further analysis of the complete observing sequence is on-going. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4226 SUBJECT: GRB051109B: XRT position DATE: 05/11/09 12:23:53 GMT FROM: Gianpiero Tagliaferri at OAB-INAF S. Campana (INAF-OAB), T. Mineo (INAF-IASF PA), P. Romano (INAF-OAB), G. Tagliaferri (INAF-OAB), D.N. Burrows (PSU) report on behalf of the Swift/XRT team: The Swift XRT began observing GRB 051109B (trigger #163170, Tagliaferri et al., GCN 4222) at 08:41:06 UT, but was unable to obtain an on-board centroid. Analysis of the initial ground-processed data finds a faint and uncataloged source at coordinates: RA(J2000) = 23 01 50.35 Dec(J2000) =+38 40 49.6 We estimate an uncertainty of 4 arcseconds (90% containment), including corrections for the XRT boresight offset. This position lies 60 arcseconds from the BAT position and at 74 arcsec from the UVOT position, respectively, reported in GCN 4222. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4227 SUBJECT: GRB 051109a: BOOTES R & I-band detection of the early afterglow DATE: 05/11/09 12:52:27 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia M. Jelínek, A. de Ugarte Postigo, A. J. Castro-Tirado, S. Vitek, J. Gorosabel, S. B. Pandey and S. S. Guziy (IAA-CSIC Granada), P. Kubanek (ISDC Versoix, and ASU AV CR Ondrejov) and R. Hudec (ASU AV CR) report: "BOOTES-1B in El Arenosillo (southern Spain), responded to the GRB 051109a trigger (Tagliaferri et al. GCNC 4213). A sequence of exposures started at 01:13:15.3 UT (54.8s after the GRB, 27s after the GCN notice), simultaneously in the R and I-bands. We detect the optical afterglow first reported by Rykoff et al. (GCNC 4211) in both passbands. The approximate magnitude on the first 10s R-band image is 16.2 calibrated against USNO-A2.0. Further analysis is in progress." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4228 SUBJECT: GRB051109A: XRT refined analysis DATE: 05/11/09 13:40:11 GMT FROM: Sergio Campana at INAF-OAB S. Campana (INAF-OAB), T. Mineo (INAF-IASFPA), G. Tagliaferri (INAF-OAB), V. Mangano (INAF-IASFPA), P. Romano (INAF-OAB), D.N. Burrows (PSU) on behalf of the Swift/XRT team: We have analysed 10 ks of XRT observations of GRB051109 (Tagliaferri et al., GCN 4213). The afterglow is bright and well detected. The refined coordinates for this X-ray afterglow are: RA(J2000): 22 01 15.3 Dec(J2000): +40 49 24 with an estimated uncertainty of 3.5 arcsec (90% containment) and including the latest XRT boresight correction. The position is 3.2 arcsec from the on-board position reported by Tagliaferri et al. (and 1.2 arcsec from the one by UVOT, ibid.) and 0.9 arcsec from the optical afterglow first detected by ROTSE (Rykoff et al., GCN 4211). The X-ray light-curve shows a clear break between the first and the second Swift orbit (close to the end of the first orbit). In the first part the decay is very steep with index alpha_1=-3.1 +/- 0.6 (90% containment) whereas in the second part it flattens to alpha_2=-0.6 +/- 0.2. The spectrum of the full data (WT and PC) can be modelled with a power-law with photon index Gamma = 2.07 +/- 0.08 (90% containment). There is evidence for an absorbing column higher than the Galactic value (1.9e21 cm^-2) at a level of (8.2+/-5.2)e21 cm^-2 at the observed redshift z=2.346 (Quimby et al., GCN 4221). At 150 s the 0.5-10 keV unabsorbed flux was 3.2e-10 erg cm^-2 s^-1. At 5000 s the afterglow had faded to flux level of 2.4e-11 erg cm^-2 s^-1. Assuming the currect decay (which is very flat) we predict a flux of ~5e-12 erg cm^-2 s^-1 at 1 d from the burst. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4229 SUBJECT: GRB051109A: further steepening in the X-ray light curve DATE: 05/11/09 16:49:51 GMT FROM: Sergio Campana at INAF-OAB S. Campana (INAF-OAB), T. Mineo (INAF-IASFPA), G. Tagliaferri (INAF-OAB), V. Mangano (INAF-IASFPA), P. Romano (INAF-OAB) on behalf of the Swift/XRT team: After the analysis of the full initial dataset, we see that the light curve of GRB051109A shows a further break besides the one already highlighted previously (Campana et al., GCN 4228). This second break is relatively unconstrained occurring between the first (<200 s) and the second (>3000 s) Swift orbit. In the first part the decay is very steep with index alpha_1=-3.1 +/- 0.6 (90% containment, as reported). The second power law contains basically no data and it is only loosely constrained. The third power law has alpha_3=-1.2 +/- 0.1. The reduced chi2 is 1.2 (57 dof). The expected flux at 1 day is 8e-13 erg cm^-2 s^-1. [GCN_OPS_NOTE(09nov05): Per author's request, the Subject line was changed from "050911A" to "051109A".] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4230 SUBJECT: GRB 051109A : Lulin BVRI Optical afterglow observation DATE: 05/11/09 17:49:22 GMT FROM: Yuji Urata at RIKEN GRB 051109A : Lulin BVRI Optical afterglow observation F.Y. Huang, K.Y. Huang, W.H. Ip (NCU), Y. Urata(RIKEN), Y. Qiu (BAO), Y.Q. Lou (THCA) on behalf of EAFON report: "We have observed GRB 051109A afterglow (Rykoff et al. GCN4211) using Lulin 1-m telescope from 9.59 to 13.34 hours after ther burst. The afterglow was detected in our B,V,R,I band images. The R band magnitude of afterglow at 10.97 UT is estimated as R=20.3 calibrated against USNO-B1.0 catalog. Further analysis is in progress. This message may be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4231 SUBJECT: GRB 051109B : Lulin Optical Observations DATE: 05/11/09 17:49:40 GMT FROM: Yuji Urata at RIKEN GRB 051109B : Lulin Optical Observations F.Y. Huang, K.Y. Huang, W.H. Ip (NCU), Y. Urata(RIKEN), Y. Qiu (BAO), Y.Q. Lou (THCA) on behalf of EAFON report: "The R and V band images of GRB 051109B (Tagliaferri et al. GCN 4222) were taken by Lulin 1-m telescope. The observation are started at 1.51 hours after the burst. No new source was detected at Swift/UVOT position (Tagliaferri et al. GCN 4222) and Swift/XRT (Campana et al. 4226) error regions. Compare with USNOB1.0 stars, the limiting magnitudes of our R and V band co-add images (300s x 3 for each band) are estimated as 21.0 and 20.0, respectively. This message may be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4232 SUBJECT: GRB051109B: XRT refined analysis DATE: 05/11/09 18:42:43 GMT FROM: Gianpiero Tagliaferri at OAB-INAF G. Tagliaferri (INAF-OAB), S. Campana (INAF-OAB), P. Romano (INAF-OAB), T. Mineo (INAF-IASFPA), D.N. Burrows (PSU) report on behalf of the Swift/XRT team: We have analysed 4.3 ks of XRT observations of the afterglow of GRB051109B (Tagliaferri et al., GCN 4222; Campana et al. GCN4226). The X-ray light-curve from 100s after the burst up to about 10 ks after the burst is quite flat and well represented by a single power law with a decay index alpha=-0.55+/-0.08 (90% containment). The spectrum can be modeled with a power-law with photon index Gamma = 2.33+/-0.30 (90% containment). There is evidence for an absorbing column higher than the Galactic value (1.3e21 cm^-2) at a level of (3.1+/-1.2)e21 cm^-2. At 200 s the 0.5-10 keV unabsorbed flux was 1.7e-10 erg cm^-2 s^-1. At 10000 s the afterglow had faded to flux level of 2.0e-12 erg cm^-2 s^-1. Assuming the current flat decay we predict a flux of ~5.6e-13 erg cm^-2 s^-1 at 1 d from the burst. [GCN_OPS_NOTE(10nov05): Per author's request, the flux level in the last paragraph "2.0e-11" was changed to "2.0e-12".] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4233 SUBJECT: GRB051109B: no UVOT source detected DATE: 05/11/09 18:44:19 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (UCL-MSSL), G. Tagliaferri (INAF-Brera), A.J. Blustin (UCL-MSSL), D. Hinshaw (GSFC-SPSYS), M. Carter (UCL-MSSL), N. Gehrels (GSFC) on the behalf the UVOT/Swift Team: The Swift UVOT began observing the field of GRB051109B at 08:41:03 UT, 84 seconds after the BAT Trigger (Tagliaferri et al, GCN 4222). No new source with respect to USNO B1.0 is detected within the 4 arcsecond radius XRT error circle (Campana et al., GCN 4226), either in the first exposure or in the coadded V-band exposures down to the following 3 sigma magnitude upper limits: Filter T_range (sec) Exp (sec) 3sigUL V 84-284 200 18.9 V 84-8280 4956 20.8 The source previously reported in GCN 4222 was actually an artefact of the onboard processing and was not a real source. These values are not corrected for Galactic extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4235 SUBJECT: GRB 051109A: Swift-UVOT Observations DATE: 05/11/09 19:55:43 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC GRB 051109A: Swift-UVOT Observations S. T. Holland (GSFC/USRA), S. Campana (INAF-OAB), P. Smith (UCL/MSSL), H. Huckle (UCL/MSSL), & N. Gehrels (GSFC) on behalf of the Swift-UVOT team report: The Swift-UVOT began observing the field of GRB 051109A (BAT Trigger 163136; Palmer, et al. GCN Circular 4213) at 2005-11-09T01:14:09, 109 seconds after the burst. We detect an optical transient at RA(J2000) = 22:01:15.32 Dec(J2000) = +40:49:23.7 with a positional uncertainty of +/-0.5 arcsec (90% confidence), in agreement with the position of Rykoff, et al. (2005, GCN Circular 4211). The transient has V = 16.49 +/- 0.07 (1-sigma, statistical) in an 89 s exposure starting at 2005-11-09T01:14:23, 123 seconds after the BAT trigger. This value supercedes the approximate magnitude given in Palmer, et al. (2005, GCN Circular 4213). This magnitude has not been corrected for Galactic extinction. Further observations and analysis are underway. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4236 SUBJECT: GRB 051109B: ROTSE-III Optical Limits DATE: 05/11/09 20:35:40 GMT FROM: Wiphu Rujopakarn at U Michigan/ROTSE W. Rujopakarn (U Mich), E.S. Rykoff (U Mich), F. Yuan (U Mich) report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 051109B (Swift trigger 163170), producing images beginning 9.1 s after the GCN notice time. An automated response took the first image at 08:40:29.1 UT, 50.7 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 50 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma error circle, for both single images and coadding into sets of 10. We also note that we found no new object within the error circle of XRT position given by Campana et al. (GCN 4226). Individual images have limiting magnitudes ranging from 15.8-17.8; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 08:40:29.1 08:40:34.1 5 16.8 49.8 N 08:40:29.1 08:41:51.1 82 18.0 49.8 Y 08:41:51.4 08:44:50.4 299 17.4 132.1 Y [GCN_OPS_NOTE(10nov05): Per author's request, the 'mlim' for the last entry in the table was changed from 17.4 to 18.5.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4237 SUBJECT: GRB 051109B: Swift-BAT refined analysis DATE: 05/11/09 21:44:23 GMT FROM: Takanori Sakamoto at NASA/GSFC D. Hullinger (UMD), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hinshaw (GSFC-SPSYS), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), P. Meszaros (PSU), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC), on behalf of the Swift-BAT team: Using the data set from T-300 to T+300 sec from the recent telemetry downlink, we report further analysis of BAT GRB 051109B (trigger #163170) (Tagliaferri, et al., GCN 4222). The BAT ground-calculated position is (RA,Dec) = 345.468, +38.666 {23h 1m 52.3s, 38d 39' 58"} [deg; J2000] +-2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 90%. The light curve has a single peak. There is no strong emission in the 100-350 keV band. T90 (15-350 keV) is (15 +- 1) sec (estimated error including systematics). The power law index of the time-averaged spectrum is 1.96 +- 0.25. The fluence in the 15-150 keV band is (2.7 +- 0.4) x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T0+0.24 sec in the 15-150 keV band is (0.5 +- 0.1) ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4238 SUBJECT: Konus-Wind observation of GRB 051109A DATE: 05/11/09 23:00:13 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team report: The long soft GRB 051109A (Swift-BAT trigger #163136; Tagliaferri et al., GCN 4213, E. Fenimore et al., GCN 4217) triggered Konus-Wind at T0= 4342.541 s UT (01:12:22.541). As observed by Konus-Wind it had a single pulse with a duration about ~11 sec and a long decaying tail. This tail was seen up to ~130 sec after T0. The preliminary analysis of the Konus-Wind data gave the burst fluence 4.0(-3.4, +0.3)10^-6 erg/cm2,and peak flux on 256-ms time scale 5.8(-4.9, +0.3)10^-7 erg/cm2/sec (both in the 20 - 500 keV energy range). These values are very uncertain due to weakness and softness of the burst. The K-W spectrum integrated over the most intense part of the GRB (from T0 to T0+8.448 s) is well fitted (in the 20 - 500 keV range) by a power law with exponential cutoff model: dN/dE ~ E^(-alpha) * exp(-E/E0) with alpha = 1.25 (-0.59, +0.44) and E0 = 213 (-126, +246) keV (chi^2 = 56/56 dof). The peak energy Ep = 161 (-58, +224) keV. All the quoted errors are at the 90% confidence level. Assuming z = 2.346 (Quimby et al., GCN 4221) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.3, Omega_\Lambda = 0.7, the isotropic energy release is E_iso ~5x10^52 erg, the maximum luminosity is (L_iso)_max ~2.4x10^52 erg/s. Further analysis and refinement is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4239 SUBJECT: Early RAPTOR measurements of GRB 051109a - the movie. DATE: 05/11/10 00:37:54 GMT FROM: Przemyslaw R. Wozniak at LANL P.R. Wozniak, W.T. Vestrand, J. Wren, R. White, S. Evans on behalf of the RAPTOR team report: Starting at 01:12:54.42 UT on November 9, 33.9 seconds after the Swift BAT trigger, the Raptor-S robotic telescope at Los Alamos National Laboratory responded to Swift trigger 163136 (Tagliaferri et al., GCN 4213). The automated response was composed of a series of ten 5-second duration exposures followed by 20 10-second exposures and finally by 183 30-second exposures. The unfiltered images show an optical transient at the position identifed by Rykoff et al. (GCN 4211) that fades from magnitude R ~15.1 to ~17.5 over the course of 20 minutes. The unfiltered magnitudes were transformed to the R2 magnitude scale of the USNO B1.0 catalog. Short animations derived from the RAPTOR images can be viewed at: EPISODE I: "The First Four Minutes" http://www.raptor.lanl.gov/images/GRB051109a/grb051109a_early_movie.gif EPISODE II: "The Next Half Hour" http://www.raptor.lanl.gov/images/GRB051109a/grb051109a_late_movie.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4240 SUBJECT: GRB 051109A: KAIT optical observations DATE: 05/11/10 05:42:17 GMT FROM: Weidong Li at UC Berkeley KAIT/LOSS W. Li, University of California, Berkeley, on behalf of the KAIT GRB team, report: We remotely observed GRB 051109A (Tagliaferri et al., GCN 4213) with the 0.76-m Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory, and detected the afterglow (Rykoff et al., GCN 4211) in a series of unfiltered exposures. The following photometry are measured (calibrated to the USNO B1.0 catalog): Start UT Exp(s) mag err 2005-11-09 02:25:48 120.0 18.67 0.04 2005-11-09 02:28:28 120.0 18.73 0.06 2005-11-09 02:31:05 240.0 18.75 0.05 2005-11-09 02:35:37 240.0 18.82 0.04 2005-11-09 02:40:14 360.0 18.80 0.04 2005-11-09 02:46:48 360.0 18.88 0.04 2005-11-09 02:53:27 600.0 18.93 0.04 Within this period (74.5 to 106.1 minutes after the burst), the afterglow declined with a power-law decay index of -0.62 +/- 0.07, consistent with the result resported by Mirabal et al. (GCN 4215). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4241 SUBJECT: GRB 051109b: GETS observation DATE: 05/11/10 08:38:00 GMT FROM: Kenzo Kinugasa at Gunma Astro. Obs/Japan K. Kinugasa (Gunma Astronomical Observatory) and K. Torii (Osaka U.) report: The error region of GRB 051109b (Tagliaferri, et al. GCN 4222) was imaged by the robotic 0.25m GETS telescope in the Gunma Astronomical Observatory. Unfiltered imaging started at 08:52:45 UT (13.1 minutes after the trigger) and 30 s integration was repeated. We do not identify a new object within the BAT error region (Hullinger, et al. GCN 4222) and the following 3-sigma upper limits are derived relative to USNO-A1.0 R mag. ------------------------------------------ StartUT Limit Nframes ------------------------------------------ 08:52:45 >18.7 20 09:06:33 >18.7 20 09:35:32 >18.4 30 ------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4243 SUBJECT: GRB051109A - radio observations DATE: 05/11/10 10:21:05 GMT FROM: Guy Pooley at MRAO, Cambridge, UK Guy Pooley, MRAO, Cavendish Lab, University of Cambridge reports: The Ryle Telescope (Cambridge, UK) was used to map the field containing GRB051109A (GCN 4211) at 15GHz. The observation ran from 2005Nov09 12h57m to 2005Nov10 00h54m, centred 17h45m after the initial detection. No source was detected at the position of the GRB (Rykoff et al, GCN 4211; Holland et al, GCN 4235); the formal value was S = 0.40 mJy with rms noise 0.16 mJy. When the data were divided into two halves, the resulting estimates of flux density were First half (centred on 2005Nov09.75) 0.25 +- 0.23 mJy Second half (centred on 2005Nov10.25) 0.54 +- 0.23 mJy //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4244 SUBJECT: GRB 051109A DATE: 05/11/10 19:04:56 GMT FROM: Dale A. Frail at NRAO Dale A. Frail (NRAO), P. Brian Cameron (Caltech), and Alicia M. Soderberg (Caltech) report on behalf of a larger collaboration: "We observed the field of GRB 051109A (GCN 4213) with the Very Large Array at 8.5 GHz around November 11.15 UT. At the position of the optical transient (GCN 4211) there is a weak radio source with flux density 117 ± 24 uJy. We identify this as the radio afterglow of GRB 051109A. 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: 4245 SUBJECT: GRB 051109B. Radio Observations DATE: 05/11/10 19:06:18 GMT FROM: Dale A. Frail at NRAO Dale A. Frail (NRAO), Alicia M. Soderberg (Caltech), and P. Brian Cameron (Caltech) report on behalf of a larger collaboration: "We observed the field of GRB 051109B (GCN 4222; GCN 4237) with the Very Large Array at 8.5 GHz around November 11.15 UT. There is no radio source at the XRT position (GCN 4226; GCN 4232), with a limit of 25 ± 23 uJy. Within the ±2.0 arcmin BAT error radius GCN 4237) we find one radio source at RA(J2000)=23 01 52.77, DEC(J2000) = +38 41 47.9, with (conservative) astrometric errors of order 0.5 arcsec. This is likely a background radio source, unrelated to the GRB. No 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: 4259 SUBJECT: GRB 051109A Optical Observations DATE: 05/11/11 12:26:41 GMT FROM: Kuntal Mishra at ARIES,Nainital,India Kuntal Misra (ARIES, Nainital), Atish P. Kamble (Raman Research Institute, Bangalore), D. K. Sahu, S. Srividya, P. Bama, G.C. Anupama and Mr. S. Vanniarajan (Indian Institute of Astrophysics, Bangalore) on behalf of a larger Indian GRB collaboration We observed the field of GRB 051109A (swift trigger=163136) using the 1-m Sampurnanand Telescope (ST) at ARIES, Naini Tal in Cousins R and I filters and the 2-m Himalayan Chandra Telescope (HCT), IAO, Hanle in Bessell B and V filters, starting nearly 12 hours after the burst. The Optical Transient (OT) mentioned by Rykoff et al. (GCN 4211) is clearly seen in images of 10 minutes exposure time. The preliminary magnitude of the OT in different bands in comparison to 5 nearby USNO-B1.0 stars is: UT Magnitude error Band Telescope used Nov 09.5681 19.449 0.08 I ST Nov 09.5796 20.715 0.09 R ST Nov 09.5463 22.044 0.09 B HCT The OT decayed by ~ 0.6 mag from Nov 09.5681 to Nov 09.7201 UT in R band and by 0.28 mag in B in ~2.4 hrs. Further analysis is in progress. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4265 SUBJECT: GRB 051109A Milagro GeV/TeV Observations DATE: 05/11/11 22:18:05 GMT FROM: Pablo Saz Parkinson at UCSC/Milagro Pablo Saz Parkinson (UC Santa Cruz) on behalf of the Milagro collaboration reports: We have searched Milagro data for emission at GeV/TeV energies from GRB 051109A (GCN Circ 4213, G. Tagliaferri et al.), during the burst duration (36 s) reported by the Swift team (GCN Circ 4217, E. Fenimore et al.). No evidence for prompt GeV/TeV emission was found. A preliminary analysis, assuming a differential photon spectral index of -2.4, gives an upper limit on E^2dN/dE at 99% confidence of: E^2dN/dE at 2.5 TeV < 8.4 * 10^(-8) erg cm^(-2) (No EBL absorption assumed) The spectrum of the host galaxy of the proposed afterglow of GRB 051109A implies a redshift of 2.346 (GCN Circ 4221, R. Quimby et al.). TeV photons are attenuated by pair production with infrared photons in intergalactic space so we also calculate upper limits assuming different extragalactic infrared background light (EBL) absorption models, one by Kneiske et al. 2004 (A&A 413, 807) and one by Primack et al. 2005 (AIP Conf. Proc. 745, p. 23). We find 99% confidence level upper limits on E^2dN/dE of: E^2dN/dE at 55 GeV < 1.7 * 10^(-3) erg cm^(-2) (Primack et al. EBL model) E^2dN/dE at 60 GeV < 2.3 * 10^(-4) erg cm^(-2) (Kneiske et al. EBL model) The energies quoted represent the approximate median energy of the events that would be detected assuming a power law spectrum with differential index -2.4 convolved with each of the absorption models. These upper limits are preliminary and will be refined with further analysis. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4273 SUBJECT: GRB051109A optical observations DATE: 05/11/15 06:34:42 GMT FROM: Vasilij Rumjantsev at CrAO E. Pavlenko (CrAO), K. Berezovsky (óSAS), V.Rumyantsev (CrAO), A.Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed GRB051109A afterglow (Rykoff et al. GCN4211) with 0.38-m telescope in R band on Nov.9 between 15:51 and 17:34 (UT). Preliminary photometry of a stacked image against of USNO A2.0 is following: Mid time, Exposure, Filter, Mag. (UT) (s) Nov. 9 16:43 120x50 R 20.7 +/- 0.2 The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4277 SUBJECT: GRB 051109B : Nainital upper limits DATE: 05/11/16 14:55:42 GMT FROM: Kuntal Mishra at ARIES,Nainital,India Atish P. Kamble (Raman Research Institute, Bangalore) and Kuntal Misra (ARIES, Nainital) on behalf of a larger Indian GRB collaboration We observed the field of GRB 051109B (GCN 4222; GCN 4237) with the 1m Sampurnanand Telescope at ARIES, Nainital in Rc band on November 09 between 18:53 UT and 19:13 UT. There is no new source seen at the XRT position (GCN 4226; GCN 4232). We put the upper limit of Rc > 21.5 at 0.4331 day after the GRB using nearby USNO-B1.0 stars. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4295 SUBJECT: GRB 051109A : GAO 150cm telescope Rc-band detection DATE: 05/11/22 06:10:34 GMT FROM: Kenzo Kinugasa at Gunma Astro. Obs/Japan K. Kinugasa (Gunma Astronomical Observatory) and K. Torii (Osaka U.) report: The error region of GRB 051109A (Tagliaferri et al. GCN 4213) was imaged by the LN2 cooled CCD camera atattched on the 150 cm telescope of the Gunma Astronomical Observatory. Starting at 2005 November 9, 14:56 UT (0.57 days after the burst), nine 30 s and five 180 s exposures in Rc band were obtained. In a stacked frame, the optical afterglow (Rykoff et al. GCN 4211) is detected as follows, relative to USNO-B1.0 R2 magnitude. ------------------------ MidUT Filter Mag ------------------------ 15:08 Rc 20.5 ------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4296 SUBJECT: GRB 051109B: GAO 150cm telescope Optical limit DATE: 05/11/22 06:13:34 GMT FROM: Kenzo Kinugasa at Gunma Astro. Obs/Japan K. Kinugasa (Gunma Astronomical Observatory) and K. Torii (Osaka U.) report: The error region of GRB 051109B (Tagliaferri, et al. GCN 4222) was imaged with the LN2 cooled CCD Camera atattched on the 150 cm telescope of the Gunma Astronomical Observatory. Starting at 15:28 UT (6.8 hours after the burst), V, Rc, and Ic frames were acquired. We do not identify an optical counterpart for the X-ray afterglow (Campana, et al. GCN 4226). Following 3-sigma upper limits are derived for the stacked frames relative to USNO-B1.0 magnitudes. --------------------------------- MidUT Filter Mag Exposure --------------------------------- 15:54 Rc >20.2 180s x 5 16:10 Ic >18.4 60s x 10 --------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5387 SUBJECT: GRB 051109B: Bright spiral host galaxy at low redshift DATE: 06/08/02 04:51:03 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley, R. J. Foley, J. S. Bloom and N. R. Butler (UCB) report: On the night of 2006 July 25 (UT), we imaged the field of GRB051109B (GCN 4222) for 630 seconds in g' and 600 seconds in R using Keck I (+ LRIS). There is a bright (R ~ 14.5) spiral galaxy close to the XRT position (GCN 4226), also visible in DSS and other surveys. In our imaging, the galaxy is observed to be a barred spiral of type SBa. The presence of a faint tidal bridge indicates that the galaxy has recently interacted with a neighboring galaxy 60" to the north. Using 25 X-ray sources and 51 DSS sources in the field, we calculate an improved XRT position of RA = 23:01:50.21, dec = +38:40:46.0 (with a 90% uncertainty radius of 2.2", including an estimate of the systematic error.) This position lies inside an outer spiral arm of the galaxy, identifying it as the GRB host. In addition, both our position and the original XRT error circle include a faint optical point-like source at RA = 23:01:50.30, dec = +38:40:46.7 (0.5" uncertainty). We obtained spectroscopy of the host galaxy and optical source the following night. The galaxy is observed to be at a redshift of z = 0.080, and lacks any strong emission features. Spectroscopy of the point source inside the XRT error circle shows no evidence for a nebular-phase supernova; however, there are emission lines indicating active star formation in this region. The offset of the position of the optical source to the galaxy center is 14.1", or 20.9 kpc at the observed redshift. This is the largest offset yet seen in a long GRB in angular or physical scale. Using the 15-150 keV gamma-ray fluence (GCN 4237), E_iso for this GRB is 4.1 x 10^48 ergs, comparable to that observed for GRB980425 but less than that of any other GRB. GRB980425/SN1998bw was also seen in a spiral galaxy at large offset, and also lacked a detected optical afterglow. Given the low redshift of this system, inspection of archival images for the presence or absence of supernova emission is strongly encouraged. We also encourage radio and X-ray observations to look for a late-time afterglow or supernova. Additional information on this GRB, including an image of the field, is available at: http://lyra.berkeley.edu/~dperley/051109b/host.html //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5441 SUBJECT: GRB051109B: Late-time Radio Observations DATE: 06/08/12 19:23:53 GMT FROM: Alicia Soderberg at Caltech A. M. Soderberg (Caltech), D. A. Frail (NRAO) and P. Chandra (UVA/NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration: "We re-observed the field of GRB 051109B (GCN 4222) centered on the revised XRT position (GCN 5387) using the VLA on August 9.5 UT 2006 (t~9 months after the burst) at a frequency of 1.43 GHz. Comparison with our previous VLA observations (GCN 4245) reveals no new sources within the revised XRT error circle. We place a 3-sigma limit of 0.21 mJy. Adopting a redshift of z=0.08 for the putative host galaxy (GCN 5387), this limit corresponds to a radio luminosity 100 times fainter than that observed for GRB 030329 at a comparable epoch (Frail et al. 2003, ApJ, 619, 944). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."