//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12196 SUBJECT: GRB 110726A: Swift detection of a burst DATE: 11/07/26 01:48:27 GMT FROM: Scott Barthelmy at NASA/GSFC C. A. Wolf (PSU), S. D. Barthelmy (GSFC), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), O. M. Littlejohns (U Leicester), C. B. Markwardt (NASA/GSFC), A. Melandri (INAF-OAB), C. J. Mountford (U Leicester), D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC), C. J. Saxton (UCL-MSSL), M. H. Siegel (PSU), E. Sonbas (GSFC/USRA/Adiyaman Univ.), M. Stamatikos (OSU/NASA/GSFC), C. A. Swenson (PSU) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team: At 01:30:40 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110726A (trigger=458059). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 286.751, +56.053 which is RA(J2000) = 19h 07m 00s Dec(J2000) = +56d 03' 12" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 10 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 01:31:38.7 UT, 58.2 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 286.7161, 56.0712 which is equivalent to: RA(J2000) = 19h 06m 51.87s Dec(J2000) = +56d 04' 16.3" with an uncertainty of 2.2 arcseconds (radius, 90% containment). This location is 95 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (5.60 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 1.8 (+1.73/-1.55) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 59 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.08. Burst Advocate for this burst is C. A. Wolf (cwolf AT swift.psu.edu). 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: 12197 SUBJECT: GRB 110726: ROTSE-III Detection of Optical Counterpart DATE: 11/07/26 01:53:46 GMT FROM: Heather Flewelling at IfA/Hawaii GRB 110726A: ROTSE-III Detection of Optical Counterpart B. E. Schaefer (Louisiana State), W. Zheng (U Mich), H. Flewelling (IfA/Hawaii), report on behalf of the ROTSE collaboration: ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe, Turkey, responded to GRB 110726 (Swift trigger 458059). The first image was at 01:31:01.6 UT, 13.8 s after the burst (8.6 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: 19:06:51.98 +56:04:15.03 (J2000), with positional uncertainty of 1' or better start UT mag mlim(of image) ---------------------------------- 01:31:01.6 16.1 16.9 A jpeg image is available at http://www.rotse.net/images/gsq458059_3d00_img.jpg This object is very fast fading. Continuing observations are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12198 SUBJECT: GRB 110726A: Liverpool Telescope observations DATE: 11/07/26 03:37:41 GMT FROM: Andrea Melandri at Liverpool John Moores U A. Melandri (INAF-OAB), D. Bersier and R. Smith (Liverpool JMU) report on behalf of a large collaboration: The 2-m Liverpool Telescope robotically followed up GRB110726A (SWIFT trigger 458059; Wolf et al. GCN 12196) starting 190 seconds after the GRB trigger time. Initial RINGO2 polarimeter frames detected no candidate optical transient. Switching to broad band imaging, we do detect an uncatalogued source inside the XRT error circle, consistent wih the proposed optical counterpart of Schaefer et al. (GCN Circ. 12197), in all three SDSS-gri filters. Our preliminary photometry gives: Mid time from Total Exp Filter Magnitude trigger (min) (s) ------------------------------------------------ 14.7 10 R 19.0 +/- 0.1 30.0 60 R 19.6 +/- 0.1 20.1 30 I 18.6 +/- 0.1 33.0 60 I 19.1 +/- 0.1 ------------------------------------------------ The observed decay is rather shallow (power law index ~0.4) for the next 45 minutes, unlike the initial behavior observed by ROTSE. Magnitudes have been calibrated from the nearby USNOB-1 stars. Observations still ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12199 SUBJECT: GRB 110726A: Swift/UVOT Detection DATE: 11/07/26 04:02:40 GMT FROM: Mike Siegel at PSU/Swift MOC M.H. Siegel (PSU) and C. A. Wolf (PSU) report on behalf of the Swift/UVOT team: Swift/UVOT began observations of the field of GRB 110726A (Wolf et al. 2011, GCN 12196) 59 seconds after the BAT trigger. The 150 second finding chart in the White filter reveals a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at: RA(J2000) = 19:06:52.06 = 286.71693 DEC(J2000) = +56:04:16.6 = 56.0713 with a 90%-confidence error radius of about 0.6 arc sec. This is consistent with the afterglow reported by both the XRT (Wolf et al.) and ROTSE (Schaefer et al., 2011, GCN 12197). The estimated magnitude is 17.80 with a 1-sigma error of about 0.06. No correction has been made for the expected extinction corresponding to E(B-V) of 0.08. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12200 SUBJECT: GRB 110726A: Enhanced Swift-XRT position DATE: 11/07/26 10:30:39 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 629 s of XRT Photon Counting mode data and 1 UVOT images for GRB 110726A, 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 = 286.71752, +56.07123 which is equivalent to: RA (J2000): 19h 06m 52.21s Dec (J2000): +56d 04' 16.4" with an uncertainty of 1.5 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: 12201 SUBJECT: GRB 110726A: Swift-BAT refined analysis DATE: 11/07/26 11:38:19 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU), C. A. Wolf (PSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+572 sec from the recent telemetry downlink, we report further analysis of BAT GRB 110726A (trigger #458059) (Wolf, et al., GCN Circ. 12196). The BAT ground-calculated position is RA, Dec = 286.713, 56.070 deg which is RA(J2000) = 19h 06m 51.2s Dec(J2000) = +56d 04' 11.0" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a single peak starting at ~T-1 sec, peaking at ~T+2 sec, and ending at ~T+5 sec. T90 (15-350 keV) is 5.2 +- 1.1 sec (estimated error including systematics). The time-averaged spectrum from T-0.9 to T+5.0 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.64 +- 0.87, and Epeak of 46.5 +- 11.8 keV (chi squared 79.8 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.2 +- 0.3 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+0.61 sec in the 15-150 keV band is 1.0 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.86 +- 0.18 (chi squared 87.7 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/458059/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12202 SUBJECT: GRB110726A: Gemini-N tentative redshift DATE: 11/07/26 17:19:31 GMT FROM: Antonino Cucchiara at LBNL A. Cucchiara (UC Santa Cruz), J. S. Bloom and S. B. Cenko (UC Berkeley) report on behalf of a larger collaboration: "We observed the field of GRB 110726A at 06:14 UT (~0.19 days after the burst) with the GMOS camera mounted on the Gemini-North telescope. We obtained a sequence of 2x900 seconds spectra centered at 6000 Angstrom and covering 4000-8100A wavelength range. The object is well detected and present a featureless continuum except for a weak double line which we interpret as a signature of MgII 2796,2803 at redshift z = 1.036. No other clear features are detected. Therefore, we suggest 1.036 < z < 2.7 as redshift range for GRB 110726A. We thank the Gemini-N staff for performing this observation, in particular J. Holt."//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12203 SUBJECT: GRB 110726A: Further Swift/UVOT Observations DATE: 11/07/26 19:00:16 GMT FROM: Mike Siegel at PSU/Swift MOC B.L. Porterfield (PSU), M.H. Siegel (PSU) and C.A. Wolf (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110726A 60 s after the BAT trigger (Wolf et al., GCN Circ. 12196). A fading source consistent with the XRT position is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 19:06:52.08 = 286.71700 (deg.) Dec (J2000) = +56:04:16.5 = 56.07126 (deg.) with an estimated uncertainty of 0.51 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the early exposures are listed below. Filter T_start(s) T_stop(s) Exp(s) Mag white fc 60 210 147 17.84 +/- 0.04 white 6348 6520 169 >20.85 v 602 11374 806 20.61 +/- 0.27 b 528 6344 235 20.44 +/- 0.22 u fc 272 522 246 18.41 +/- 0.08 u 5938 17370 1081 >21.25 w1 653 5934 216 >20.5 m2 628 12301 825 >21.1 w2 578 10448 649 >21.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12204 SUBJECT: GRB110726A: MITSuME Ishigakijima Optical Observation DATE: 11/07/27 00:03:12 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (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 110726A (Wolf et al., GCN 12196) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. The observation started on 12:56:13 UT (~11.4 h after the burst). We detected the previously reported afterglow (Schaefer et al., GCN 12197; Melandri et al., GCN 12198) in Rc bands. Photometric results and three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Rc_err Ic ---------------------------------------------------------------------- 0.53142 14:15:55 7020.0 >22.3 21.8 0.2 >20.7 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12205 SUBJECT: GRB 110726A: ROTSE-III refined analysis, fast decay in early phase DATE: 11/07/27 00:49:50 GMT FROM: Weikang Zheng at U.of Michigan W. Zheng (U Mich), B. E. Schaefer (Louisiana State), H. Flewelling (IfA/Hawaii), report on behalf of the ROTSE collaboration: Further analysis to the early optical observations of GRB 110726A from ROTSE-IIId (Schaefer et al. GCN 12197) shows that, the OT decayed quickly in early time after ~140s. The OT is detected in our first co-added of 10 images (14s -142s) with magnitude ~16.1 +/- 0.2. However, in our second co-added of 10 images (150s - 429s), and afterward observations, the OT had faded to below our limiting magnitude of ~18.0, this gives a decay index larger than -1.7, which is much steeper than the later decay index reported by Melandri et al. (GCN 12198) of ~-0.4 15 minutes after the burst. We summarize the result below: t_start t_stop mag err detection? number of co-added images 14.0 74.0 16.1 0.3 Yes 5 82.0 142.0 16.1 0.3 Yes 5 150.0 285.0 17.8 - Upper limit 5 293.0 429.0 17.8 - Upper limit 5 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12206 SUBJECT: GRB 110726A: IAC80 R-band observations DATE: 11/07/27 02:09:41 GMT FROM: Javier Gorosabel at IAA-CSIC J. Gorosabel (IAA-CSIC), D. Jimenez (IAC), A.J. Castro-Tirado (IAA-CSIC), A. de Ugarte Postigo (DARK/NBI), report on behalf of a larger collaboration: "We carried out R-band observations of the GRB 110726A XRT error circle (Osborne et al., GCNC 12200) with the 0.82m IAC80 telescope at the Observatorio del Teide, Tenerife. A single exposure of 600s taken on July 26.19673-26.20367 UT (3.21-3.38 hours post GRB) shows the optical afterglow (Schaefer et al., GCNC 12197) at a preliminary magnitude of R~20.8. We used as photometric reference the R=18.06 USNO B1.0 star 1460-0295684, located at RA(J2000)=19:06:51.534, DEC(J2000)=+56:04:41.20." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12207 SUBJECT: GRB 110726A: EVLA observations DATE: 11/07/27 03:30:03 GMT FROM: Ashley Zauderer at CfA A. Zauderer, E. Berger (Harvard/CfA), and D. A. Frail (NRAO) report on behalf of a larger collaboration: "We observed GRB 110726A (GCN 12196) with the EVLA beginning on 2011 July 26.19 UT (3.1 hours after the burst) at 5.8 GHz. No source is detected in coincidence with the optical counterpart (GCNs 12197,12199) to a 3-sigma limit of about 60 microJy." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12210 SUBJECT: GRB 110726A: optical upper limit in CrAO DATE: 11/07/29 14:38:54 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev, N. Pit (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 110726A (Wolf et al., GCN 12196) with AZT-11 telescope of CrAO between Jul. 26 (UT) 18:48 - 20:13. We do not detect the afterglow (Schaefer et al., GCN 12197; Melandri et al., GCN 12198) . The photometry is based on the star used in GCN 12206 (Gorosabel et al.) USNO B1.0 1460-02955684 (19 06 51.53 +56 04 41.2 ) assuming R=18.06: T0+ Filter, Exposure, OT, Upper Limit (3 sigma) (mid, d) (s) 0.7511 R 29x180 n/d 21.5 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12243 SUBJECT: GRB 110726A: Swift-XRT refined Analysis DATE: 11/08/03 12:34:39 GMT FROM: Chris Wolf at PSU C. A. Wolf (PSU) reports on behalf of the Swift-XRT team: We have analysed 50 ks of XRT data for GRB 110726A (Wolf et al. GCN Circ. 12196), from 47 s to 421.3 ks after the BAT trigger. The data comprise 1.3 ks in Windowed Timing (WT) mode (the first 4 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN. Circ 12200). The late-time light curve (from T0+4.1 ks) can be modelled with a power-law decay with a decay index of alpha=1.26 (+0.16, -0.15). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.12 (+0.22, -0.21). The best-fitting absorption column is 1.6 (+/-0.5) x 10^21 cm^-2, in excess of the Galactic value of 5.6 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.15 (+0.12, -0.28) and a best-fitting absorption column of 9.6 (+3.9, -4.0) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (4.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 9.6 (+3.9, -4.0) x 10^20 cm^-2 Galactic foreground: 5.6 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 2.15 (+0.12, -0.28) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00458059. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12251 SUBJECT: GRB 110726A: two epochs of SAO RAS optical observations DATE: 11/08/06 07:04:37 GMT FROM: Vladimir Sokolov at SAO RAS A.S.Moskvitin, V.V.Sokolov report on behalf of the SAO RAS GRB follow-up team: We observed the field of GRB 110726A (Wolf et al., GCN 12196) with two optical telescopes of SAO RAS: the 1-m Zeiss-1000 on July, 26/27 in B and Rc bands and the 6-m BTA + Scorpio on July, 29/30 in Rc band. We clearly detected an optical transient at the place reported by Schaefer, Zheng & Flewelling (GCN Circ. 12197, ROTSE-III) and Siegel & Wolf (GCN Circ. 12199, Swift/UVOT). Results of SAO RAS observations of OT are presented in the following table. _______________________________________________________________________ date of July, UT filter exp. magnitude telescope _______________________________________________________________________ 26.833 -- 27.017 Rc 17 x 300 sec. 22.17 +/- 0.12 Zeiss-1000 26.856 -- 27.022 B 16 x 300 sec. 23.47 +/- 0.17 Zeiss-1000 29.819 -- 29.861 Rc 15 x 180 sec. 23.34 +/- 0.09 BTA _______________________________________________________________________ We use USNO-B.1 1460-0295684 (R. A. = 19:06:51.53, Dec. = +56:04:41.2, Epoch = 2000.0) with the magnitudes B2 = 20.39, R2 = 18.06 (Gorosabel et al. GCN Circ. 12206) as the reference star. At the BTA image (ftp://ftp.sao.ru/pub/grb/GRB110726A/GRB110726A_BTA.jpeg) we detected one more faint object with R = 25.21 +/- 0.30, located 3.5" North-East from the Swift/UVOT position. According to the Gemini-N redshift range 1.036 < z < 2.7 reported by Cucchiara Bloom & Cenko (GCN Circ. 12202) this angle size corresponds to (110 -- 370) +/- 20 kpc. The message may be cited.