//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12046 SUBJECT: GRB 110530A: Swift detection of a burst with an optical afterglow DATE: 11/05/30 15:49:56 GMT FROM: Scott Barthelmy at NASA/GSFC P. D'Avanzo (INAF-OAB), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), S. Campana (INAF-OAB), V. D'Elia (ASDC), J. M. Gelbord (PSU), B. Gendre (ASDC), C. Gronwall (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), P. T. O\'Brien (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU), C. A. Swenson (PSU) and T. N. Ukwatta (MSU) report on behalf of the Swift Team: At 15:31:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110530A (trigger=454473). Swift slewed after 11 minutes because of an observing constraint. The BAT on-board calculated location is RA, Dec 282.045, +61.932, which is RA(J2000) = 18h 48m 11s Dec(J2000) = +61d 55' 54" 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 20 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 15:38:16.7 UT, 434.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 282.06718, 61.92861 which is equivalent to: RA(J2000) = 18h 48m 16.12s Dec(J2000) = +61d 55' 43.0" with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 39 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. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 5.65 x 10^20 cm^-2 (Kalberla et al. 2005). UVOT took a finding chart exposure of 150 seconds with the White filter starting 437 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 18:48:16.35 = 282.06814 DEC(J2000) = +61:55:45.1 = 61.92920 with a 90%-confidence error radius of about 0.71 arc sec. This position is 2.8 arc sec. from the center of the XRT error circle. The estimated magnitude is 20.31 with a 1-sigma error of about 0.18. No correction has been made for the expected extinction corresponding to E(B-V) of 0.06. Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12048 SUBJECT: GRB 110530A: MITSuME Akeno Optical Observation DATE: 11/05/30 16:54:31 GMT FROM: Yoichi Yatsu at Tokyo Tech. Y. Yatsu, K.Kawakami, Y. Aoki, K. Tokoyoda, M. Hayashi, S. Song, R. Usui, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed GRB110530A (D'Avanzo et al, GCN12046) with the optical three color (g, Rc, and Ic) CCD camera attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The follow-up observation was started at 15:31:02, ~2min after the BAT trigger. And we detected a very faint object within the XRT error circle in R-band. The measured R-band magnitude is shown below. T0+[s] MID-UT T-EXP[sec] g' Rc Ic ----------------------------------------------------------------------- 125 15:39:42 660 --- 18.84 +/- 0.65 --- ----------------------------------------------------------------------- T0+ : Elapsed time after the burst [sec] T-EXP: Total Exposure time [sec] Photometric results and are listed below. We used GSC2.3 catalog for flux calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12049 SUBJECT: GRB 110530A: Swift-BAT refined analysis DATE: 11/05/30 17:57:42 GMT FROM: Scott Barthelmy at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), P. D'Avanzo (INAF-OAB), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 110530A (trigger #454473) (D'Avanzo, et al., GCN Circ. 12046). The BAT ground-calculated position is RA, Dec = 282.045, 61.953 deg, which is RA(J2000) = 18h 48m 10.8s Dec(J2000) = +61d 57' 11.2" with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 98%. The mask-weighted light curve shows a single pulse starting at ~T-50 sec with a slow rise, peaking at ~T+2 sec, and ending at ~T+15 sec. T90 (15-350 keV) is 19.6 +- 3.1 sec (estimated error including systematics). The time-averaged spectrum from T-4.5 to T+17.4 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.06 +- 0.24. The fluence in the 15-150 keV band is 3.3 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+1.01 sec in the 15-150 keV band is 0.4 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/454473/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12050 SUBJECT: GRB 110530A: MASTER OT observations DATE: 11/05/30 18:08:57 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs K.Ivanov, O. Gres, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Chuvalaev Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M.Kornilov, A.Sankovich Sternberg Astronomical Institute, Moscow State University V.Krushinski, I.Zalozhnich, A. Popov Ural State University, Kourovka A. Tlatov, A.V. Parhomenko, D. Dormidontov,V. Senik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka(Siberia) was pointed to the GRB 110530A (D'Avanzo et al, GCN12046) 12 sec s after notice time and 73 sec after GRB time at 2011-05-30 15:32:15.215 UT. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box. The 5-sigma upper limit has been about 15.2 mag (Polarization + R band). The OT appears at 15:42:14 UT (t_start-t_triger = 673 s, Exp_time=130s). Mag ~18.3 (R). After that we see OT on our images in different filters (R,I,Unfiltered,R+P). 20 min ago (2011-05-30 17:44:42): R ~19.5+-0.5. The reduction is continued. This message may be cited. [GCN OPS NOTE(30may11): Per author's request, the subject line was changed from "110521" to "110530".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12051 SUBJECT: GRB 110530A: Correction to GCN Circ 12050 DATE: 11/05/30 18:13:51 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs Vladimir Lipunov. The GCN Circular N 12050 correct subject is: GRB 110530A: MASTER OT observations I am sorry. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12052 SUBJECT: GRB 110530A: optical observations at Mt. Terskol DATE: 11/05/30 21:51:28 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev, I. Sokolov (Terskol Branch of Institute of Astronomy), Yu. Bronich (IC AMER of NASU), A.Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the optical afterglow of the Swift GRB 110530A (D'Avanzo et al, GCN 12046) with Zeiss-2000 and Zeiss-600 telescopes of Mt.Terskol observatory. Optical afterglow is detected in a stacked images. The photometry is based on the star USNO-B1.0 1519-0265568 (RA=18 48 15.86, Dec=+61 56 15.0) assuming R=16.08 is following UT (mid time), Exposure, Filter, OT 18:00 12 x 30 s R(gunn) 20.32 +/- 0.08 18:58 24 x 150 s R 20.6 +/- 0.2 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12053 SUBJECT: GRB110530A: MITSuME Okayama Optical Observation DATE: 11/05/31 02:34:34 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 110530A (D'Avanzo et al., GCNC 12046) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2011-05-30 15:41:32 UT (~11 min after the burst). We detected the previously reported afterglow (Yatsu et al., GCNC 12048) in Rc and Ic bands. Photometric results and are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Rc_err Ic Ic_err ---------------------------------------------------------------------- 0.06460 17:04:03 5520.0 >20.3 19.8 0.2 19.6 0.2 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12054 SUBJECT: GRB 110530: NOT optical observations DATE: 11/05/31 03:04:40 GMT FROM: Annalisa De Cia at U of Iceland A. De Cia, P. Vreeswijk (U. of Iceland), D. Xu (Weizmann Inst.), J. Telting (NOT) and P. Jakobsson (U. of Iceland) report on behalf of a larger collaboration: We observed the field of D'Avanzo et al. (GCN 12046) with the 2.5m NOT telescope at Roque de los Muchachos Observatory (La Palma, Spain) equipped with ALFOSC, starting at 22:18 UT (6.8h after the burst). The optical afterglow is detected, within the XRT error circle reported by D'Avanzo et al., at R ~ 21.3, calibrated against the USNO-B1.0 1519-0265568 star (R2=16.08) also adopted by Andreev et al. GCN 12052. Preliminary reduction of the subsequent spectroscopic observations does not show any evident absorption lines, given the poor S/N. A rough limit on the source redshift z<2.7 may be placed by the non-detection of Lyman alpha absorption in the spectra. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12055 SUBJECT: GRB 110530A: Enhanced Swift-XRT position DATE: 11/05/31 09:27:07 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 8011 s of XRT Photon Counting mode data and 7 UVOT images for GRB 110530A, 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 = 282.06843, +61.92897 which is equivalent to: RA (J2000): 18h 48m 16.42s Dec (J2000): +61d 55' 44.3" with an uncertainty of 1.4 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: 12056 SUBJECT: GRB 110530A: Xinglong TNT observation DATE: 11/05/31 12:08:30 GMT FROM: L.P. Xin at NAOC L.P. Xin, Y.L. Qiu, J.Y. Wei, J. Wang, J.S. Deng, C. Wu, X. H. Han on behalf of EAFON report: We began to observe GRB 110530A (D'Avanzo et al, GCN 12046) with Xinglong TNT telescope at 15:33:15(UT), 133 sec after the burst. The optical afterglow is clearly detected in all images. The brightness is 20.7 mag in R band relative to the reference star of Andreev et al. (GCN Circ. 12052) at the mean time of 10000 sec after the burst. More observations are encouraged. This message may be cited. . //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12057 SUBJECT: GRB 110530A: Swift/UVOT Detection of a Fading Afterglow DATE: 11/05/31 14:14:04 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110530A 438 s after the BAT trigger (D'Avanzo et al., GCN Circ. 12046). A fading source consistent with the enhanced XRT position (Evans et al., GCN Circ. 12055) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 18:48:16.40 = 282.06833 (deg.) Dec (J2000) = +61:55:44.9 = 61.92913 (deg.) with an estimated uncertainty of 0.65 arc sec. (radius, 90% confidence). Preliminary detections using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 438 1015 295 20.31 +/- 0.10 white 7070 8315 1042 21.52 +/- 0.21 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.06 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12058 SUBJECT: GRB 110530A: Swift-XRT refined Analysis DATE: 11/05/31 15:02:01 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo (INAF-OAB) reports on behalf of the Swift-XRT team: We have analysed 12 ks of XRT data for GRB 110530A (D'Avanzo et al. GCN Circ. 12046), from 446 s to 43.1 ks after the BAT trigger. The data comprise 29 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 12055). The light curve can be modelled with a power-law decay with a decay index of alpha=0.81 (+0.05, -0.04). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.30 (+0.09, -0.17). The best-fitting absorption column is 2.8 (+/-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 counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.7 x 10^-11 (7.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.8 (+/-0.5) x 10^21 cm^-2 Galactic foreground: 5.6 x 10^20 cm^-2 Excess significance: 9.2 sigma Photon index: 2.30 (+0.09, -0.17) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00454473. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12059 SUBJECT: GRB 110530A: optical observations at Mt. Terskol, second epoch DATE: 11/06/01 20:03:28 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev, I. Sokolov (Terskol Branch of Institute of Astronomy), Yu. Bronich (IC AMER of NASU), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the optical afterglow of the Swift GRB 110530A (D'Avanzo et al, GCN 12046) with Zeiss-2000 telescope of Mt.Terskol observatory On May, 31 between (UT) 21:41-22:11. At the place of optical afterglow we detect extended object (elongated from SE to NW) with brightness R(gunn) ~ 22.7 calibrated against the star USNO-B1.0 1519-0265568 (RA=18 48 15.86, Dec=+61 56 15.0) and assuming R=16.08. Coordinates of South-East part of the extended object are (J2000) 18 48 16.27 +61 55 45.3 which is ~2" apart from position of the optical afterglow (J2000) 18 48 16.39 +61 55 45.16 obtained in our first epoch observations (Andreev et al. GCN 12052). The accuracy of astrometry is about 0.7" in both coordinates. One can suggest the extended object might be a bright host of GRB 110530A. The finding chart can be found at http://grb.rssi.ru/GRB110530A/grb110530_2m110531.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12062 SUBJECT: GRB 110530A: optical observations in Mondy observatory DATE: 11/06/03 20:44:08 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (SAI MSU), E. Klunko (ISTP), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the optical afterglow of the Swift GRB 110530A (D'Avanzo et al, GCN 12046) with AZT-33IK telescope of Sayan observatory (Mondy) on May, 30 between (UT) 16:06:01 - 19:14:06 (i.e. t0+0.0243 d -- t0+0.1549 days after burst trigger). We took several series of 60 s exposures in R. Optical afterglow is detected in single images in the beginning of the observations while in the end we stacked images in 180 - 300 s combined exposures. The photometry is based on the USNO-B1.0 1519-0265568 star (RA=18 48 15.86, Dec=+61 56 15.0) assuming R=16.08. In particular, the photometry UT (mid time), Exposure, Filter, OT 18:04 5x60 R 20.25 +/- 0.06 18:54 5x60 R 20.58 +/- 0.07 coincide with the photometry reported earlier (Andreev et al., GCN 12052). Preliminary light curve can be found at http://grb.rssi.ru/GRB110530A/GRB110530A_AZT33IK_lc.png One can note a non-monotonous light curve decay with possible rebrightening at 0.03 d and 0.53 d and general power law decay index of about 0.9.