//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13305 SUBJECT: GRB 120521B: Swift detection of a burst DATE: 12/05/21 09:24:51 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC), M. M. Chester (PSU), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), B. Gendre (ASDC), D. M. Palmer (LANL), E. Sonbas (NASA/GSFC/Adiyaman Univ.) and G. Stratta (ASDC) report on behalf of the Swift Team: At 09:07:48 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120521B (trigger=522586). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 197.014, -52.746 which is RA(J2000) = 13h 08m 03s Dec(J2000) = -52d 44' 45" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows multiple overlapping peaks with a duration of about 40 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~6 sec after the trigger. The XRT began observing the field at 09:09:47.6 UT, 118.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 197.0100, -52.7548 which is equivalent to: RA(J2000) = 13h 08m 02.41s Dec(J2000) = -52d 45' 17.4" with an uncertainty of 2.5 arcseconds (radius, 90% containment). This location is 32 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 (2.27 x 10^21 cm^-2, Kalberla et al. 2005), with an excess column of 2.2 (+1.94/-1.36) x 10^22 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 1.42e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 127 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. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.45. Burst Advocate for this burst is J. R. Cummings (jayc AT milkyway.gsfc.nasa.gov). 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: 13306 SUBJECT: GRB 120521B: TAROT La Silla observatory optical observations DATE: 12/05/21 10:00:12 GMT FROM: Bruce Gendre at ASDC Gendre B. (ASDC/INAF-OAR), Klotz A. (IRAP-CNRS-OMP), Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report: We imaged the field of GRB 120521B detected by SWIFT (trigger 522586) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile. The observations started 88.8s after the GRB trigger (25.6s after the notice). The elevation of the field decreased from 12 degrees above horizon and weather conditions were poor. In a clean exposure, taken between T0 + 473.1s and T0 + 563.1s, we do not detect any afterglow with a limiting magnitude of R > 17.2. Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=305.4846 lat=+10.0434 and the galactic extinction in R band is 1.2 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited. ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13307 SUBJECT: GRB120521B: Faulkes Telescope South observations DATE: 12/05/21 10:35:22 GMT FROM: David Bersier at Liverpool John Moores U D Bersier, C. Guidorzi, A. Melandri, J. Jalpelj report: The Faulkes Telescope South robotically observed GRB120521B (Swift trigger 522586, Cumming et al, GCN 13305). The first exposure started approximately 240 seconds after the trigger time. Digital image subtraction does not reveal any variable source inside the XRT error circle. We find upper limits in R ~ 22.0 (40 minutes after the burst). [GCN OPS: corrected per GCN 13308.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13308 SUBJECT: Correction to GCN 13307 (GRB120521B) DATE: 12/05/21 10:47:47 GMT FROM: David Bersier at Liverpool John Moores U D. Bersier wishes to apologise for any confusion related to the wrong title of GCN 13307. The GCN Circular reports observations of GRB120521B, not GRB120521A. The title should read: "GRB120521B: Faulkes Telescope South observations". I thank C. Guidorzi for drawing my attention to this mistake. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13309 SUBJECT: GRB 120521B/Fermi Trigger 359284074: early MASTER-ICATE optical limit DATE: 12/05/21 10:49:58 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, D.Denisenko, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, A.Kuznetsov Moscow Lomonosov State University, Sternberg Astronomical Institute, A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnich, A. Popov, A. Bourdanov, A. Punanova Ural Federal University MASTER VWF robotic cameras (400 square degrees, 1 pix = 22 arcsec, http://observ.pereplet.ru) located in Argentina (Observatorio Astronomico Felix Aguilar) was pointed to the Fermi Trigger 359284074 12 sec before Swift notice time and 65 sec after Swift trigger (Cummings et al., GCN Circ 13305) time at 2012-05-21 09:08:53 UT. On our first image (5 sec exposure) we have not found any OT. T_start(UT) T - T_trig MeanTime Exp Limit Coadd? Filter ---------------------------------------------------------------------- 09 08 53 65 s 67.5s 5s 11.5 No Unfiltered 09 08 53 65 s 77.5s 25s 12.4 Yes Unfiltered The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13311 SUBJECT: GRB 120521B: Enhanced Swift-XRT position DATE: 12/05/21 12:07:59 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 809 s of XRT Photon Counting mode data and 1 UVOT images for GRB 120521B, 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 = 197.00990, -52.75479 which is equivalent to: RA (J2000): 13h 08m 2.38s Dec (J2000): -52d 45' 17.2" with an uncertainty of 2.0 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: 13316 SUBJECT: GRB 120521B: Swift-XRT refined Analysis DATE: 12/05/21 21:25:04 GMT FROM: Phil Evans at U of Leicester P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), J.A. Kennea (PSU), M.C. Stroh (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA) and J.R. Cummings report on behalf of the Swift-XRT team: We have analysed 9.1 ks of XRT data for GRB 120521B (Cummings et al. GCN Circ. 13305), from 125 s to 19.4 ks after the BAT trigger. The data comprise 28 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN. Circ 13311). The light curve can be modelled with an initial power-law decay with an index of alpha=5.0 (+0.7, -0.6), followed by a break at T+267 s to an alpha of 0.69 (+/-0.07). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.9 (+0.4, -0.3). The best-fitting absorption column is 1.5 (+0.4, -0.3) x 10^22 cm^-2, in excess of the Galactic value of 2.3 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.6 x 10^-11 (1.4 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.5 (+0.4, -0.3) x 10^22 cm^-2 Galactic foreground: 2.3 x 10^21 cm^-2 Excess significance: 6.2 sigma Photon index: 1.9 (+0.4, -0.3) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00522586. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13317 SUBJECT: GRB 120521B: Swift-BAT refined analysis DATE: 12/05/21 22:48:55 GMT FROM: Scott Barthelmy at NASA/GSFC H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), 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-60 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120521B (trigger #522586) (Cummngs, et al., GCN Circ. 13305). The BAT ground-calculated position is RA, Dec = 197.016, -52.742 deg, which is RA(J2000) = 13h 08m 03.9s Dec(J2000) = -52d 44' 31.9" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 35%. The mask-weighted light curve shows several overlapping peaks starting at ~T-1 sec, with equal-amplitude maximum peaks at ~T+6 and ~T+32 sec, and ending at around T+180 sec. There is a possibility (at the 2-sigma level) that emission continues out past the T+243sec end of the downlinked data. T90 (15-350 keV) is 31.4 +- 4.0 sec (estimated error including systematics). The time-averaged spectrum from T-1.39 to T+35.58 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.97 +- 0.15. The fluence in the 15-150 keV band is 1.5 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+31.04 sec in the 15-150 keV band is 0.9 +- 0.2 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/522586/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13328 SUBJECT: GRB 120521B: GROND Upper limits DATE: 12/05/22 08:24:45 GMT FROM: Sylvio Klose at TLS Tautenburg A. Rossi (TLS Tautenburg), M. Nardini (Universita'degli Studi Milano-Bicocca), S. Klose (TLS Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 120521B (Swift trigger 522586; Cummings et al., GCN 13305) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory (Chile). Observations started at 00:35 UT on 2012-05-22, 15.3 h after the GRB trigger, and lasted for 140 minutes. They were performed with good sky conditions at an average seeing of 0.8" and at an average airmass of 1.05. (At the time of the GRB trigger the field was already too close to the telescope's horizon distance limit in order to observe it with GROND.) Based on an exposure of 37 minutes in the optical and 30 minutes in the NIR we do not detect any source within the Swift-XRT error circle reported by Osborne et al. (GCN 13311). Preliminary observed upper limits (AB mags) are: g' > 24.5 r' > 24.2 i' > 23.9 z' > 23.9 J > 21.3 H > 20.3 Ks > 19.3. These limits are derived based on GROND zeropoints (g'r'i'z') and 2MASS stars (JHK). We note that the Galactic reddening along the line of sight is E_(B-V)= 0.45 mag (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13330 SUBJECT: GRB 120521B: Swift/UVOT Upper Limits DATE: 12/05/22 10:59:58 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and J. R. Cummings (NASA/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120521B 127 s after the BAT trigger (Cummings et al., GCN Circ. 13305). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 13311) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 127 277 147 >19.4 u_FC 286 535 246 >19.4 white 127 30912 2930 >19.8 v 615 23584 2045 >18.7 b 541 36686 2819 >19.7 u 286 36128 2526 >20.2 w1 665 35215 2046 >20.7 m2 5582 24489 1279 >21.0 w2 765 19363 1746 >21.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.45 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13339 SUBJECT: GRB 120521B: Fermi GBM observation DATE: 12/05/23 09:16:58 GMT FROM: David Gruber at MPE David Gruber (MPE) reports on behalf of the Fermi GBM Team: "At 09:07:52.39 UT on 21 May 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 120521B (trigger 359284074 / 120521380). which was also detected by the Swift/BAT (Krimm et al. 2012, GCN 13317) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 84 degrees. The GBM light curve consists of a single pulse with a duration (T90) of about 91 s (50-300 keV). The time-averaged spectrum from T0-5 s to T0+29 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.34 +/- 0.20 and the cutoff energy, parameterized as Epeak, is 213 +/- 29 keV The event fluence (10-1000 keV) over the T90 time interval is (3.11 +/- 0.07)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.4 s in the 10-1000 keV band is 1.55 +/- 0.23 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13342 SUBJECT: GRB120521B: SSO 2.3m upper limits DATE: 12/05/24 09:31:38 GMT FROM: Sharon Rapoport at The ANU S. Rapoport, S. Sweet, J. Scharwachter, B. Schmidt, M. Childress report observations of GRB120521B taken on 2012-05-21.42 UTC (2.7 hours post-alert) using the Wide Field Spectrograph (WiFeS) on the ANU 2.3m, obtaining 3x900s integration at resolution R=3000. Spectral summation of the sky-subtracted data cube in a 3" radius centered at the GRB location shows no detectable optical counterpart to the GRB and no detectable host galaxy. Based on measurement of a nearby field star in the data cube (m_B=18.4, m_R=17.2 -- USNO) we estimate a non-detection upper limit of m_R=20.5 and m_B=20.0 at 5 sigma for the GRB or its host galaxy.