GRB120521C

This page lists all entries on GRB120521C in GRBweb

Summary IPN Swift GCN 13318 GCN 13319 GCN 13320 GCN 13321 GCN 13322 GCN 13323 GCN 13324 GCN 13325 GCN 13329 GCN 13331 GCN 13332 GCN 13333 GCN 13334 GCN 13336 GCN 13337 GCN 13343 GCN 13344 GCN 13348

Summary table
Variable Value Source
T0 23:22:07 UTC GCN_circulars,Swift Det
ra 214.2864° Swift
decl 42.1447° Swift
pos_error 2.07e-04° Swift
T90 26.7 s Swift
T90_start 23:22:07 UTC Swift
fluence 1.10e-06 erg/cm² Swift
redshift 6.0000
T100 26.7 s
GBM_located False
mjd 56068.97369212963 GCN_circulars,Swift Det
IPN table
GRB_name GRB120521C
ra 214.2875°
decl 42.1167°
pos_error 5.00e-02°
redshift 6.0000
Swift table
GRB_name GRB120521C
t_trigger 23:22:07 UTC
ra 214.2864°
decl 42.1447°
pos_error 2.07e-04°
T90 26.7 s
fluence 1.10e-06 erg/cm²
redshift 6.0000
GCN 13318 table
GRB_name GRB120521C
GCN_number 13318
Detection_method Swift Det
t_trigger 23:22:07 UTC
ra 214.2900°
decl 42.1230°
Circular_text TITLE: GCN CIRCULAR NUMBER: 13318 SUBJECT: GRB 120521C: Swift detection of a burst DATE: 12/05/21 23:46:02 GMT FROM: Scott Barthelmy at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and G. Stratta (ASDC) report on behalf of the Swift Team: At 23:22:07 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120521C (trigger=522656). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 214.290, +42.123 which is RA(J2000) = 14h 17m 09s Dec(J2000) = +42d 07' 23" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single FRED structure with a duration of about 20 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 23:23:16.8 UT, 69.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 214.28671, 42.14311 which is equivalent to: RA(J2000) = 14h 17m 08.81s Dec(J2000) = +42d 08' 35.2" with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 72 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 1.05 x 10^20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 7.43e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 76 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. Results from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01. Burst Advocate for this burst is W. H. Baumgartner (wayne 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.)
GCN 13319 table
GRB_name GRB120521C
GCN_number 13319
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 13319 SUBJECT: GRB 120521C: TAROT Calern observatory optical observations DATE: 12/05/22 00:18:05 GMT FROM: Alain Klotz at CESR-CNRS Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report: We imaged the field of GRB 120521C detected by SWIFT (trigger 522656) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 23 min after the GRB trigger. The elevation of the field decreased from 68 degrees above horizon but humidity was higher than 93% until 23 min after the trigger preventing the record of the beginning of the event. We co-added a series of exposures. No OT was found in the XRT error box (Baumgartner et al. GCNC 13318). start stop 23min 37min R > 19.4 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. This message may be cited.
GCN 13320 table
GRB_name GRB120521C
GCN_number 13320
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 13320 SUBJECT: GRB120521C: Liverpool Telescope observations DATE: 12/05/22 00:45:25 GMT FROM: David Bersier at Liverpool John Moores U David Bersier (LJMU) reports on behalf of the Liverpol GRB collaboration: The Liverpool Telescope responded automatically to Swift trigger 522656 (Baumgartner et al, GCN 13318) 11 minutes after the trigger. We do not detect any variable source inside the XRT error circle. A representative upper limit is R=21.5 at 35 minutes after the burst, calibrated with respect to USNO-B.
GCN 13321 table
GRB_name GRB120521C
GCN_number 13321
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 13321 SUBJECT: GRB 120521C - NOT optical limits DATE: 12/05/22 00:56:05 GMT FROM: Annalisa De Cia at U of Iceland A. De Cia (U. of Iceland), A. Sandberg (Oskar Klein Centre), J.Hjorth (DARK), N.R. Tanvir (U. of Leicester) and P. Jakobsson (U. of Iceland) report: We observed the field of GRB 120521C (Baumgartner et al., GCN 13318) with the NOT equipped with MOSCA in the Sloan r and i filters for 10 minutes, starting at 0:09 UT (47 min after the GRB trigger). No significant source was detected at the burst position, down to r > 23.6 mag, calibrated against SDSS stars.
GCN 13322 table
GRB_name GRB120521C
GCN_number 13322
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 13322 SUBJECT: GRB 120521C: WHT optical observations DATE: 12/05/22 01:20:38 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), M. Hrudkova (ING) report for a larger collaboration: "We obtained observations of GRB 120521C (Baumgartner et al. GCN 13318) with the William Herschel Telescope equipped with ACAM in the r and z-bands. Our observations started at 00:01UT, 39 minutes after the burst trigger. We do not detect any afterglow candidates within the XRT error circle. Provisional limits, calibrated against SDSS suggest r>24.0, z>22.5"
GCN 13323 table
GRB_name GRB120521C
GCN_number 13323
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 13323 SUBJECT: GRB 120521C: BOOTES-1 optical observations DATE: 12/05/22 01:53:37 GMT FROM: Javier Gorosabel at IAA-CSIC M. Jelinek (IAA-CSIC), P. Kubanek (IP AS CR), A.J. Castro-Tirado (IAA-CSIC), J. Gorosabel (IAA-CSIC), report on behalf of a larger collaboration: "The 0.3-m robotic telescope at the BOOTES-1 station in south Spain (INTA-CEDEA) responded automatically to GRB 120521C (Baumgartner et al., GCN Circ. 13318), performing clear-band observations on May 21.98180 -- 21.98863 UT (11.7 -- 21.5 minutes post burst). No object is detected within the XRT circle down to R~20.5"
GCN 13324 table
GRB_name GRB120521C
GCN_number 13324
Detection_method Swift-XRT Det
ra 214.2865°
decl 42.1447°
Circular_text TITLE: GCN CIRCULAR NUMBER: 13324 SUBJECT: GRB 120521C: Enhanced Swift-XRT position DATE: 12/05/22 05:33:54 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 2020 s of XRT Photon Counting mode data and 2 UVOT images for GRB 120521C, 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 = 214.28648, +42.14467 which is equivalent to: RA (J2000): 14h 17m 8.76s Dec (J2000): +42d 08' 40.8" 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.
GCN 13325 table
GRB_name GRB120521C
GCN_number 13325
Detection_method correction
Circular_text TITLE: GCN CIRCULAR NUMBER: 13325 SUBJECT: GRB 120521C: PAIRITEL NIR Upper Limits DATE: 12/05/22 05:44:37 GMT FROM: Adam Morgan at U.C. Berkeley A. N. Morgan (UC Berkeley) reports: We observed the field of GRB 120521C (Baumgartner et al., GCN 13318) with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2012-May-22 03h52m27s UT, ~4.5 hours after the Swift trigger. In mosaics (effective exposure time of 1568 s) taken simultaneously in the J, H, and Ks filters, we do not detect any source within the enhanced XRT error circle (Beardmore et al. GCN 13324). post burst t_mid (hr) exp.(hr) filt U. Limit (3 sig) 4.99 0.44 J > 18.5 4.99 0.44 H > 17.6 4.99 0.44 Ks > 16.0 All magnitudes are given in the Vega system, calibrated to 2MASS. No correction for Galactic extinction has been made to the above reported values.
GCN 13329 table
GRB_name GRB120521C
GCN_number 13329
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 13329 SUBJECT: GRB 120521C: MASTER optical limit DATE: 12/05/22 09:26:17 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs 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 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) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Kislovodsk was pointed to the GRB120521C 60 sec after notice time and 715 sec after GRB time at 2012-05-21 23:34:03 UT in two polarizations. We haven't found optical transient within Swift BAT error-box (Baumgartner et al., GCN 13318) . The 5-sigma upper limit has been about 20.0 mag for mean time after trigger 1492s (total exposition 1370s). The direct copy from MASTER DataBase is: Pro.type Date time Exp.time Limit Filt. Tube. Alert 2012-05-21 23:34:03 130 17.7 P| EAST Alert 2012-05-21 23:34:03 130 18.2 P- WEST Alert 2012-05-21 23:34:03 130 18.2 P- WEST Alert 2012-05-21 23:36:45 160 18.6 P- WEST Alert 2012-05-21 23:36:45 160 18.1 P| EAST Alert 2012-05-21 23:39:48 180 18.9 P- WEST Alert 2012-05-21 23:39:48 180 18.4 P| EAST Alert 2012-05-21 23:43:13 180 18.4 P| EAST Alert 2012-05-21 23:43:13 180 19.0 P- WEST Alert 2012-05-21 23:46:37 180 18.3 P| EAST Alert 2012-05-21 23:46:38 180 18.4 P- WEST Alert 2012-05-21 23:50:02 180 18.4 P| EAST Alert 2012-05-21 23:50:02 180 19.1 P- WEST Alert 2012-05-21 23:53:27 180 18.4 P| EAST Alert 2012-05-21 23:53:27 180 19.1 P- WEST Alert 2012-05-21 23:56:57 180 18.4 P| EAST Alert 2012-05-21 23:56:57 180 19.0 P- WEST AddWest 2012-05-21 23:34:03 1370 20.0 P- WEST The message may be cited.
GCN 13331 table
GRB_name GRB120521C
GCN_number 13331
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13331 SUBJECT: GRB 120521C: Swift/UVOT Upper Limits DATE: 12/05/22 11:01:12 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120521C 77 s after the BAT trigger (Baumgartner et al., GCN Circ. 13318). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 13324) 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 77 227 147 >20.9 u_FC 289 539 246 >20.4 white 77 2226 470 >21.7 v 621 2276 194 >19.8 b 546 2201 156 >20.4 u 289 2177 343 >20.7 w1 670 2325 194 >20.4 m2 645 2128 136 >19.9 w2 596 2251 156 >20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).
GCN 13332 table
GRB_name GRB120521C
GCN_number 13332
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13332 SUBJECT: GRB 120521C: Keck Observations DATE: 12/05/22 12:59:03 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech), O. Yaron (Weizmann), Y. Cao, and S. R. Kulkarni (Caltech) report: We observed the position of GRB 120521C (Baumgartner et al., GCN 13318) with the Keck I 10m telescope (+LRIS) starting at 10:39 UT on 2012-05-22. We acquired a total of 1200s of imaging in I-band and 1360s in g-band. Seeing conditions were relatively poor (1.5"). At the position of the enhanced XRT error circle (Beardmore et al., GCN 13324) we clearly identify a extended source in both the g-band and I-band images. It appears to consist of at least two components; a red source at the southern edge of the XRT error circle and a bluer source at the western edge of the error circle. The relation of these sources to each other and to GRB 120521C is not yet clear, but they could represent a host-galaxy merger system, an afterglow superposed on a host, or two unrelated galaxies at different redshifts. The early nondetections of an afterglow (e.g. Klotz et al., GCN 13319; Bersier et al., GCN 13320; De Cia et al., GCN 13321; Levan et al., GCN 13322; Jelinek et al., GCN 13323; Morgan et al., GCN 13325; Gorbovskoy et al., GCN 13329; Oates et al., GCN 13331) are characteristic of a dark burst. Further observations of this event (in particular in the NIR) are encouraged. An image of the field is posted to: http://www.astro.caltech.edu/~dperley/gcn/120521c/120521c.png
GCN 13333 table
GRB_name GRB120521C
GCN_number 13333
Detection_method Swift-BAT Det
ra 214.2880°
decl 42.1440°
Circular_text TITLE: GCN CIRCULAR NUMBER: 13333 SUBJECT: GRB 120521C: Swift-BAT refined analysis DATE: 12/05/22 13:27:34 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), 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-240 to T+962 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120521C (trigger #522656) (Baumgartner, et al., GCN Circ. 13318). The BAT ground-calculated position is RA, Dec = 214.288, 42.144 deg, which is RA(J2000) = 14h 17m 09.1s Dec(J2000) = +42d 08' 39.8" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%. The mask-weighted light curves shows a FRED peak starting at ~T-2 sec, peaking at ~T+1 sec, abd ending at ~T+40 sec. T90 (15-350 keV) is 26.7 +- 4.4 sec (estimated error including systematics). The time-averaged spectrum from T-1.03 to T+31.84 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.73 +- 0.11. The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.02 sec in the 15-150 keV band is 1.9 +- 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/522656/BA/
GCN 13334 table
GRB_name GRB120521C
GCN_number 13334
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13334 SUBJECT: GRB 120521C: Swift-XRT refined Analysis DATE: 12/05/22 13:46:05 GMT FROM: Phil Evans at U of Leicester M.C. Stroh (PSU), D.N. Burrows (PSU), P.A. Evans (U. Leicester), O.M. Littlejohns (U. Leicester), J.P. Osborne (U. Leicester), A. Maselli (INAF-IASFPA), V. Mangano (INAF-IASFPA), A. Melandri (INAF-OAB), J.A. Kennea (PSU) and W.H. Baumgartner report on behalf of the Swift-XRT team: We have analysed 7.2 ks of XRT data for GRB 120521C (Baumgartner et al. GCN Circ. 13318), from 59 s to 29.2 ks after the BAT trigger. The data comprise 101 s in Windowed Timing (WT) mode (the first 8 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 Beardmore et al. (GCN. Circ 13324). The light curve can be modelled with an initial power-law decay with an index of alpha=2.78 (+0.19, -0.17), followed by a break at T+489 s to an alpha of 0.51 (+0.11, -0.10). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.78 (+0.25, -0.16). The best-fitting absorption column is consistent with the Galactic value of 1.0 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 3.9 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 0 (+4.2, -0) x 10^20 cm^-2 Galactic foreground: 1.0 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.78 (+0.25, -0.16) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00522656. This circular is an official product of the Swift-XRT team.
GCN 13336 table
GRB_name GRB120521C
GCN_number 13336
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13336 SUBJECT: GRB 120521C: EVLA 22 GHz Upper Limit DATE: 12/05/22 21:57:19 GMT FROM: Ashley Zauderer at CfA A. Zauderer and E. Berger (Harvard) report on behalf of a larger collaboration: "We observed the position of GRB 120521C (GCN 13318) beginning 2012 May 22.12 (3.6 hours after the burst) with the EVLA. At a mean frequency of 21.8 GHz, we find no significant radio emission within the refined Swift-XRT error circle (GCN 13324) to a 3-sigma limit of ~50 uJy."
GCN 13337 table
GRB_name GRB120521C
GCN_number 13337
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13337 SUBJECT: GRB 120521C: Early Tautenburg limits DATE: 12/05/22 22:17:24 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, B. Stecklum and U. Laux (TLS Tautenburg) report: We observed to position of Swift GRB 120521C (Trigger 522656, Baumgartner et al., GCN 13318) with the TLS 1.34m Schmidt telescope. Conditions were mediocre, with good seeing but bad transparency. Observations were triggered manually and began 28 minutes after the trigger (17 minutes after the alert). We obtained 5 x 60 s images in Rc, 4 x 180 s images also in Rc, and 1 x 600 s each in Z and Ic. The Ic image is affected in depth by passing clouds. At the position of the enhanced X-ray afterglow (Beardmore et al., GCN 13324), we do not detect any source, in agreement with earlier results (Klotz et al., GCN 13319; Bersier et al., GCN 13320; De Cia et al., GCN 13321; Levan et al., GCN 13322; Jelinek et al., GCN 13323; Morgan et al., GCN 13325; Gorbovskoy et al., GCN 13329; Oates et al., GCN 13331). The possible host galaxy (Perley et al., GCN 13332) is not detected. We us the SDSS star at RA, Dec. (J2000) = 14:17:02.836, +42:6:07.62 (214.26181759, 42.10211787, catalog ID 1237661874023500000) as a comparison star. Using the transformations of Lupton (2005), we find Rc = 18.33, Ic = 17.93 and Z = 17.78 for this star. We find the following 2 sigma limiting magnitudes: Time (days) Exposure (s) Filter UL 0.019827 1 x 60 Rc 21.0 0.022275 5 x 60 Rc 21.8 0.027171 1 x 180 Rc 21.5 0.030760 4 x 180 Rc 22.5 0.040247 1 x 600 Z 20.2 0.048757 1 x 600 Ic 19.3 We note that while the non-detections we as well as other telescopes have found point to this being a dark GRB, the X-ray absorption seen by Swift is small. The Keck detection of a possible host galaxy in g' band likely rules out a high-z interpretation, though. No further observations are planned. This message may be cited.
GCN 13343 table
GRB_name GRB120521C
GCN_number 13343
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 13343 SUBJECT: GRB 120521C: EVLA 22 GHz Detection DATE: 12/05/25 15:16:06 GMT FROM: Ashley Zauderer at CfA A. Zauderer and E. Berger (Harvard) report on behalf of a larger collaboration: "We re-observed the position of GRB 120521C (GCN 13318) on 2012 May 23.12 UT (1.15 d after the burst) with the EVLA at 21.8 GHz. Within the enhanced Swift-XRT error circle (GCN 13324) we detect a brightening radio source with a flux density that is about a factor of two above our early 3-sigma limit of 50 uJy (GCN 13336). We conclude that this is the radio afterglow of GRB 120521C. Follow-up observations at multiple frequencies are in progress."
GCN 13344 table
GRB_name GRB120521C
GCN_number 13344
Detection_method Swift-XRT Other
ra 214.2867°
decl 42.1448°
Circular_text TITLE: GCN CIRCULAR NUMBER: 13344 SUBJECT: GRB 120521C: EVLA Localization of Afterglow DATE: 12/05/25 21:39:06 GMT FROM: Ashley Zauderer at CfA A. Zauderer, E. Berger and T. Laskar (Harvard) report on behalf of a larger collaboration: "Further to GCN 13343, we note that the EVLA 21.8 GHz brightening source within the XRT enhanced error circle of GRB 120521C (GCNs 13318, 13324) is located at (J2000): RA: 14:17:08.802 (+/- 0.002) Dec: +42:08:41.22 (+/- 0.02). This position appears to be offset from the two galaxies at the edge of the Swift-XRT error circle based on the image provided by Perley et al. in GCN 13332."
GCN 13348 table
GRB_name GRB120521C
GCN_number 13348
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 13348 SUBJECT: GRB 120521C redshift estimate DATE: 12/05/29 22:22:31 GMT FROM: Nial Tanvir at U.Leicester N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick), A. Cucchiara (UCSC/UCO Lick), D. Perley (Caltech), P. Hirst (Gemini), T. Carroll, T. Kerr, W. Varricatt (JACH), C. Farina, M. Hrudkova (ING), L. Ker (Edinburgh) report on behalf of a larger collaboration: We have combined observations of GRB 120521C (Baumgartner et al. GCN 13318) made using the WHT (Levan et al., GCN 13322), Keck (Perley et al. GCN 13332), UKIRT and Gemini-N telescopes across the optical-IR region in r,i,z,J,H,K. Analysis of further WHT z-band imaging, obtained at 01:54 UT, 2 hours after our initial epoch (Levan et al. GCN 13322) shows a faint source within the XRT error circle. This source is also seen at high confidence in z-band imaging obtained with Gemini-N at 07:03 UT, and photometry shows that it brightened by 0.5 magnitudes over this period, suggesting it is the afterglow of GRB 120521C. This source is only very weakly visible in contemporaneous I-band imaging obtained with Keck (Perley et al. GCN 13332), and this indicates a red colour i-z >2.3 . However, the source is not detected in our initial reductions of the UKIRT WFCAM imaging in JHK, suggesting that z-K < 1.3 (AB, corresponding to f(nu) ~ nu^-beta with beta<1.3). This is indicative of a high-redshift, rather than a highly reddened afterglow. We note that the position of the afterglow candidate in our data matches the radio position reported by Zauderer et al (GCN 13344) within our calibration uncertainty of ~0.3 arcseconds. Gemini-North GMOS spectroscopy was obtained in poor conditions, using the R400 grating centered at 8000 A, giving a wavelength range of approximately 5850-10100 A. Observations (2 x 1800 s) started at 12:03 UT on 23 May 2012. We used the GMOS Nod&Shuffle observing mode to improve skyline subtraction. In the resulting spectrum, a weak trace is seen at the expected location, which is only detected redward of ~8700 A. The absence of any emission bluewards of this wavelength is suggestive of a high redshift of this source, z~6.0. The low signal of the trace precludes detection of absorption lines. Further analysis of the data is ongoing.