//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10797 SUBJECT: GRB 100526A: Swift detection of a burst DATE: 10/05/26 16:36:06 GMT FROM: David Palmer at LANL L. Vetere (PSU), S. Campana (INAF-OAB), J. R. Cummings (NASA/UMBC), J. M. Gelbord (PSU), D. Grupe (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), W.B Landsman (GSFC), J. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC), J. P. Osborne (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), T. A. Pritchard (PSU), B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU), M. A. Stark (PSU) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team: At 16:26:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100526A (trigger=423181). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 230.785, +25.639 which is RA(J2000) = 15h 23m 08s Dec(J2000) = +25d 38' 20" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for an image trigger, there is no obvious variation in the immediately-available lightcurve. The XRT began observing the field at 16:28:36.0 UT, 145.8 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 230.7684, +25.6310 which is equivalent to: RA(J2000) = 15h 23m 04.41s Dec(J2000) = +25d 37' 51.6" with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 61 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 2.71e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 151 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 0.04. Burst Advocate for this burst is L. Vetere (vetere AT astro.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: 10798 SUBJECT: GRB 100526A: MASTER-Net optical alert observations DATE: 10/05/26 19:02:59 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Yurkov, Yu.Sergienko, D.Varda, A.Garusina Blagoveschensk Educational State University, Blagoveschensk E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina, D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zemnukhov, M. Kornilov Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka K.Ivanov, S.Yazev, N.M.Budnev, E.Konstantinov, V.Lenok Irkutsk State University MASTER robotic telescope (MASTER-Net: http://observ.pereplet.ru, 200 mm, FOV=8 square degrees (testing mode)) and Very Wide Field Camera (D=50 mm, 1000 square degrees, 11 Mpx, 36" per pix, mounted on telescope) located at Blagoveschensk was ponted to the GRB 100526A (L. Vetere et al. gcn 10797) 21 min after burst. For the unknown reason any of our observatories hasn't received socket alert on this burst (we have received only auxiliary packages). We have a number images with 60-s exposition. We haven't found optical transient within Swift-XRT error-box. The 3-sigma unfiltred upper limit has been about 17.0 mag on single and 18.2 mag on 10 images coadd. http://observ.pereplet.ru/images/GRB100526A/grb100526.jpeg The message may be cited. mailto: lipunov@sai.msu.ru //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10800 SUBJECT: GRB 100526A: Enhanced Swift-XRT position DATE: 10/05/26 19:50:41 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 1199 s of XRT Photon Counting mode data and 1 UVOT images for GRB 100526A, 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 = 230.76903, +25.63234 which is equivalent to: RA (J2000): 15h 23m 4.57s Dec (J2000): +25d 37' 56.4" with an uncertainty of 1.7 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: 10801 SUBJECT: GRB 100526A: Swift-BAT refined analysis DATE: 10/05/26 20:11:43 GMT FROM: Scott Barthelmy at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU), L. Vetere (PSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+303 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100526A (trigger #423181) (Vetere, et al., GCN Circ. 10797). The BAT ground-calculated position is RA, Dec = 230.792, 25.623 deg which is RA(J2000) = 15h 23m 10.2s Dec(J2000) = +25d 37' 24.4" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 26%. The mask-weighted light curve shows a few overlapping peaks starting at ~T-70 sec, peaking around T-20 and at ~T+75 sec, and ending at ~T+115 sec. T90 (15-350 keV) is 102 +- 8.5 sec (estimated error including systematics). The time-averaged spectrum from T-33.2 to T+80.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.83 +- 0.17. The fluence in the 15-150 keV band is 2.5 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+69.90 sec in the 15-150 keV band is 0.7 +- 0.3 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/423181/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10804 SUBJECT: GRB 100526A: Swift XRT refined analysis DATE: 10/05/26 22:18:34 GMT FROM: Loredana Vetere at PSU L. Vetere (PSU) reports on behalf of the Swift-XRT team: We have analysed 1.6 ks of XRT data for GRB 100526A (Vetere et al. GCN Circ. 10797), from 151 s to 5.0 ks after the BAT trigger. The data comprise 234 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 10800). The 0.3-10 keV light curve shows a multiple peak structure, with the main spike at about T+200, followed by a fast decay with of alpha=3.24 (+/-0.08), followed by a break at T+732 s to an alpha of 0.8 (+/-0.4). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.97 (+/-0.08). The best-fitting absorption column is 3.21 (+0.18, -0.17) x 10^21 cm^-2, in excess of the Galactic value of 3.8 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.45 (+0.24, -0.22) and a best-fitting absorption column of 1.8 (+0.6, -0.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (5.9 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 0.8, the count rate at T+24 hours will be 0.011 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.7 x 10^-13 (6.7 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00423181. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10805 SUBJECT: GRB 100526A: NOT optical upper limit DATE: 10/05/27 02:36:52 GMT FROM: Dong Xu at DARK,NBI D. Xu (Weizmann Inst.), D. Malesani (DARK/NBI), P. Jakobsson (Univ. Iceland), T. Augusteijn (NOT), A. Thygesen (NOT) report on behalf of a larger collaboration: We observed the field of GRB 100526A (Vetere et al., GCN 10797) with the NOT equipped with ALFOSC in the R and i filters. Observations started on May 26 at 22:43 and 23:10 UT in R and i, respectively (6.282 and 6.742 hr after the GRB), and were affected by the closeby Moon (47 deg away). We do not detect any new object within the refined XRT error circle (Beardmore et al, GCN 10800) in both R and i bands. The limiting magnitude is R(Vega) ~ 23.8, calibrated against the SDSS catalog. [GCN OPS NOTE(27may10): Per author's request, Augusteijn was added to the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10806 SUBJECT: GRB 100526A: Gemini/NIRI infrared afterglow candidate DATE: 10/05/27 11:41:49 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley (UC Berkeley) reports on behalf of a larger collaboration: We imaged the field of GRB 100526A (Vetere et al., GCN 10797) with the Near-InfraRed Imager (NIRI) on Gemini-North starting at 08:29 UT on 2010-05-27. We obtained 18 exposures of 60 seconds each in K-band and H-band. At the edge of the XRT error circle (Beardmore et al., GCN 10800) we clearly detect a source with no SDSS counterpart in the K-band image. It is also present, but much fainter, in H-band. The position (J2000) is: RA = 15:23:04.480 Dec = +25:37:55.23 (+/- 0.4") Preliminary photometry relative to a single 2MASS star in the field (2MASS 1523017+2538260) gives: K = 19.09 +/- 0.13 (t_mid = 16.21 hours) H = 21.15 +/- 0.17 (t_mid = 16.75 hours) This is an extremely red color, corresponding to a spectral slope of beta~5.5. If this object is confirmed as the afterglow (rather than a host or background galaxy), its flux and color are reminiscent of GRB 070306 (Jaunsen et al. 2008) at similar times. That object had a visual extinction of A_V~5.5 mag and is among the most heavily extinguished afterglows known. The large inferred XRT absorption column (Vetere et al., GCN 10804) of this event is also consistent with a highly dust-extinguished event at low to moderate redshift. We thank Richard McDermid and the Gemini staff for acquiring these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10807 SUBJECT: GRB 100526A: Swift/UVOT Upper Limits DATE: 10/05/27 18:23:49 GMT FROM: Tyler Pritchard at PSU T. A. Pritchard (PSU) and Vetere (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100526A 151 s after the BAT trigger (Vetere et al., GCN Circ. 10797). No optical afterglow consistent with the enhanced XRT position (A. P. Beardmore et al.,GCN Circ. 10800) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag -------------------------------------------------------------- white (FC) 151 301 147 >21.1 u (FC) 310 559 246 >20.1 white 151 7321 783 >22.4 v 640 6296 313 >20.3 b 565 7116 491 >21.5 u 310 6911 717 >21.3 w1 690 6706 471 >20.9 m2 4865 6501 393 >20.6 w2 791 7374 263 >20.6 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10818 SUBJECT: GRB 100526A: optical upper limit DATE: 10/06/01 20:17:14 GMT FROM: Alexei Pozanenko at IKI, Moscow D. Shakhovkoy, V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 100526A (Vetere et al. GCN 10797) with AZT-11 telescope of CrAO between (UT) May 26 21:34 -- 22:36 under mean seeing of about 3 arcsec. No objects is detected in enhanced XRT error circle (Beardmore et al. GCN 10800). The upper limit in a stacked image based on USNO-B1.0 star 1156-0223950 (assuming R=18.44) is following: T0+ Filter, Exposure, mag. (mid, d) (s) 0.2354 R 20x180 > 21.4 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10927 SUBJECT: GRB 100526A: Gemini/NIRI afterglow confirmation and host galaxy DATE: 10/07/02 22:51:48 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley, J. S. Bloom, and S. B. Cenko (UC Berkeley) report: We re-observed the field of GRB 100526A (Vetere et al., GCN 10797) with NIRI on Gemini-North between 08:30 and 09:00 UT on 2010-06-24 UT. We acquired 27 images of 60 seconds each in K-band. Comparison to our previous K-band imaging of this field (Perley et al., GCN 10806) shows the infrared counterpart to have faded significantly. A source is still detected at high significance at the afterglow position. Using the same 2MASS reference star as for our previous epoch, we measure a magnitude of: K = 21.2 +/- 0.2 (t_mid = 27.7 days) This corresponds to a decay index (t^-alpha) of only alpha~0.5 from our previous epoch, which is much slower than expected for a late-time afterglow, and suggests that the current epoch is likely host-galaxy dominated. A comparison image is posted to: http://lyra.berkeley.edu/~dperley/100526a/100526a_niri.png