//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15029 SUBJECT: GRB 130725B: Swift detection of a burst DATE: 13/07/25 18:06:07 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT C. A. Swenson (PSU), M. M. Chester (PSU), D. Grupe (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU) and B.-B. Zhang (UAH) report on behalf of the Swift Team: At 17:39:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130725B (trigger=564028). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 214.232, -11.140 which is RA(J2000) = 14h 16m 56s Dec(J2000) = -11d 08' 24" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). BAT light curve data are currently unavailable. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 214.24096, -11.12909 which is equivalent to: RA(J2000) = 14h 16m 57.83s Dec(J2000) = -11d 07' 44.7" with an uncertainty of 4.4 arcseconds (radius, 90% containment). 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 (5.15 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 3.4 (+4.04/-3.23) x 10^21 cm^-2 (90% confidence). UVOT data are unavailable at this time. Burst Advocate for this burst is C. A. Swenson (cswenson 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: 15032 SUBJECT: GRB 130725B: Swift/UVOT Detection of an Optical Counterpart DATE: 13/07/25 21:56:37 GMT FROM: Mike Siegel at PSU/Swift MOC M. H Siegel and C. A. Swenson (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130725B 72 s after the BAT trigger (Swenson et al., GCN Circ. 15029). A source consistent with the XRT position (Swenson et al. GCN Circ. 15029) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 14:16:57.76 = 214.24068 (deg.) Dec (J2000) = -11:07:41.8 = -11.12827 (deg.) with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence). Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 72 221 147 17.29 +/- 0.03 u 284 534 246 17.96 +/- 0.07 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.061 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15034 SUBJECT: GRB 130725B: GROND Detection of the Optical/NIR Afterglow DATE: 13/07/26 05:30:18 GMT FROM: Felipe Olivares Estay at MPE M. Tanga (MPE Garching), F. Olivares E. (UNAB, MCSS), and J. Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 130725B (Swift trigger 564028; Swenson et al., GCN #15029) simultaneously in g'r'i'z'JHK 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 00:47 UT on July 26, 2013, 7.1 hours after the GRB trigger. They were performed at an average seeing of 1.5" and at an average airmass of 1.2. We detect the afterglow at the position of Siegel et al. (GCN #15032), and based on the first images with total exposures of 4.4 minutes in g'r'i'z' and 8 minutes in JHK, we estimate preliminary magnitudes (all in AB) of g' = 21.1 +/- 0.1 mag, r' = 20.5 +/- 0.1 mag, i' = 20.4 +/- 0.1 mag, z' = 20.4 +/- 0.1 mag, J = 20.4 +/- 0.3 mag, H = 19.9 +/- 0.3 mag, and K = 19.5 +/- 0.4 mag. Given magnitudes are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E(B-V) = 0.061 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15038 SUBJECT: GRB 130725B - UVOT-enhanced XRT position DATE: 13/07/26 13:28:49 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA B. Sbarufatti (INAF-OAB/PSU), C. Swenson (PSU), P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team: Using 4385 s of XRT Photon Counting mode data and 5 UVOT images, 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 = 214.24065, -11.12845 which is equivalent to: RA (J2000): 14 16 57.76 Dec (J2000): -11 07 42.4 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). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15039 SUBJECT: GRB130725B: REM-ROS2 optical observations DATE: 13/07/26 13:48:28 GMT FROM: Dino Fugazza at INAF-OAB D. Fugazza, S. Covino, G. Tagliaferri (INAF-OAB), V. D'Elia (INAF-OAR) report on behalf of the CIBO team: We observed the field of GRB 130725B (Swenson et al., GCN 15029) simultaneously in the optical and near-infrared with the the 60-cm robotic telescope REM at La Silla Observatory (Chile). The observations started at 23:41:40 UT on July 25 2013, about 6.03 hours after the GRB and lasted for about 45 min. We detect the afterglow reported by Siegel et al. (GCN 15032) and Tanga et al. (GCN 15034) with the upgraded ROS2 optical camera. In the NIR with REMIR camera the afterglow was not detected. ROS2 is able to observe simultaneously in the g', r', i', and z' filters and preliminary magnitudes (AB) are: g' = 20.65 ± 0.07 r' = 20.32 ± 0.07 i' = 20.08 ± 0.09 The magnitudes are calibrated against the APASS catalogue. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15040 SUBJECT: GRB 130725B: Swift-XRT refined Analysis DATE: 13/07/26 15:10:08 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA B. Sbarufatti (INAF-OAB/PSU) and C. A. Swenson (PSU) report on behalf of the Swift-XRT team: We have analysed 8.2 ks of XRT data for GRB 130725B (Swenson et al. GCN Circ. 15029), from 53 s to 35.0 ks after the BAT trigger. The data comprise 235 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. Using 6414 s of PC mode data and 9 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 214.24059, -11.12851 which is equivalent to: RA (J2000): 14h 16m 57.74s Dec(J2000): -11d 07' 42.6" with an uncertainty of 1.4 arcsec (radius, 90% confidence). The light curve can be modelled with an initial power-law decay with an index of alpha=0.09 (+0.15, -0.18), followed by a break at T+534 s to an alpha of 0.95 (+/-0.05). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.97 (+0.17, -0.16). The best-fitting absorption column is 8.3 (+4.2, -3.2) x 10^20 cm^-2, consistent with the Galactic value of 5.2 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 3.6 x 10^-11 (4.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 8.3 (+4.2, -3.2) x 10^20 cm^-2 Galactic foreground: 5.2 x 10^20 cm^-2 Photon index: 1.97 (+0.17, -0.16) If the light curve continues to decay with a power-law decay index of 0.95, the count rate at T+24 hours will be 0.012 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.5 x 10^-13 (5.5 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/00564028. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15041 SUBJECT: GRB 130725B, Swift-BAT refined analysis DATE: 13/07/26 15:24:07 GMT FROM: Hans Krimm at NASA-GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), C. A. Swenson (PSU), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+454 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130725B (trigger #564028) (Swenson, et al., GCN Circ. 15029). The BAT ground-calculated position is RA, Dec = 214.233, -11.124 deg which is RA(J2000) = 14h 16m 55.9s Dec(J2000) = -11d 07' 26.3" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The mask-weighted light curve shows a single FRED burst peaking at T+1 sec and decaying to baseline by about T+8 sec. T90 (15-350 keV) is 10.0 +- 3.6 sec (estimated error including systematics). The time-averaged spectrum from T-0.3 to T+12.8 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.23 +- 0.17. The fluence in the 15-150 keV band is 3.9 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.29 sec in the 15-150 keV band is 2.2 +- 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/564028/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15044 SUBJECT: GRB 130725B: Swift trigger time correction DATE: 13/07/26 17:26:01 GMT FROM: Craig Swenson at PSU/Swift C. A. Swenson (PSU) reports on behalf of the Swift team: The BAT trigger time for GRB 130725B (GCN Circ. 15029) was incorrectly identified. The correct trigger time is 17:39:28 UT. We apologize for any inconvenience. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15045 SUBJECT: GRB 130725B: Swift/UVOT Observations DATE: 13/07/26 17:50:43 GMT FROM: Frank Marshall at GSFC S. R. Oates (UCL-MSSL) and C. A. Swenson (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130725B 72 s after the BAT trigger (Swenson et al. GCN Circ. 15029; Swenson GCN Circ. 15044). A source consistent with the enhanced XRT position (Sbarufatti and Swenson GCN Circ. 15040) is detected in the initial UVOT exposures in all filters except for uvm2 and uvw2. The non-detection in these filters suggests a redshift ~<2. The preliminary UVOT position is: RA (J2000) = 14:16:57.76 = 214.24068 (deg.) Dec (J2000) = -11:07:41.8 = -11.12827 (deg.) with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 72 221 147 16.67 +/- 0.03 v 614 6315 252 19.16 +/- 0.27 b 540 559 19 18.20 +/- 0.28 u 284 534 246 17.35 +/- 0.06 w1 663 6725 236 20.01 +/- 0.36 m2 6320 16621 1003 >21.1 w2 4265 4465 197 >20.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.061 in the direction of the burst (Schlegel et al. 1998).