//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10491 SUBJECT: GRB 100316C: Swift detection of a burst DATE: 10/03/16 09:12:15 GMT FROM: Michael Stamatikos at OSU/GSFC M. Stamatikos (OSU/NASA/GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), S. Campana (INAF-OAB), P. A. Evans (U Leicester), J. M. Gelbord (PSU), C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC), O. M. Littlejohns (U Leicester), R. Margutti (Univ Bicocca&OAB), C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester), C. Pagani (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), M. H. Siegel (PSU), R. L. C. Starling (U Leicester) and L. Vetere (PSU) report on behalf of the Swift Team: At 08:57:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100316C trigger=416115). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 32.291, -68.009 which is RA(J2000) = 02h 09m 10s Dec(J2000) = -68d 00' 31" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 7 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 08:59:17.9 UT, 78.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 32.2869, -67.9914 which is equivalent to: RA(J2000) = 02h 09m 8.85s Dec(J2000) = -67d 59' 29.1" with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 63 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 in excess of the Galactic value (3.94e+20 cm-2, Kalberla et al. 2005), with an excess column of 2.6 (+2.05/-1.79) x 1021 cm-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 81 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 overlap of the 8'x8' region for the list of sources generated on-board and the BAT error circle is uncertain. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 AT 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: 10497 SUBJECT: GRB 100316C: BOOTES-3 observations DATE: 10/03/16 13:30:41 GMT FROM: Martin Jelinek at Inst.Astrophys.Andalucia,Granada M. Jelinek (IAA-CSIC), A. de Ugarte Postigo (INAF-OAB), A.J. Castro-Tirado (IAA-CSIC), J. Gorosabel (IAA-CSIC), P. Kubanek (IPL UV, IAA-CSIC), R. Cunniffe (IAA-CSIC), S. Guziy (IAA-CSIC), P. Yock (Auckland Univ.), W.H. Allen (Vintage Lane Obs.), I. Bond (Massey Univ.), G. Christie (Stardome Obs.), on behalf of a larger collaboration report: "We have observed the field of GRB 100316C (Stamatikos et al., GCN 10491) using the 0.6m Yock-Allen robotic telescope (BOOTES-3) located in Blenheim, New Zealand. Observations began at 8:58:47 UT (49s from GRB onset and 4 s from the GCN alert receipt). We do not detect any source within the XRT error circle in a 20 x 2 second combined unfiltered image down to a 3 sigma limiting magnitude of 18.5." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10506 SUBJECT: GRB 100316C: Enhanced Swift-XRT position DATE: 10/03/16 18:52:07 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 1879 s of XRT Photon Counting mode data and 2 UVOT images for GRB 100316C, 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 = 32.28660, -67.99098 which is equivalent to: RA (J2000): 02h 09m 8.78s Dec (J2000): -67d 59' 27.5" with an uncertainty of 1.8 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: 10507 SUBJECT: GRB 100316C: Swift-XRT team refined analysis DATE: 10/03/16 19:15:43 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift-XRT team: We have analysed 5.7 ks of XRT data for GRB 100316C (Stamatikos et al. GCN Circ. 10491), from 87 s to 13.5 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 10506). The light curve can be modelled with a doubly-broken power-law, with alpha1 = 0.28 (+0.66,-1.18) until T = 258 (+87/-66) s after the trigger, at which point the decay steepens to alpha2 = 2.53 (+1.18, -0.44). At T = 883 (+1857, -271) s, the decay flattens to alpha3 = 0.76 (+0.27, -0.26). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.6 (+0.5, -0.4). The best-fitting absorption column is 1.8 (+1.6, -1.3) x 10^21 cm^-2, in excess of the Galactic value of 3.9 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 5.1 x 10^-11 (6.2 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 0.76, the count rate at T+24 hours will be 0.0013 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.6 x 10^-14 (8.1 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00416115. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10509 SUBJECT: GRB 100316C: Swift-BAT refined analysis DATE: 10/03/16 20:04:22 GMT FROM: Scott Barthelmy at NASA/GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (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 100316C (trigger #416115) (Stamatikos, et al., GCN Circ. 10491). The BAT ground-calculated position is RA, Dec = 32.309, -67.992 deg which is RA(J2000) = 02h 09m 14.2s Dec(J2000) = -67d 59' 30.3" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a roughly symmetric peak starting at ~T-3 sec, peaking at ~T+3 sec, and ending at ~T+12 sec. T90 (15-350 keV) is 9.3 +- 1.7 sec (estimated error including systematics). The time-averaged spectrum from T-3.0 to T+7.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.58 +- 0.26. The fluence in the 15-150 keV band is 1.8 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+2.12 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/416115/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10510 SUBJECT: GRB100316C: Swift/UVOT Upper Limits DATE: 10/03/16 20:05:15 GMT FROM: Patricia Schady at MSSL/Swift S. R. Oates (MSSL-UCL) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100316C 81s after the BAT trigger (Stamatikos et al., GCN Circ. 10491). We do not detect any source at the enhanced Swift XRT position (Evans et al. GCN Circ. 10506). The 3-sigma upper limits for the finding chart exposures (FC) and summed images are: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- white (FC) 81 231 147 > 20.52 white 521 7450 677 > 21.63 u (FC) 239 489 246 > 19.87 u 644 7039 529 > 20.22 v 570 12991 1326 > 20.45 b 495 7245 549 > 20.72 uvw1 620 6834 333 > 20.24 uvm2 595 13530 741 > 20.60 uvw2 546 7656 471 > 20.57 ------------------------------------------------------------- The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_(B-V) = 0.04 mag. All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10516 SUBJECT: GRB 100316C: GROND Detection of a Optical/NIR Afterglow Candidate DATE: 10/03/17 05:41:37 GMT FROM: Adria C. Updike at Clemson U Paulo Afonso (MPE Garching), Adria Updike (Clemson University), Marco Nardini, Robert Filgas, Abdullah Yoldas, and Jochen Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 100316C (Swift trigger 416115; Stamatikos et al. GCN 10491) simultaneously in g'r'i'z' JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 00:45 UT on March 17, 2010, 15.8 hours after the GRB trigger, and are continuing. They were performed at an average seeing of 1" and at an average airmass of 2. We found a DSS uncataloged source at the edge of the 1.8 Swift-XRT error circle reported by Evans et al. (GCN 10506) at RA (J2000.0) = 02 h 09 m 09.11 s DEC (J2000.0) = -67d 59' 26.8" with an uncertainty of 0.5" in each coordinate. Based on the first 31 min of total exposures in g'r'i'z', we estimate preliminary magnitudes (all in AB system) of g' = 23.7 +/- 0.1 mag, r' = 24.4 +/- 0.1 mag, i' > 23.6 mag, z' > 23.9 mag. Further observations are necessary to confirm variability. If this is indeed the afterglow of GRB 100316C, the colors indicate a redshift less than 3.5. Given magnitudes are calibrated against GROND zeropoints and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.03 mag in the direction of the burst (Schlegel et al. 1998). JHK reduction is ongoing.