//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10317 SUBJECT: GRB 100111A: Swift detection of a burst with an optical afterglow DATE: 10/01/11 04:24:29 GMT FROM: David Palmer at LANL L. Vetere (PSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), C. Gronwall (PSU), D. Grupe (PSU), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), C. B. Markwardt (CRESST/GSFC/UMD), C. Pagani (PSU), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 04:12:49 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100111A (trigger=382399). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 247.038, +15.557 which is RA(J2000) = 16h 28m 09s Dec(J2000) = +15d 33' 25" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a small precursor peak followed by a main FRED peak for a total duration of about 30 sec. The peak count rate was ~3800 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 04:13:52.1 UT, 63.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 247.04766, 15.55090 which is equivalent to: RA(J2000) = 16h 28m 11.44s Dec(J2000) = +15d 33' 03.2" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 40 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 (4.09e+20 cm^-2, Kalberla et al. 2005), with an excess column of 2 (+2.19/-1.28) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 67 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 16:28:11.60 = 247.04833 DEC(J2000) = +15:33:02.3 = 15.55064 with a 90%-confidence error radius of about 0.62 arc sec. This position is 3.4 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.58 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.05. 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: 10318 SUBJECT: GRB 100111A: NOT optical observations DATE: 10/01/11 09:43:35 GMT FROM: Johan U. Fynbo at U.Copenhagen D. Xu (WIS, DARK/NBI), N. Tanvir (U. Leicester), J.P.U. Fynbo (DARK/NBI), P. Jakobsson (Univ. of Iceland), T. Liimets (NOT) report on behalf of a larger collaboration: We observed the field of GRB100111A (Vetere et al., GCN 10317) with the Nordic Optical Telescope equipped with ALFOSC. A 30 s R-band frame was obtained, starting at 05:25:45 UT on Jan 11, 73 min after the burst trigger. The afterglow is clearly detected in the frame with R=19.46+/-0.05 mag calibrated with the nearby #1055-0262005 star in the USNO B1 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10319 SUBJECT: GRB 100111A: Fermi GBM observation DATE: 10/01/11 16:24:31 GMT FROM: Sheila McBreen at MPE S. McBreen (UCD/MPE) reports on behalf of the Fermi GBM Team: "At 04:12:49.70 UT on 11 January 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100111A (trigger 284875971 / 100111176) which was also detected by the Swift-BAT (Vetere et al. 2010, GCN 10317). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 32 degrees. The GBM light curve consists of one main pulse with a duration of about 12 s (8-1000 keV). The time-averaged spectrum from T0-2.7 s to T0+5.5 s is adequately fit by a simple power law function with index -1.66 (+0.05/-0.06) (CSTAT 452 for 363 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.5 +/- 0.1 )E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.003 s in the 8-1000 keV band is 3.5 +/- 0.3 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: 10320 SUBJECT: GRB100111A: Swift-XRT refined analysis DATE: 10/01/11 16:53:52 GMT FROM: Loredana Vetere at PSU L. Vetere (PSU) reports on behalf of the Swift-XRT team: We have analysed 774 s of XRT data for GRB 100111A (Vetere et al. GCN Circ. 10317), from 77 s to 852 s after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=0.58 +/- 0.16. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.10 (+0.29, -0.26). The best-fitting absorption column is 1.7 (+0.8, -0.7) x 10^21 cm^-2, in excess of the Galactic value of 4.1 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 3.8 x 10^-11 (5.7 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 0.58, the count rate at T+24 hours will be 0.023 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.7 x 10^-13 (1.3 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00382399. This circular is an official product of the Swift-XRT team.//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10321 SUBJECT: GRB 100111A: Enhanced Swift-XRT position DATE: 10/01/11 17:24:58 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 5361 s of XRT Photon Counting mode data and 10 UVOT images for GRB 100111A, 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 = 247.04845, +15.55083 which is equivalent to: RA (J2000): 16h 28m 11.63s Dec (J2000): +15d 33' 03.0" 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). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10322 SUBJECT: GRB 100111A: Swift-BAT refined analysis DATE: 10/01/11 20:16:16 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/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+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100111A (trigger #382399) (Vetere, et al., GCN Circ. 10317). The BAT ground-calculated position is RA, Dec = 247.029, 15.539 deg which is RA(J2000) = 16h 28m 06.9s Dec(J2000) = +15d 32' 19.1" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a weak peak at ~T-30 sec and the main FRED-like peak from ~T-10 sec and ending at ~T+25 sec. T90 (15-350 keV) is 12.9 +- 2.1 sec (estimated error including systematics). The time-averaged spectrum from T-7.5 to T+8.7 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.69 +- 0.13. The fluence in the 15-150 keV band is 6.7 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.03 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/382399/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10323 SUBJECT: GRB 100111A: Swift UVOT Refined Analysis DATE: 10/01/11 21:17:29 GMT FROM: Erik Hoversten at Swift/Penn State E. A. Hoversten (PSU) and L. Vetere (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100111A 67 s after the BAT trigger (Vetere, et al., GCN Circ. 10317). A source is detected at 17.62 magnitudes in the initial white finding chart at the position RA, Dec (J2000) = 247.04833, 15.55064 which is equivalent to: RA(J2000) = 16:28:11.60 = 247.04833 DEC(J2000) = +15:33:02.3 = 15.55064 with a 90%-confidence error radius of about 0.51 arc sec. This position is 0.8 arcsec from the UVOT-enhanced XRT position (Beardmore, et al. GCN Circ. 10321) and the two positions agree within the error bars. The source faded by more than a magnitude in the white filter over the first orbit of observations. Additionally the source is detected in the b, u, and uvw1 filters, with a marginal 2.4-sigma detection in v and a 2.1-sigma detection in uvm2. Given the detection in the uvw1 filter the redshift of this burst is less than 1.9. The observed magnitudes and 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the initial exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag ============================================================= white 67 217 147 17.62 +/- 0.05 white 858 1007 147 18.73 +/- 0.10 v 609 1057 58 > 18.41 b 535 727 39 18.76 +/- 0.27 u 279 529 245 17.37 +/- 0.07 uvw1 658 851 38 18.57 +/- 0.36 uvm2 633 827 38 > 18.99 uvw2 584 1033 58 > 19.04 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10324 SUBJECT: GRB 100111A: PAIRITEL NIR Upper Limits DATE: 10/01/11 22:35:56 GMT FROM: Adam Morgan at U.C. Berkeley A. N. Morgan, S. B. Cenko, J. S. Bloom, (UC Berkeley), report: We observed the field of GRB 100111A (Vetere et al., GCN 10317) with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2010-01-11 12:20:11 UT, ~8.12 hours after the Swift trigger. Observations were taken under good weather conditions but at high airmass before dawn. In mosaics (effective exposure time of ~2223 seconds) taken simultaneously in the J, H, and Ks filters, we do not detect the optical afterglow (Vetere et al., GCN 10317; Xu et al., GCN 10318; Hoversten et al., GCN 10323). The preliminary photometry yields: post_burst t_mid(h) exp(s) filt U. Limit (3 sig) 8.60 2223 J > 19.0 8.60 2223 H > 18.5 8.60 2223 Ks > 18.0 All magnitudes given in the Vega system, calibrated to 2MASS. No correction for Galactic extinction has been made to the above reported values. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10822 SUBJECT: GRB 100111A: Maidanak optical observations DATE: 10/06/01 20:34:43 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (SAI MSU), M. Ibrahimov, R. Karimov (MAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow of the Swift GRB 100111A (Vetere et al. GCN 10317) with AZT-22 (1.5 m) telescope of Maidanak observatory (MAO) in R band on Jan. 12 (UT) (00:44 - 01:32) under good weather conditions with mean seeing of about 0.8 arcsec. The optical afterglow (Vetere et al. GCN 10317) is clearly detected in enhanced XRT error circle (Beardmore et al. GCN 10321). A photometry of combined image is based on several SDSS DR7 field stars: T0+ Filter Exp. Mag. UL mid., days seconds (3 sigma) 0.8687 R 8*300 22.92 +/- 0.18 23.56 Comparing with R-magnitude reported by Xu et al. (GCN 10318) (R=19.46+/-0.05 in 0.05 days) one can obtain power-law decay index of about 1.12.