//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12394 SUBJECT: GRB 110928A: Swift detection of a burst DATE: 11/09/28 02:03:46 GMT FROM: Scott Barthelmy at NASA/GSFC E. A. Hoversten (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), H. A. Krimm (CRESST/GSFC/USRA), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and E. Sonbas (GSFC/USRA/Adiyaman Univ.) report on behalf of the Swift Team: At 01:51:31 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110928A (trigger=504215). Swift will slew after 52 minutes after the Earth limb constraint is avoided. The BAT on-board calculated location is RA, Dec 257.755, +36.570, which is RA(J2000) = 17h 11m 01s Dec(J2000) = +36d 34' 13" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single FRED-like pulse with a duration of about 10 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+52 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is E. A. Hoversten (hoversten 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: 12395 SUBJECT: GRB 110928A: ROTSE-III Optical Limits DATE: 11/09/28 02:32:52 GMT FROM: Brad Schaefer at LSU B. E. Schaefer (Louisiana State), W. Zheng (U Mich), H. Flewelling (IfA/Hawaii), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 110928A (Swift trigger 504215; Hoversten et al., GCN 12394), producing images beginning 7.1 s after the GCN notice time. An automated response took the first image at 01:52:39.1 UT, 67.3 s after the burst, under excellent conditions. We took 10 5-sec, 10 20-sec and 10 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going. Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle, for both single images and coadding into sets of 10; the field is not crowded. Individual images have limiting magnitudes ranging from 16.1-17.4; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:52:39.1 01:52:44.1 5 16.1 67.3 N 01:52:39.1 01:54:26.8 107 17.5 67.3 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12396 SUBJECT: GRB 110928A: PAIRITEL NIR Observations DATE: 11/09/28 02:37:03 GMT FROM: Adam Morgan at U.C. Berkeley C. R. Klein and A. N. Morgan (U. C. Berkeley) report: We observed the field of GRBs 110928A (Hoverston et al., GCN 12394) with the 1.3m PAIRITEL located at Mt. Hopkins, AZ. Observations began at 2011-Sep-28 02h03m59s, 12.5 minutes after the GRB. In mosaics (effective exposure time of 468s) taken simultaneously in the J, H, and Ks filters, we do not clearly detect any new sources in the BAT error circle down to the limit of the 2mass catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12397 SUBJECT: GRB 110928A: Swift/UVOT finding chart observation DATE: 11/09/28 03:09:54 GMT FROM: Erik Hoversten at Swift/Penn State E. A. Hoversten (PSU) reports on behalf of the Swift UVOT team: UVOT took a finding chart exposure of 150 seconds with the white filter of the field of GRB 110928A starting 3341 seconds after the BAT trigger (Hoversten et al., GCN 12394). No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. 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 0.03. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12398 SUBJECT: GRB 110928A: Swift-XRT observations DATE: 11/09/28 03:51:12 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), S. Campana (INAF-OAB) and G. Cusumano (INAF-IASF PA) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 110928A at 02:47:09.1 UT, 3337.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 257.73360, 36.53636 which is equivalent to: RA(J2000) = 17h 10m 56.06s Dec(J2000) = +36d 32' 10.9" with an uncertainty of 4.3 arcseconds (radius, 90% containment). This location is 136 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 (3.14 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.1 (+2.44/-1.70) x 10^22 cm^-2 (90% confidence). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12399 SUBJECT: GRB 110928A: Swift-BAT refined analysis DATE: 11/09/28 04:17:24 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), E. A. Hoversten (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 110928A (trigger #504215) (Hoversten, et al., GCN Circ. 12394). The BAT ground-calculated position is RA, Dec = 257.745, 36.547 deg, which is RA(J2000) = 17h 10m 58.7s Dec(J2000) = +36d 32' 49.3" with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 37%. The mask-weighted light curve shows a single FRED-like peak starting at ~T_zero and ending at ~T+30 sec. T90 (15-350 keV) is 26.7 +- 4.8 sec (estimated error including systematics). The time-averaged spectrum from T-0.53 to T+27.88 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.09 +- 0.30. The fluence in the 15-150 keV band is 6.9 +- 1.1 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+6.84 sec in the 15-150 keV band is 0.9 +- 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/504215/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12400 SUBJECT: GRB 110928A: Further PAIRITEL NIR Observations DATE: 11/09/28 04:28:47 GMT FROM: Adam Morgan at U.C. Berkeley A. N. Morgan, C. R. Klein and J. S. Bloom (UC Berkeley) report: We observed the field of GRB 110928A (Hoversten et al., GCN 12394) with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2011-Sep-28 02h03m59s UT, ~12.5 min after the Swift trigger. In mosaics (effective exposure time of 678.6 s) taken simultaneously in the J, H, and Ks filters, we do not detect any source within the XRT error circle (Evans et al. GCN 12398). post burst t_mid (hr) exp.(hr) filt U. Limit (3 sig) 0.36 0.19 J > 18.2 0.36 0.19 H > 17.5 0.36 0.19 Ks > 15.9 Deeper NIR observations are underway. All magnitudes are 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: 12401 SUBJECT: GRB 110928A: P60 Observations DATE: 11/09/28 05:59:37 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko (UC Berkeley) reports on behalf of a larger collaboration: We have imaged the field of GRB 110928A (Hoversten et al., GCN 12394) with the automated Palomar 60 inch telescope. Observations were obtained in the Sloan r', i', and z' filters beginning at 4:11 UT on 2011 September 28 (~ 2.3 hours after the Swift trigger). We do not detect any sources within the XRT error circle (Evans et al., GCN 12398). Using nearby point sources from the Sloan Digital Sky Survey for reference, we calculate the following upper limits (AB): r' > 22.1 i' > 21.6 z' > 20.3 We note the presence on the northern edge of the XRT error circle of one (possibly two) extended sources present in SDSS. The large size of the current X-ray localization precludes any firm association with GRB 110928A, however. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12402 SUBJECT: GRB 110928A: Enhanced Swift-XRT position DATE: 11/09/28 06:01:13 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 1477 s of XRT Photon Counting mode data and 3 UVOT images for GRB 110928A, 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 = 257.73295, +36.53571 which is equivalent to: RA (J2000): 17h 10m 55.91s Dec (J2000): +36d 32' 08.5" with an uncertainty of 2.2 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: 12404 SUBJECT: GRB 110928A: Swift-XRT refined Analysis DATE: 11/09/28 18:02:01 GMT FROM: Chris Wolf at PSU C. A. Wolf (PSU), E. A. Hoversten (PSU), and K. L. Page (U Leicester) report on behalf of the Swift-XRT team: We have analysed 12 ks of XRT data for GRB 110928A (Hoversten et al. GCN Circ. 12394), from 3.3 ks to 44.3 ks after the BAT trigger. The data was collected in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN. Circ 12402). The light curve can be modelled with a power-law decay with a decay index of alpha=0.55 (+0.17, -0.19). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.07 (+0.34, -0.27). The best-fitting absorption column is 4.8 (+2.5, -1.7) x 10^21 cm^-2, in excess of the Galactic value of 3.1 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 4.4 x 10^-11 (8.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.8 (+2.5, -1.7) x 10^21 cm^-2 Galactic foreground: 3.1 x 10^20 cm^-2 Excess significance: 4.7 sigma Photon index: 2.07 (+0.34, -0.27) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00504215. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12406 SUBJECT: GRB 110928A: Swift/UVOT Upper Limits DATE: 11/09/28 20:38:28 GMT FROM: Erik Hoversten at Swift/Penn State E. A. Hoversten (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110928A 3342 s after the BAT trigger (Hoversten et al., GCN Circ. 12394). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 12402) 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 3342 3492 147 >20.2 white 3342 4723 344 >21.0 v 3499 3698 197 >19.1 b 4319 4518 197 >21.0 u 4114 4313 197 >20.8 w1 3909 4108 197 >20.3 m2 3704 3903 197 >19.9 w2 4729 4929 197 >21.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12407 SUBJECT: GRB 110928A: RAPTOR Limits During Gamma-ray Emitting Interval DATE: 11/09/28 21:11:25 GMT FROM: James Wren at LANL J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis, of Los Alamos National Laboratory report: The RAPTOR network of robotic optical telescopes made observations of Swift trigger 504215 (Hoversten et al., GCN 12394). The burst location was within the field of our wide-field monitors which began a 10 s integration of the location at 01:51:33.0 UT, 1.2 s after the Swift trigger time and during the gamma-ray emitting interval. The next wide-field 10 s integration begins at 01:51:52.1 UT, and is also within the gamma-ray emitting interval. Neither image shows a counterpart at the Swift XRT location (Evans et al., GCN 12398) to an unfiltered 3-sigma limiting magnitude of 10.1 based on comparison to the Tycho-2 V-band. Our narrow-field instruments began imaging at 01:52:40.2 UT, 68.4 s after the Swift trigger. The initial 5 s exposures show no counterpart to a 3-sigma limiting magnitude of 16.1 when compared to the USNO-B1 R-band. The following table gives a sample of our observations. The start time is given as the seconds between the start of the exposure and the initial Swift trigger time. start(s) exp(s) mag limit ------------------------------ 1.22 10.0 > 10.1 20.32 10.0 > 10.1 68.44 5.0 > 16.1 153.55 10.0 > 16.5 413.45 30.0 > 17.2 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12408 SUBJECT: Skynet observations of GRB 110928A DATE: 11/09/29 04:14:54 GMT FROM: Aaron LaCluyze at U.North Carolina J. Haislip, K. Ivarsen, A. LaCluyze, K. McLin, D. Reichart, J. Moore, T. Cromartie, R. Egger, A. Foster, M. Nysewander, A. Oza, E. Speckhard, A. Trotter, and J. A. Crain report: Skynet observed the field of GRB 110928A (Hoverston et al., GCN 12394) with the GLAST Optical Robotic Telescope (GORT) at the Hume observatory in California beginning roughly 75 minutes after the burst. We do not detect any uncatalogued sources. Stacking only images that increase the limiting magnitude yields: mean mean time time 3-sigma since since limiting trigger trigger (days) telescope exposures filter mag 3.186 h 0.13277 GORT 19 x 80 s Ic 20.0 3.400 h 0.14166 GORT 23 x 80 s Rc 21.0 This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12409 SUBJECT: Skynet/Dolomiti observations of GRB 110928A DATE: 11/09/30 04:19:07 GMT FROM: Aaron LaCluyze at U.North Carolina J. Haislip, K. Ivarsen, A. LaCluyze, M. Maturi, D. Reichart, J. Moore, T. Cromartie, R. Egger, A. Foster, N. Frank, M. Nysewander, A. Oza, E. Speckhard, A.Trotter, and J. A. Crain report: Skynet observed the field of GRB 110928A (Hoverston et al., GCN 12394) with the 16" Dolomites Astronomical Observatory telescope (DAO) in Italy beginning roughly 16.3 hours after the burst. We do not detect any uncatalogued sources. Stacking only images that increase the limiting magnitude yields: Mean Time 3-sigma limiting Since trigger Tel Exposures Filter magnitude 17.244 h DAO 37 x 160 s g' 21.0 (0.71850 days) This message may be cited.