//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12450 SUBJECT: GRB 111018A: Swift detection of a burst DATE: 11/10/18 17:43:51 GMT FROM: Scott Barthelmy at NASA/GSFC F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), M. M. Chester (PSU), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), V. Mangano (INAF-IASFPA), D. M. Palmer (LANL), M. H. Siegel (PSU), R. L. C. Starling (U Leicester), C. A. Swenson (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/ORAU) and B.-B. Zhang (PSU) report on behalf of the Swift Team: At 17:26:24 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 111018A (trigger=505801). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 271.500, -3.871 which is RA(J2000) = 18h 06m 00s Dec(J2000) = -03d 52' 16" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows two weak peaks at T+0 and T+30 sec with a total duration of about 40 sec. The peak count rate was ~500 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 17:28:27.6 UT, 123.0 seconds after the BAT trigger. The position determined from promptly downlinked data differs significantly from the on-board position, suggesting that the XRT may have centroided on a cosmic ray; the initial XRT position notice should be treated with caution. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 271.48887, -3.90719 which is equivalent to: RA(J2000) = 18h 05m 57.33s Dec(J2000) = -03d 54' 25.9" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 135 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 consistent with the Galactic value of 2.54 x 10^21 cm^-2 (Kalberla et al. 2005). UVOT took a finding chart exposure of 150 seconds with the White filter starting 132 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 2.16. Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.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: 12453 SUBJECT: GRB 111018A: Enhanced Swift-XRT position DATE: 11/10/19 00:01:32 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1590 s of XRT Photon Counting mode data and 2 UVOT images for GRB 111018A, 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 = 271.48854, -3.90728 which is equivalent to: RA (J2000): 18h 05m 57.25s Dec (J2000): -03d 54' 26.2" with an uncertainty of 2.0 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: 12454 SUBJECT: GRB 111018A: GROND Upper Limits DATE: 11/10/19 06:21:50 GMT FROM: Jochen Greiner at MPI M. Nardini (Uni. Milano-Bicocca), J. Elliott and J. Greiner (both MPE Garching) report on behalf of the GROND team: We observed the field of GRB111018A (Swift trigger 505801; Marhsal et al., GCN #12450) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory (Chile). Observations started at 23:47 UT on 18 October 2011, 6.35 hours after the trigger. They were performed at an average seeing of 2.8 and at an average airmass of 1.9. Based on images with total exposures of 1500 s in g'r'i'z' and 1200 s in JHK, we do not detect a source within the Swift-XRT error circle reported by Goad et al. (GCN #12453) down to (all AB): g' > 23.2, r' > 23.5, i' > 22.5, z' > 22.2, J > 20.0, H > 18.9, K > 18.6 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 the heavy reddening of E(B-V)=2.16 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12455 SUBJECT: GRB 111018A: Swift-XRT refined Analysis DATE: 11/10/19 07:53:17 GMT FROM: Vanessa Mangano at INAF-IASFPA V. Mangano (INAF IASFPA) and F. E. Marshall (NASA/GSFC) reports on behalf of the Swift-XRT team: We have analysed 11 ks of XRT data for GRB 111018A (Marshall et al. GCN Circ. 12450), from 115 s to 36.2 ks after the BAT trigger. The data comprise 37 s in Windowed Timing (WT) mode (the first 6 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN. Circ 12453). The light curve can be modelled with a power-law decay with a decay index of alpha=1.01 (+0.15, -0.13). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.8 (+0.8, -0.7). The best-fitting absorption column is 1.2 (+0.8, -0.6) x 10^22 cm^-2, in excess of the Galactic value of 2.5 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.7 x 10^-11 (1.2 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.2 (+0.8, -0.6) x 10^22 cm^-2 Galactic foreground: 2.5 x 10^21 cm^-2 Excess significance: 3.4 sigma Photon index: 1.8 (+0.8, -0.7) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00505801. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12457 SUBJECT: GRB 111018A: Swift-BAT refined analysis DATE: 11/10/19 11:49:22 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 111018A (trigger #505801) (Marshall, et al., GCN Circ. 12450). The BAT ground-calculated position is RA, Dec = 271.482, -3.880 deg, which is RA(J2000) = 18h 05m 55.6s Dec(J2000) = -03d 52' 48.5" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 80%. The mask-weighted light curve shows a couple overlapping peaks starting at ~T-4 sec, peaking at ~T-1 and ~T+22 sec, and ending at ~T+35 sec, possibly out to T+75 sec. T90 (15-350 keV) is 36 +- 5 sec (estimated error including systematics). The time-averaged spectrum from T-4.08 to T+37.30 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.18 +- 0.27. The fluence in the 15-150 keV band is 4.0 +- 0.7 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+21.71 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/505801/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12459 SUBJECT: GRB 111018A: Swift/UVOT Upper Limits DATE: 11/10/19 12:59:31 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (MSSL-UCL) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 111018A 132 s after the BAT trigger (Marshall et al., GCN Circ. 12450). No optical afterglow consistent with the refined XRT position (Goad et al., GCN Circ. 12453) 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 132 282 147 >21.1 white 132 7508 653 >21.8 v 462 12028 673 >20.2 b 388 6000 333 >20.9 u 291 5794 329 >20.6 uvw1 512 5590 314 >20.4 uvm2 487 5384 333 >20.2 uvw2 438 11672 1040 >21.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 2.16 in the direction of the burst (Schlegel et al. 1998).