//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18926 SUBJECT: GRB 160123A: Swift detection of a burst DATE: 16/01/23 09:18:57 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA D. Malesani (DARK/NBI), S. D. Barthelmy (GSFC), T. Sakamoto (AGU) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 08:58:20 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160123A (trigger=671447). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 150.286, -33.779 which is RA(J2000) = 10h 01m 09s Dec(J2000) = -33d 46' 43" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 25 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 08:59:38.1 UT, 78.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 150.3125, -33.7754 which is equivalent to: RA(J2000) = 10h 01m 14.99s Dec(J2000) = -33d 46' 31.3" with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 80 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.31 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 2.9 (+2.66/-2.30) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 250 seconds with the U filter starting 295 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 19.2 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.10. Burst Advocate for this burst is D. Malesani (malesani AT dark-cosmology.dk). 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: 18927 SUBJECT: GRB 160123A: Enhanced Swift-XRT position DATE: 16/01/23 12:14:56 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 1168 s of XRT Photon Counting mode data and 2 UVOT images for GRB 160123A, 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 = 150.31272, -33.77522 which is equivalent to: RA (J2000): 10h 01m 15.05s Dec (J2000): -33d 46' 30.8" 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: 18928 SUBJECT: GRB 160123A: LCOGT-SSO optical upper limit DATE: 16/01/23 16:38:07 GMT FROM: Dong Xu at NAOC/CAS Y.-D. Hu (IAA-CSIC), D. Xu (NAOC/CAS), Y. Qing (Geneva Observatory), Y.-H. Han (NAOC/CAS, HUST) report: We observed the field of GRB 160123A (Malesani et al., GCN 18926) using the LCOGT-1m located at the Siding Spring Observatory. We obtained 20x150s R-band images, starting at 12:04:41 UT on 2016-01-23, i.e., 3.106 hr after the burst. No optical source is detected at the enhanced XRT position of this GRB (Beardmore et al., GCN 18927), down to a limiting magnitude of R~21.0 mag, calibrated with nearby USNO B1 stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18929 SUBJECT: GRB 160123A: Swift-BAT refined analysis DATE: 16/01/23 18:39:27 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. Malesani (DARK/NBI), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 160123A (trigger #671447) (Malesani, et al., GCN Circ. 18926). The BAT ground-calculated position is RA, Dec = 150.277, -33.790 deg, which is RA(J2000) = 10h 01m 06.4s Dec(J2000) = -33d 47' 23.1" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 68%. The mask-weighted light curve shows one peak starting at ~T-15 sec, peaking at ~T+0.5 sec, and ending at ~T+10 sec. T90 (15-350 keV) is 3.95 +- 0.62 sec (estimated error including systematics). The time-averaged spectrum from T-2.05 to T+3.00 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.51 +- 0.16. The fluence in the 15-150 keV band is 3.5 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.01 sec in the 15-150 keV band is 1.3 +- 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/671447/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18930 SUBJECT: GRB 160123A: Swift-XRT refined Analysis DATE: 16/01/23 20:04:33 GMT FROM: Phil Evans at U of Leicester L.M. McCauley (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Maselli (INAF-IASFPA) and D. Malesani report on behalf of the Swift-XRT team: We have analysed 10.0 ks of XRT data for GRB 160123A (Malesani et al. GCN Circ. 18926), from 64 s to 24.2 ks after the BAT trigger. The data comprise 7 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 18927). The light curve can be modelled with a power-law decay with a decay index of alpha=0.72 (+/-0.05). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.09 (+0.28, -0.26). The best-fitting absorption column is 2.6 (+1.2, -1.0) x 10^21 cm^-2, in excess of the Galactic value of 1.3 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.6 (+1.2, -1.0) x 10^21 cm^-2 Galactic foreground: 1.3 x 10^21 cm^-2 Excess significance: 2.2 sigma Photon index: 2.09 (+0.28, -0.26) If the light curve continues to decay with a power-law decay index of 0.72, the count rate at T+24 hours will be 3.6 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-13 (1.9 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/00671447. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18931 SUBJECT: GRB 160123A: Swift/UVOT Upper Limits DATE: 16/01/23 21:44:10 GMT FROM: Massimiliano de Pasquale at IASF-Palermo M. De Pasquale (UCL-MSSL) and D. Malesani (DARK/NBI) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160123A 82 s after the BAT trigger (Malesani et al., GCN Circ. 18926). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 18927) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 82 231 147 >20.7 u_FC 296 545 246 >19.9 white 82 1196 1041 >21.8 v 626 11136 1191 >20.3 b 551 17792 1337 >21.4 u 296 17792 1563 >20.4 w1 675 12760 1152 >19.2 m2 650 12040 1160 >20.0 w2 601 6977 471 >21.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.10 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18932 SUBJECT: GRB 160123A: NOT J-band observations DATE: 16/01/24 02:59:39 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst Daniele Malesani (DARK/NBI), Anlaug Amanda Djupvik (NOT), Tom Reynolds (NOT and Tuorla Obs.), and Pall Jakobsson (Univ. Iceland) report on behalf of a larger collaboration: We observed the field of GRB 160123A (Malesani et al., GCN 18926) with the Nordic Optical Telescope (NOT) equipped with the NOTCam near-infrared camera. Observations were carried out in the J filter. Sky conditions were not optimal, with moonlit clouds and a seeing of 1.7". Three sets of nine images by 1 minute each were acquired, starting on Jan 24.067 UT (16.6 hr after the GRB). After stacking the best 18 images, no source is detected within the XRT localization area (Beardmore et al., GCN 18927; see also http://www.swift.ac.uk/xrt_positions/00671447/), down to a limiting magnitude J > 19.5 (Vega), calibrated against the 2MASS catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18936 SUBJECT: GRB 160123A: GROND Upper limits DATE: 16/01/26 12:50:15 GMT FROM: John Graham at MPE/Garching J. F. Graham, T. Schweyer, and J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 160123A (Swift trigger 671447; Malesani, et al., GCN # 18926) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 04:02 UT on 25 Jan 2016, approximately 43 hours after the GRB trigger, and lasted for 2 hours. They were performed at an average seeing of 1.64" and at an average airmass of 1.06. We do not detect a source within the Swift-XRT error circle reported by Beardmore et al. (GCN # 18927) down to (AB magnitudes) g' > 24.1 mag, r' > 24.4 mag, i' > 24.0 mag, z' > 23.9 mag, J > 21.3 mag, H > 20.9 mag, and K > 20.1 mag. The given limits are derived based on calibrating the images against GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.10 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18942 SUBJECT: GRB 160123A: TAROT La Silla observatory optical observations DATE: 16/01/27 15:38:47 GMT FROM: Alain Klotz at IRAP-CNRS-OMP Klotz A., Turpin D. (IRAP-CNRS-OMP), Boer M., Gendre B., Bardho O. (UNS-CNRS-OCA), Gendre B. (Etelman Observatory-UVI), Atteia J.L. (IRAP-CNRS-OMP) report: We imaged the field of GRB 160123A detected by SWIFT (trigger 671447) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile. The observations started 33.1s after the GRB trigger (14.2s after the notice). The elevation of the field decreased from 59 degrees above horizon and weather conditions were good. The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect any OT with a limiting magnitude of: t0+33.1s to t0+93.1s : R > 17.3 The second image is 30.0s exposure in tracking mode: t0+108.7s to t0+138.7s : R > 18.1 We co-added a series of exposures: t0+108.7s to t0+305.4s : R > 18.8 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.