//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22828 SUBJECT: GRB 180623A: Swift detection of a burst DATE: 18/06/23 17:00:40 GMT FROM: Scott Barthelmy at NASA/GSFC K. L. Page (U Leicester), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), A. Deich (PSU), S. W. K Emery (UCL-MSSL), J.D. Gropp (PSU), F. E. Marshall (NASA/GSFC) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 16:41:56 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180623A (trigger=844015). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 214.511, -60.294, which is RA(J2000) = 14h 18m 03s Dec(J2000) = -60d 17' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows 4 large peaks and many little peaks with a total duration of about 90 sec. The peak count rate was ~6500 counts/sec (15-350 keV), at ~61 sec after the trigger. The XRT began observing the field at 16:43:13.3 UT, 76.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source with an enhanced position: RA, Dec 214.5295, -60.2539 which is equivalent to: RA(J2000) = 14h 18m 07.08s Dec(J2000) = -60d 15' 13.9" with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 148 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 does not constrain the column density. The initial flux in the 2.5 s image was 1.31e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of nominal 150.000 seconds with the White filter starting 85 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 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain, extinction expected. Although this source is close to the Galactic plane (lat = 0.83 degrees), its distance from the Galactic center (46 degrees), the presence of significant flux above 100 keV, and the complexity and overall shape of the lightcurve are consistent with a GRB that is aligned with the plane due to random coincidence. Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 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: 22829 SUBJECT: GRB 180623A: Enhanced Swift-XRT position DATE: 18/06/23 21:24:42 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 3088 s of XRT Photon Counting mode data and 6 UVOT images for GRB 180623A, 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 = 214.52879, -60.25352 which is equivalent to: RA (J2000): 14h 18m 6.91s Dec (J2000): -60d 15' 12.7" with an uncertainty of 1.5 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: 22830 SUBJECT: GRB 180623A: Swift-XRT refined Analysis DATE: 18/06/23 23:56:06 GMT FROM: Phil Evans at U of Leicester J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA) and K.L. Page report on behalf of the Swift-XRT team: We have analysed 7.7 ks of XRT data for GRB 180623A (Page et al. GCN Circ. 22828), from 83 s to 18.2 ks after the BAT trigger. The data comprise 90 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 22829). The late-time light curve (from T0+4.5 ks) can be modelled with a power-law decay with a decay index of alpha=1.72 (+/-0.14). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.73 (+0.20, -0.19). The best-fitting absorption column is 6.4 (+/-0.7) x 10^22 cm^-2, in excess of the Galactic value of 1.5 x 10^22 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.04 (+0.27, -0.25) and a best-fitting absorption column of 6.6 (+/-0.9) x 10^22 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 9.0 x 10^-11 (2.9 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.6 (+/-0.9) x 10^22 cm^-2 Galactic foreground: 1.5 x 10^22 cm^-2 Excess significance: 9.9 sigma Photon index: 2.04 (+0.27, -0.25) If the light curve continues to decay with a power-law decay index of 1.72, the count rate at T+24 hours will be 2.3 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0 x 10^-13 (6.5 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/00844015. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22831 SUBJECT: GRB 180623A: Swift/UVOT Detection DATE: 18/06/24 13:58:14 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 180623A 86 s after the BAT trigger (Page et al., GCN Circ. 22828). A source consistent with the XRT position (Evans et al. GCN Circ. 22829) is detected in the initial UVOT exposures. The UVOT refined position is ra, deg = 214.5288,-60.2541 deg which is RA = 14:18:06.9 Dec = -60:15:14.8 with an estimated uncertainty of 1". Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 86 236 150 >20.68 white 878 997 119 20.04 +/- 0.24 v 629 6296 432 >19.2 b 18042 18207 162 19.86 +/- 0.28 u 299 17732 2252 >21.6 w1 678 16819 1318 >20.8 m2 653 6501 432 >20.0 w2 604 6092 432 >20.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 7.04 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22833 SUBJECT: GRB 180623A: Swift-BAT refined analysis DATE: 18/06/24 15:48:24 GMT FROM: Amy Lien at GSFC S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), K. L. Page (U Leicester), 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+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180623A (trigger #844015) (Page et al., GCN Circ. 22828). The BAT ground-calculated position is RA, Dec = 214.528, -60.268 deg which is RA(J2000) = 14h 18m 06.8s Dec(J2000) = -60d 16' 05.6" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 63%. The mask-weighted light curve shows a multi-peaked structure that starts at ~T-60 s and ends at ~T+115 s. The three main peaks occur at ~T0, ~T+25 s, and ~T+60 s, respectively. T90 (15-350 keV) is 114.9 +- 6.8 sec (estimated error including systematics). Note that the burst entered the BAT FOV around ~ T-90 s. Therefore, there might be additional burst emission beforehand. The time-averaged spectrum from T-61.8 to T+114.1 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.45 +- 0.04. The fluence in the 15-150 keV band is 1.2 +- 0.02 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+59.11 sec in the 15-150 keV band is 5.6 +- 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/844015/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22834 SUBJECT: GRB 180623A: retraction of the Swift/UVOT Detection DATE: 18/06/24 18:46:53 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Source reported in our previous GCN Circ. No 22831 is in fact a source present in the DSS survey. The extinction of this bursts is very high, so there is no afterglow seen. Our apologies for this error. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22856 SUBJECT: Konus-Wind observation of GRB 180623A DATE: 18/06/26 12:44:39 GMT FROM: Anna Kozlova at Ioffe Institute A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 180623A (Swift detection: Page et al., GCN Circ. 22828; Swift-BAT refined analysis: Barthelmy et al., GCN Circ. 22833) triggered Konus-Wind at T0=60141.775 s UT (16:42:21.775). The burst light curve shows a multipeaked structure started at ~T0-69 s with a total duration of ~114 s. The emission is seen up to ~2 MeV. As observed by Konus-Wind, the burst had a fluence of 3.15(-0.24,+0.28)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+2.208 s, of 2.94(-0.98,+1.01)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+49.408 s) is best fit in the 20 keV - 4 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.03(-0.16,+0.17) and Ep = 233(-33,+48) keV (chi2 = 63/70 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.1 (chi2 = 61/69 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+8.448 s) is best fit in the 20 keV - 4 MeV range by a power law with exponential cutoff model with alpha = -0.78(-0.17,+0.19) and Ep = 390(-63,+91) keV (chi2 = 59/70 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.3 (chi2 = 59/69 dof). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180623_T60141/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.