//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18163 SUBJECT: GRB 150819A: Swift detection of a burst DATE: 15/08/19 01:02:15 GMT FROM: Scott Barthelmy at NASA/GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), S. B. Cenko (GSFC), V. D'Elia (ASDC), L. Izzo (URoma/ICRA), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 00:50:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150819A (trigger=652643). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 42.337, +9.784 which is RA(J2000) = 02h 49m 21s Dec(J2000) = +09d 47' 02" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for image triggers, the real-time light curve does not show anything significant. The XRT began observing the field at 00:52:27.1 UT, 138.1 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 42.33146, 9.80665 which is equivalent to: RA(J2000) = 02h 49m 19.55s Dec(J2000) = +09d 48' 23.9" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 83 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 consistent with the Galactic value of 1.85 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 142 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 0.22. Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 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: 18165 SUBJECT: GRB 150819A: Prompt enhanced Swift-XRT position DATE: 15/08/19 01:29:35 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Using promptly downlinked XRT event data for GRB 150819A, we find an enhanced XRT position of the afterglow: RA, Dec: 42.3335, 9.8075 which is equivalent to: RA (J2000) = 02 49 20.03 Dec (J2000) = +09 48 26.9 with an uncertainty of 2.0 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/652643. Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18167 SUBJECT: GRB 150819A: Enhanced Swift-XRT position DATE: 15/08/19 08:43:27 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 2467 s of XRT Photon Counting mode data and 4 UVOT images for GRB 150819A, 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 = 42.33310, +9.80748 which is equivalent to: RA (J2000): 02h 49m 19.94s Dec (J2000): +09d 48' 26.9" 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: 18168 SUBJECT: GRB 150819A: Swift/UVOT Upper Limits DATE: 15/08/19 10:22:34 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (UCL-MSSL) and T. N. Ukwatta (LANL) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150819A 143 s after the BAT trigger (Ukwatta et al., GCN Circ. 18163). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 18167) 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 143 292 147 >21.0 u_FC 301 551 246 >20.2 white 143 7062 569 >21.4 v 631 6037 274 >19.6 b 557 6857 274 >20.3 u 301 6652 501 >20.4 w1 680 6447 274 >20.0 m2 656 6242 274 >19.9 w2 607 7135 346 >20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.22 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18169 SUBJECT: GRB 150819A: MASTER-IAC early upper limit DATE: 15/08/19 10:46:45 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, P.Balanutsa,A.Kuznetsov,D.Kuvshinov, Lomonosov Moscow State University, Sternberg Astronomical Institute K.Ivanov, O.Gres, N.M.Budnev, S.Yazev, Irkutsk State University D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnih Ural Federal University, Kourovka Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in IAC was pointed to the GRB150819.03 25 sec after notice time and 100 sec after trigger time at 2015-08-19 00:51:51 UT. On our first (20s exposure) set we haven`t found optical transient within SWIFT error-box (Ukwatta, Barthelmy et al., GCN 18163; Evans, GCN 18165; Evans et al., GCN 18167). Zenit distance was aboute ~76 degrees. The 5-sigma upper limit has been about 17.5 mag Our results are: T_start T-Tmid Expt. Mlimit Coadd 00:51:51.6 112 20 17.5 1 00:51:51.6 163 90 18.0 3 00:54:05.5 337 180 18.9 3 00:51:51.6 536 760 19.8 10 01:06:31.0 1995 1800 20.4 10 The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18170 SUBJECT: GRB 150819A: Swift-BAT refined analysis DATE: 15/08/19 12:37:21 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (AGU), 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. M. Palmer (LANL), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 150819A (trigger #652643) (Ukwatta, et al., GCN Circ. `8`63). The BAT ground-calculated position is RA, Dec = 42.340, 9.787 deg, which is RA(J2000) = 02h 49m 21.5s Dec(J2000) = +09d 47' 11.6" with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 93%. the mask-weighted light curve shows a broad peaking starting at ~T+10 sec, peaking at ~T+40 sec, and ending at ~T+70 sec. T90 (15-350 keV) is 52.1 +- 12.9 sec (estimated error including systematics). The time-averaged spectrum from T+14.18 to T+73.46 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.72 +- 0.27. The fluence in the 15-150 keV band is 4.8 +- 0.9 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+17.70 sec in the 15-150 keV band is 0.3 +- 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/652643/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18172 SUBJECT: GRB 150819A: Swift-XRT refined Analysis DATE: 15/08/19 13:02:02 GMT FROM: Phil Evans at U of Leicester B.P. Gompertz (U. Leicester), A. D'ai (INAF-IASFPA), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and T.N. Ukwatta report on behalf of the Swift-XRT team: We have analysed 7.1 ks of XRT data for GRB 150819A (Ukwatta et al. GCN Circ. 18163), from 122 s to 34.3 ks after the BAT trigger. The data comprise 43 s in Windowed Timing (WT) mode (the first 9 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 Evans et al. (GCN Circ. 18165). The light curve can be modelled with a power-law decay with a decay index of alpha=1.62 (+/-0.09). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.42 (+0.24, -0.23). The best-fitting absorption column is 6.6 (+2.3, -1.9) x 10^21 cm^-2, in excess of the Galactic value of 1.8 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 6.1 x 10^-11 (7.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.6 (+2.3, -1.9) x 10^21 cm^-2 Galactic foreground: 1.8 x 10^21 cm^-2 Excess significance: 4.1 sigma Photon index: 1.42 (+0.24, -0.23) If the light curve continues to decay with a power-law decay index of 1.62, the count rate at T+24 hours will be 2.0 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-14 (1.6 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00652643. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18173 SUBJECT: GRB 150819A: RATIR Optical Observations DATE: 15/08/19 14:08:37 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report: We observed the field of GRB 150819A (Ukwatta et al., GCN 18163) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2015/08 19.33 to 2015/08 19.48 UTC (7.08 to 10.60 hours after the BAT trigger), obtaining a total of 2.80 hours exposure in the r and i bands. For a source within the enhanced Swift-XRT error circle (Evans et al., GCN 18165), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma): r > 23.60 i > 23.91 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18176 SUBJECT: IPN Triangulation of GRB 150819B (short / very intense) DATE: 15/08/19 21:52:08 GMT FROM: Dmitry Svinkin at Ioffe Institute S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, K. Hurley, on behalf of the IPN, V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa, and A. Goldstein, on behalf of the Fermi GBM team, and A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report: The short-duration, very intense GRB 150819B has been detected by Fermi (GBM trigger 461673203 / 150819440), Konus-Wind, and INTEGRAL (SPI-ACS), so far, at about 37999 s UT (10:33:19). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 59.386 (03h 57m 33s) +39.701 (+39d 42' 05") Corners: 59.157 (03h 56m 38s) +40.372 (+40d 22' 21") 59.671 (03h 58m 41s) +39.060 (+39d 03' 35") 59.608 (03h 58m 26s) +39.029 (+39d 01' 45") 59.093 (03h 56m 22s) +40.341 (+40d 20' 29") --------------------------------------------- The error box area is 272 sq. arcmin, and its maximum dimension is 1.4 deg (the minimum one is 3.4 arcmin). The Sun distance was 81 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB150819_T38000/IPN/ The time history and spectrum will be given in forthcoming GCN Circulars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18178 SUBJECT: GRB 150819B: Fermi GBM detection DATE: 15/08/20 02:15:28 GMT FROM: Eric Burns at U of Alabama H.-F. Yu (MPE) and E. Burns (UAH) report on behalf of the Fermi GBM Team: "At 10:33:19.50 UT on 19 August 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 150819B (trigger 461673203 / 150819440). The on-ground calculated location, using the GBM trigger data, is RA = 62.72, Dec = 40.60 (J2000 degrees, equivalent to 04h 10m 53s, 40d 36'), with an uncertainty of 2.2 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ). The trigger resulted in an Autonomous Repoint Request (ARR) by the GBM Flight Software owing to the high peak flux of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight location. The initial angle from the Fermi LAT boresight to the best location is 104 degrees . The GBM light curve consists of two pulses with a duration (T90) of about 0.96 s (50-300 keV). The time-averaged spectrum from T0-0.064 s to T0+0.896 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.04 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 532 +/- 27 keV The event fluence (10-1000 keV) in this time interval is (7.6 +/- 0.1)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.000 s in the 10-1000 keV band is 148.4 +/- 3.8 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: 18180 SUBJECT: Konus-Wind observation of GRB 150819B DATE: 15/08/20 12:46:07 GMT FROM: Dmitry Svinkin at Ioffe Institute S. Golenetskii, R. Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The short-duration, very intense GRB 150819B (IPN triangulation: Golenetskii et al., GCN 18176; Fermi GBM detection: Yu and Burns, GCN 18178) triggered Konus-Wind at T0=38000.750 s UT (10:33:20.750). The burst light curve shows at least three separate peaks. A total duration of the burst is ~1.2 s. The emission is seen up to ~3 MeV. As observed by Konus-Wind, the burst had a fluence of 6.61(-0.88,+1.10)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.008 s, of 1.20(-0.17,+0.19)x10^-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 5 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.03(-0.21,+0.24) and Ep = 348(-70,+116) keV (chi2 = 74/89 dof). Fitting by the GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.3 (chi2 = 74/88 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.064 s) is best fit in the 20 keV - 5 MeV range by a power law with exponential cutoff model with alpha = -0.41(-0.15,+0.17) and Ep = 618(-86,+95) keV (chi2 = 57/43 dof). Fitting by the GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.8 (chi2 = 57/42 dof). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB150819_T38000/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18181 SUBJECT: GRB150819A: NOT imaging DATE: 15/08/20 15:28:20 GMT FROM: Steve Schulze at U of Iceland S. Schulze (PUC, MAS), D. Malesani, J. P. U. Fynbo (DARK, NBI), J. Duus, T. Hinz-Berg, O. Busborg Jensen (NBI) and P. Jakobsson (U Iceland) report on behalf a larger collaboration: We observed the field of GRB 150819A (Ukwatta et al., GCN 18163) with the Nordic Optical Telescope (NOT) equipped with ALFOSC. We obtained 4 images in the I band and 3 images in the z band with an individual sub-exposure time of 300 s. Observations started at 02:01 UT on August 19 (i.e. 1.19 hr after the burst). We detect no credible source in the co-added I and z band images at the refined XRT localisation (Evans et al., GCN 18167). The limiting magnitude of the I-band image is 23 mag (3 sigma, Vega). This value is not corrected for foreground extinction. The flux calibration of the z-band image is still pending. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18193 SUBJECT: GRB 150819A: Mondy and TSHAO optical upper limits DATE: 15/08/21 23:11:50 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), E. Klunko (ISTP), I. Reva (Fesenkov Astrophysical Institute), A. Kusakin (Fesenkov Astrophysical Institute), A. Volnova (IKI), I. Korobtsev (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 150819A (Ukwatta et al., GCN 18163) with AZT-33IK telescope of Sayan observatory (Mondy) and Zeiss-1000 (West) 1-m telescope of Tien Shan Astronomical Observatory. We obtained several images in R-filter in each telescope. We do not detect any source within enhanced XRT error circle (Evans et al., GCN 18167). Upper limits of the field are following Date UT start t-T0 Filter Exp. UL(3 sigma) Telescope (mid, days) (s) 2015-08-19 19:06:09 0.78197 R 30*120 22.7 AZT-33IK 2015-08-19 21:57:51 0.89889 R 10*300 19.4 Zeiss-1000 Photometry is based on USNO-B1.0 stars: USNO-B.1_id R2 0997-0042082 17.56 0997-0042080 18.70