//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19926 SUBJECT: GRB 160917A: Swift detection of a burst DATE: 16/09/17 11:46:10 GMT FROM: Scott Barthelmy at NASA/GSFC J. L. Racusin (NASA/GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU), D. Malesani (DARK/NBI and DTU Space), F. E. Marshall (NASA/GSFC), B. Mingo (U Leicester), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Swift Team: At 11:30:19 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160917A (trigger=712505). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 295.671, +46.399 which is RA(J2000) = 19h 42m 41s Dec(J2000) = +46d 23' 56" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several overlapping peaks with a total duration of about 25 sec. The peak count rate was ~2300 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 11:31:52.9 UT, 93.6 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 295.66805, 46.40321 which is equivalent to: RA(J2000) = 19h 42m 40.33s Dec(J2000) = +46d 24' 11.6" with an uncertainty of 4.2 arcseconds (radius, 90% containment). This location is 16 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. No spectrum from the promptly downlinked event data is yet available to determine the column density. The initial flux in the 2.5 s image was 7.72e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 125 seconds with the White filter starting 99 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. Results from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.16. Burst Advocate for this burst is J. L. Racusin (judith.racusin AT 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: 19927 SUBJECT: GRB 160917A: Enhanced Swift-XRT position DATE: 16/09/17 14:58:00 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 77 s of XRT Photon Counting mode data and 1 UVOT images for GRB 160917A, 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 = 295.66637, +46.40368 which is equivalent to: RA (J2000): 19h 42m 39.93s Dec (J2000): +46d 24' 13.2" with an uncertainty of 2.5 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: 19928 SUBJECT: GRB 160917A: OSN I-band upper limits DATE: 16/09/17 20:49:18 GMT FROM: Zach Cano at U of Iceland A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), Z. Cano (IAA-CSIC) & F. Aceituno (IAA-CSIC) report on behalf of a larger collaboration: We observed the field of GRB 160917A (Racusin et al.; GCN Circ. 19926) with the 1.5-m OSN telescope in Granada, Spain. We began observing at 19:08:34 UT (7.64 hours after the GRB onset), and obtained 14x300s images in I-band. In our coadded image, we find no new source in the refined XRT error circle (Evans et al; GCN Circ. 19927) down to a a 3-sigma limit of I(Vega) = 22.6. The calibration was performed using a nearby star in the USNO B1 catalog, and the upper limit corresponds to an isolated point source in our co-added image. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19929 SUBJECT: GRB 160917A: Mondy optical observations DATE: 16/09/17 21:11:04 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), E. Mazaeva (IKI), I. Korobtsev (ISTP) report on behalf of larger GRB follow-up collaboration: We observed the field of the GRB 160917A (Racusin et al. GCN 19926) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Sep., 17 (UT) 14:30:30. We obtained several images in R-filter. We detected the optical source within enhanced XRT error circle (Evans et al., GCN 19927) in coordinates (J2000) 19 42 39.81 +46 24 12.1 with uncertainities of 0.4 arcsec in both coordinates. Preliminary photometry of the afterglow is following Date UT start t-T0 Filter Exp. OT UL (3 sigma) (mid, days) (s) 2016-09-17 14:30:30 0.14601 R 120*30 20.60 +/- 0.20 22.9 Photometry is based on nearby USNO-B1.0 stars ID RA Dec R2 1 1363-0324591 19:42:38.95 +46:23:53.8 16.62 2 1364-0326339 19:42:40.68 +46:24:37.0 17.40 3 1363-0324630 19:42:42.78 +46:23:28.7 17.05 We suggest the source as optical afterglow of GRB 160917A. The finding chart can be found at http://grb.rssi.ru/GRB160917A/160917A_Mondy_fc.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19930 SUBJECT: GRB 160917A: Swift-XRT refined Analysis DATE: 16/09/17 22:43:12 GMT FROM: Phil Evans at U of Leicester S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), L.M. McCauley (PSU) and J.L. Racusin report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 160917A (Racusin et al. GCN Circ. 19926), from 80 s to 17.4 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. 19927). The light curve can be modelled with a power-law decay with a decay index of alpha=1.243 (+0.030, -0.029). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.81 (+0.22, -0.21). The best-fitting absorption column is 2.8 (+1.1, -0.9) x 10^21 cm^-2, in excess of the Galactic value of 1.7 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 4.1 x 10^-11 (5.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.8 (+1.1, -0.9) x 10^21 cm^-2 Galactic foreground: 1.7 x 10^21 cm^-2 Excess significance: 2.0 sigma Photon index: 1.81 (+0.22, -0.21) If the light curve continues to decay with a power-law decay index of 1.243, the count rate at T+24 hours will be 2.8 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-13 (1.5 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/00712505. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19931 SUBJECT: GRB 160917A: Swift/UVOT Detection DATE: 16/09/17 23:54:38 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and J. L. Racusin (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160917A 100 s after the BAT trigger (Racusin et al., GCN Circ. 19926). The refined XRT position (Evans et al. GCN Circ. 19927) is close to a bright star. However, a faint GRB candidate has been found at an offset of 6.5 arcsec to the south east from the bright star in the u exposures. The UVOT candidate position is: RA, Dec = 295.66687, 46.40368 (J2000) which is : RA = 19:42:40.049 Dec = +46:24:13.25 with an estimated accuracy of 1.5 arcsec. Preliminary detections 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 100 224 123 >21.01 b 4222 4422 100 >20.64 u 4017 5545 146 20.47 +- 0.36 v 3402 5038 200 >19.77 uvw1 3812 5448 200 >20.16 uvm2 3606 5242 100 >19.97 uvw2 4633 4833 200 >19.70 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.16 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19932 SUBJECT: GRB 160917A: Fermi GBM observation DATE: 16/09/18 00:33:54 GMT FROM: Peter Veres at UAH P Veres (UAH), A von Kienlin (MPE) and C Meegan (UAH) report on behalf of the Fermi GBM Team: "At 11:30:19.286 UT on 17 September 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 160917A (trigger 495804623 / 160917479). which was also detected by the Swift/BAT ​ ​ (Racusin et al., GCN 19926). ​ ​ The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 46 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 47 s (50-300 keV). The time-averaged spectrum from T0 to T0+14.1 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.00 +/- 0.05 and the cutoff energy, parameterized as Epeak, is 1604 +/- 357 keV. The event fluence (10-1000 keV) in this time interval is (7.2 +/- 0.3)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0 in the 10-1000 keV band is 5.1 +/- 0.2 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: 19933 SUBJECT: GRB 160917A: RATIR Optical and NIR Observations DATE: 16/09/18 16:31:29 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), 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 160917A (Racusin, et al., GCN 19926) 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 2016/09 18.12 to 2016/09 18.36 UTC (15.39 to 21.08 hours after the BAT trigger), obtaining a total of 3.72 hours exposure in the r and i bands and 1.63 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle (Evans et al., GCN 19927), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma): r > 24.31 i > 24.28 Z > 23.20 Y > 22.90 J > 22.57 H > 22.20 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: 19934 SUBJECT: GRB 160917A: Swift-BAT refined analysis DATE: 16/09/18 17:51:36 GMT FROM: Jay R. Cummings at Swift H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), 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-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 160917A (trigger #712505) (Racusin, et al., GCN Circ. 19926). The BAT ground-calculated position is RA, Dec = 295.652, 46.400 deg which is RA(J2000) = 19h 42m 36.4s Dec(J2000) = +46d 23' 59.3" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 43%. The mask-weighted light curve shows an initial bright peak about 1 second long with some structure on finer time scales, and variable emission for another 30 seconds. Another weak peak occurs from T+50 to T+90 seconds. T90 (15-350 keV) is 16 +- 2 sec (estimated error including systematics). The time-averaged spectrum from T-0.34 to T+15.31 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.89 +- 0.15. The fluence in the 15-150 keV band is 1.3 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band is 2.2 +- 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/712505/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19936 SUBJECT: GRB 160917A: Mondy afterglow confirmation DATE: 16/09/19 20:12:31 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), E. Mazaeva (IKI), I. Korobtsev (ISTP) report on behalf of larger GRB follow-up collaboration: We observed the field of the GRB 160917A (Racusin et al. GCN 19926) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Sep., 18 (UT) 15:25:21. We obtained several images in R-filter. We do not detect the optical source reported as afterglow candidate (Volnova et al. GCN 19929; Kuin et al. GCN 19931). Preliminary photometry of the field is following Date UT start t-T0 Filter Exp. OT UL (3 sigma) (mid, days) (s) 2016-09-18 15:25:21 1.18522 R 60*60 n/d 22.0 Photometry is based on nearby USNO-B1.0 stars used in GCN circ. 19929. In comparison with our previous observation (Volnova et al. GCN 19929) the source is not visible up to 22.0 mag. The source faded between two epochs on at least 1.4 magnitudes and it is most probably the afterglow of GRB 160917A. Our observation is compatible with more deep RATIR observation in r-filter (Butler et al. GCN 19933). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19942 SUBJECT: GRB160917A: AstroSat CZTI detection DATE: 16/09/27 03:14:26 GMT FROM: Varun Bhalerao at IUCAA V. Bhalerao (IUCAA), V. Kumar (IUCAA), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration: Analysis of Astrosat data showed the CZTI detection of GRB160917A (Swift BAT detection: S.Barthelmy et al., GCN Circ. 19926). The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak at 11:30:25.0 UT, 6 seconds after Swift Trigger at 11:30:19.0 UT. The peak count rate was 116.0 counts/sec above the background (four quadrants summed together), with a total of 1008.0 counts. The local mean background count rate was 327.0 counts/sec. Using cumulative rates, we measure a T90 of 21 sec. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb . CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19951 SUBJECT: GRB 160917A: 15 GHz upper limits from AMI DATE: 16/09/27 16:33:39 GMT FROM: Kunal Mooley at Oxford U K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester) The AMI Large Array robotically triggered on the Swift alert for GRB 160917A (Racusin et al., GCN 19926) as part of the 4pisky program, and subsequent follow up observations were obtained up to 10 days post-burst. Our observations at 15 GHz on 2016 Sep 17.65, Sep 20.87, and Sep 24.87 (UT) do not reveal any radio source at the XRT location (Evans et al., GCN 19927), with 3sigma upper limits of 150 uJy, 84 uJy, and 90 uJy respectively. We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19990 SUBJECT: GRB 160917A: Lomonosov BDRG gamma ray detection DATE: 16/10/05 11:48:14 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs N.L.Dzhioeva,V.V.Bogomolov, S.I.Svertilov, A.M.Amelushkin, V.O.Barinova, M.I.Panasyuk, A.V.Bogomolov, A.F.Iyudin, V.V.Kalegaev, D.Nguen, V.L. Petrov, I.V.Yashin, P.S.Kazarian Physics Department, Skobel`tsyn Institute of Nuclear Physics, Moscow State V. Lipunov, E.S. Gorbovskoy, N.Tyurina, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute I. Park, J. Lee, S. Jeong Department of Physics, Sungkyunkwan University, Seobu-ro, Jangangu, Suwonsi, Korea At 11:30:20 UT on 17 Sep 2016, the Lomonosov BDRG Gamma-ray Burst Monitor (http://lomonosov.sinp.msu.ru/en/scientific-equipment-2/bdrg ) triggered GRB 160917A (J. L. Racusin, GCN 19962). GRB 160917A has several peaks LC, total duration 25s, the energy range 70-1000 keV. More information will be available at: http://lomonosov.sinp.msu.ru/category/results/observation-gamma-ray-bursts This Notice was ground-generated. The message may be cited.