//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19211 SUBJECT: GRB 160321A: Swift detection of a probable burst DATE: 16/03/21 16:11:48 GMT FROM: Scott Barthelmy at NASA/GSFC M. Stamatikos (OSU/NASA/GSFC), S. D. Barthelmy (GSFC), A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU), S. B. Cenko (GSFC), P. D'Avanzo (INAF-OAB), P.A. Evans (U Leicester), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL), L. M. McCauley (PSU), A. Melandri (INAF-OAB), B. Mingo (U Leicester), K. L. Page (U Leicester), T. G. R. Roegiers (PSU), T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 15:55:27 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160321A (trigger=680017). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 99.414, +5.715, which is RA(J2000) = 06h 37m 39s Dec(J2000) = +05d 42' 53" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a few weak peaks with a total duration of about 35 sec. The peak count rate was ~700 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 15:57:18.0 UT, 110.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 99.4192, 5.7474 which is equivalent to: RA(J2000) = 06h 37m 40.60s Dec(J2000) = +05d 44' 50.8" with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 118 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 7.16 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 114 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 none 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 list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain extinction expected. Due to the proximity of the source to the Galactic plane (lat = -0.43 degrees) we cannot determine whether this is a Galactic source or a GRB, based on the immediately available data. Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 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: 19212 SUBJECT: GRB 160321A: MASTER observations zero Galaxy latitude GRB DATE: 16/03/21 17:01:43 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik Kislovodsk Solar Station of the Pulkovo Observatory K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory 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) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Kislovodsk was pointed to the GRB160321A 6 sec after notice time and 68 sec after trigger time at 2016-03-21 15:56:35 UT. We do not found optical transient within SWIFT error-box (Stamatikos et al., GCN 60321A) brighter then 13.1. After Sunset we found: Pro.type Date time Exp.time Limit Filt. Tube. Alert 2016-03-21 16:43:44 180 18.6 W WEST Alert 2016-03-21 16:43:44 180 18.1 W EAST Alert 2016-03-21 16:40:18 180 18.6 W WEST Alert 2016-03-21 16:36:45 180 18.6 W WEST Alert 2016-03-21 16:36:45 180 18.1 W EAST Alert 2016-03-21 16:33:16 180 18.5 W WEST Alert 2016-03-21 16:28:25 180 17.6 P WEST Alert 2016-03-21 16:28:25 180 17.6 P EAST Alert 2016-03-21 16:21:39 180 17.4 P EAST The galaxy latitude is about zero. So this is the optical free GRB. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19213 SUBJECT: GRB 160321A: Enhanced Swift-XRT position DATE: 16/03/21 22:10:03 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 1066 s of XRT Photon Counting mode data and 2 UVOT images for GRB 160321A, 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 = 99.41970, +5.74771 which is equivalent to: RA (J2000): 06h 37m 40.73s Dec (J2000): +05d 44' 51.8" with an uncertainty of 1.7 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: 19215 SUBJECT: GRB 160321A: Swift-XRT refined Analysis DATE: 16/03/22 13:09:34 GMT FROM: Phil Evans at U of Leicester A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and M. Stamatikos report on behalf of the Swift-XRT team: We have analysed 8.9 ks of XRT data for GRB 160321A (Stamatikos et al. GCN Circ. 19211), from 96 s to 58.6 ks after the BAT trigger. The data comprise 31 s in Windowed Timing (WT) mode (the first 8 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 Beardmore et al. (GCN Circ. 19213). The light curve can be modelled with a power-law decay with a decay index of alpha=2.36 (+0.13, -0.11). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.45 (+0.33, -0.30). The best-fitting absorption column is 9.3 (+3.8, -2.1) x 10^21 cm^-2, consistent with the Galactic value of 7.2 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 6.5 x 10^-11 (8.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 9.3 (+3.8, -2.1) x 10^21 cm^-2 Galactic foreground: 7.2 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.45 (+0.33, -0.30) If the light curve continues to decay with a power-law decay index of 2.36, the count rate at T+24 hours will be 1.2 x 10^-6 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.0 x 10^-17 (1.1 x 10^-16) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00680017. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19216 SUBJECT: GRB 160321A: Swift-BAT refined analysis DATE: 16/03/22 14:47:19 GMT FROM: Takanori Sakamoto at AGU H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), 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-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 160321A (trigger #680017) (Stamatikos, et al., GCN Circ. 19211). The BAT ground-calculated position is RA, Dec = 99.420, 5.753 deg which is RA(J2000) = 06h 37m 40.7s Dec(J2000) = +05d 45' 09.3" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The mask-weighted light curve shows a single-pulse structure that starts at ~ T0-22 sec, peaks at ~ T+2 sec, and ends at ~ T+23 sec. T90 (15-350 keV) is 33.6 +- 4.8 sec (estimated error including systematics). The time-averaged spectrum from T-20.9 to T+19.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.89 +- 0.19. The fluence in the 15-150 keV band is 5.3 +- 0.7 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+2.17 sec in the 15-150 keV band is 0.5 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Based on the ground analysis result, this event is very likely a GRB. However, given that it is on the Galactic Plane (lat = -0.43 deg.), we cannot rule out a galactic origin. We note that the BAT time averaged spectrum is soft but still in the typical range for BAT GRBs. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/680017/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19217 SUBJECT: GRB 160321A: Swift/UVOT Upper Limits DATE: 16/03/22 15:04:48 GMT FROM: Sam Emery at MSSL-UCL S.W.K. Emery (UCL-MSSL) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160321A 115 s after the BAT trigger (Stamatikos et al., GCN Circ. 19211). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 19213) 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 115 265 147 >20.4 u_FC 273 523 246 >19.7 white 115 6458 546 >21.1 v 603 6870 452 >19.5 b 529 6253 255 >20.1 u 273 12683 570 >20.1 w1 652 12607 1141 >20.2 m2 627 11700 1205 >20.1 w2 579 6664 452 >19.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.75 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19218 SUBJECT: GRB 160321A: Possible RATIR Optical and NIR Detections DATE: 16/03/22 17:14:25 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 (GSFC/STScI), 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 160321A (Stamatikos, et al., GCN 19211) 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 2016/03 22.14 to 2016/03 22.29 UTC (11.32 to 15.08 hours after the BAT trigger), obtaining a total of 2.47 hours exposure in the r and i bands and 0.82 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle (Beardmore, et al., GCN 19213), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following weak detections and upper limits (3-sigma): r > 23.84 i = 22.32 +/- 0.11 Z = 22.49 +/- 0.34 Y > 22.19 J > 21.53 H > 21.27 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. Further analysis is ongoing. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19219 SUBJECT: GRB 160321A: AbAO optical observations DATE: 16/03/22 20:25:03 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Volnova (IKI), R. Inasaridze (AbAO), V. Ayvazian (AbAO), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of Swift GRB 160321A (Stamatikos et al., GCN 19211) with AS-32 (0.7m) telescope of Abastumani Observatory starting on Mar. 21 (UT) 16:26:45. We obtained several unfiltered images of the field. We do not detect any source within enhanced XRT error circle (Beardmore et al., GCN 19213) down to 21.9m. A probable source (S/N = 2) detected 3.5 arcsec South from the center of XRT error circle (Beardmore et al., GCN 19213) in coordinates (J2000) 06:37:40.74 +05:44:48.2 +/- 0.5 arcsec in both coordinates. Preliminary photometry of the field is following Date UT start t-T0 Filter Exp. UL (3 sigma) (mid, days) (s) 2016-03-21 16:26:45 0.06839 none 41*120 21.9 Photometry is based on nearby USNO-B1.0 stars USNO-B1_id R2 0956-0104166 16.23 0957-0105913 15.38 0957-0106394 14.58 0956-0104566 15.41 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19452 SUBJECT: GRB 160321A: 15 GHz upper limits from AMI DATE: 16/05/24 14:54:40 GMT FROM: Kunal Mooley at Oxford U K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), C. Rumsey, D. Titterington, S. 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 160321A (Stamatikos et al., GCN 19211) 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 Mar 21.70, Mar 22.85, Mar 24.74, Mar 29.66, and Mar 31.68 (UT) do not reveal any radio source at the XRT location (Beardmore et al., GCN 19213), with 3sigma upper limits of 195 uJy, 261 uJy, 162 uJy, 207 uJy, and 189 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/.