//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20944 SUBJECT: GRB 170330A: Swift detection of a burst DATE: 17/03/30 22:43:47 GMT FROM: Scott Barthelmy at NASA/GSFC P. D'Avanzo (INAF-OAB), S. D. Barthelmy (GSFC), A. Cholden-Brown (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 22:29:51 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170330A (trigger=744773). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 283.326, -13.437, which is RA(J2000) = 18h 53m 18s Dec(J2000) = -13d 26' 12" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 10 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~3 sec after the trigger. The XRT began observing the field at 22:31:29.6 UT, 98.4 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 283.3323, -13.4301 which is equivalent to: RA(J2000) = +18h 53m 19.75s Dec(J2000) = -13d 25' 48.4" with an uncertainty of 5.9 arcseconds (radius, 90% containment). This location is 33 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 150 seconds with the White filter starting 108 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. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the sub-image. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the region. No correction has been made for the expected extinction corresponding to E(B-V) of 0.45. Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it). 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: 20945 SUBJECT: GRB 170330A: Prompt enhanced Swift-XRT position DATE: 17/03/30 23:13:06 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 170330A, we find an enhanced XRT position of the afterglow: RA, Dec: 283.3308, -13.4310 which is equivalent to: RA (J2000) = 18 53 19.39 Dec (J2000) = -13 25 51.7 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/744773. 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: 20954 SUBJECT: GRB 170330A: LCO Cerro Tololo observations DATE: 17/03/31 11:29:20 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc (U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large collaboration report: We observed Swift GRB 170330A (D'Avanzo et al. GCN 20944) on March 31, 07:00 UT (8.5 hours since the GRB) with one 1-m LCO unit in Cerro Tololo with the SDSS i filter. Comparing with the PanSTARRS archive data, within the XRT error circle we do not find any new/variable source down to i>20.5 mag (with a total exposure of 10x120s at 8.7 hours mid time) as calibrated against nearby PanSTARRS sources. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20959 SUBJECT: GRB 170330A: Swift/UVOT Detection of a Fading Afterglow DATE: 17/03/31 15:32:32 GMT FROM: Sam Emery at MSSL-UCL S.W.K. Emery (UCL-MSSL) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 170330A 109 s after the BAT trigger (D'Avanzo et al., GCN Circ. 20944). A fading source consistent with the XRT position (Evans GCN Circ. 20945) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 18:53:19.36 = 283.33067 (deg.) Dec (J2000) = -13:25:51.2 = -13.43090 (deg.) with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence). 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_FC 109 258 147 18.42 +/- 0.08 u_FC 266 516 246 >19.9 white 547 1368 225 19.94 +/- 0.21 v 596 1418 97 >18.4 b 522 1344 78 >19.3 u 266 1484 336 >20.0 w1 646 1467 97 >19.0 m2 621 1442 97 >18.9 w2 572 1393 78 >19.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.45 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20961 SUBJECT: GRB 170330A: Enhanced Swift-XRT position DATE: 17/03/31 16:39:38 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 3111 s of XRT Photon Counting mode data and 6 UVOT images for GRB 170330A, 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 = 283.33044, -13.43115 which is equivalent to: RA (J2000): 18h 53m 19.30s Dec (J2000): -13d 25' 52.1" 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: 20963 SUBJECT: GRB 170330A: Swift-XRT refined Analysis DATE: 17/03/31 18:51:53 GMT FROM: Phil Evans at U of Leicester J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N. Burrows (PSU), A. Cholden-Brown (PSU), S. J. LaPorte (PSU), B. Mingo (U. Leicester) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team: We have analysed 7.3 ks of XRT data for GRB 170330A, from 89 s to 53.1 ks after the BAT trigger. The data comprise 404 s in Windowed Timing (WT) mode (the first 7 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The light curve can be modelled with an initial power-law decay with an index of alpha=0.71 (+0.07, -0.06), followed by a break at T+439 s to an alpha of 1.061 (+0.029, -0.025). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.00 (+/-0.10). The best-fitting absorption column is 4.0 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 3.0 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.88 (+0.12, -0.11) and a best-fitting absorption column of 4.0 (+/-0.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.2 x 10^-11 (6.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.0 (+/-0.6) x 10^21 cm^-2 Galactic foreground: 3.0 x 10^21 cm^-2 Excess significance: 2.6 sigma Photon index: 1.88 (+0.12, -0.11) If the light curve continues to decay with a power-law decay index of 1.061, the count rate at T+24 hours will be 0.021 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.7 x 10^-13 (1.3 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00744773. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20968 SUBJECT: GRB 170330A: Swift-BAT refined analysis DATE: 17/04/01 06:16:03 GMT FROM: Amy Lien at GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), P. D'Avanzo (INAF-OAB), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), 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 170330A (trigger #744773) (D'Avanzo et al., GCN Circ. 20944). The BAT ground-calculated position is RA, Dec = 283.331, -13.458 deg which is RA(J2000) = 18h 53m 19.4s Dec(J2000) = -13d 27' 29.2" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 46%. The mask-weighted light curve shows a multi-peaked structure that lasts until ~T+126 s, with the main peak occurs around ~T-135 s. The burst came into the BAT field of view at ~T-170 s during a pre-planned spacecraft slew. Therefore, the burst emission might have started before ~T-170 s. T90 (15-350 keV) is 144.73 +- 3.51 sec (estimated error including systematics). The time-averaged spectrum from T-143.2 to T+126.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.38 +- 0.09. The fluence in the 15-150 keV band is 5.6 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-134.71 sec in the 15-150 keV band is 4.5 +- 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/744773/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20969 SUBJECT: GRB 170330A: AstroSat CZTI detection DATE: 17/04/01 12:19:52 GMT FROM: Vidushi Sharma at IUCAA V. Sharma (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data showed clear detection of GRB 170330A (Swift burst detection: P. D'Avanzo et al., GCN Circ. 20944) in the 40-200 keV energy range. The light curve shows multiple peak structure with peak counts at 22:27:36.000 UT, around ~35 s after the Swift trigger time i.e. ~T-170 s (Swift-BAT refined analysis: A. Y. Lien et al., GCN Circ. 20968) and it also coincides with the Swift main peak. The light curve doesn't show excess counts above the background for last ~100 s. The measured peak count rate is 163.2 counts/s above the background in combined data of four quadrants, with a total 1389 counts. The local mean background count rate was 358.8 counts/s. Using cumulative rates, we measure a T90 of 15.6 s. It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range. 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: 20974 SUBJECT: Konus-Wind observation of GRB 170330A DATE: 17/04/03 15:28:48 GMT FROM: Anna Kozlova at Ioffe Institute A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 170330A (Swift-BAT trigger #744773: D'Avanzo et al., GCN 20944; Lien et al., GCN 20968; AstroSat CZTI detection: Sharma et al., GCN 20969) triggered Konus-Wind at T0=80850.946 s UT (22:27:30.946). The burst light curve shows a single multi-peaked pulse with a total duration of ~12 s. The emission is seen up to ~5 MeV. As observed by Konus-Wind, the burst had a fluence of 1.85(-0.54,+0.42)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+4.912 s, of 4.91(-2.23,+2.17)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+8.448 s) is best fit in the 20 keV - 5 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.22(-0.67,+0.88), the high energy photon index beta = -1.98(-0.84,+0.17), the peak energy Ep = 226(-66,+190) keV (chi2 = 69/76 dof) The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170330_T80850/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20979 SUBJECT: GRB 170330A CALET Gamma-Ray Burst Monitor detection DATE: 17/04/04 23:27:52 GMT FROM: Takanori Sakamoto at AGU A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena) and the CALET collaboration: The long-duration GRB 170330A (D'Avanzo et al. GCN Circ. 20944; Sharma et al. GCN Circ. 20969; Kozlova et al. GCN Circ. 20974) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 22:27:27.91 on 30 March 2017. The burst signal was seen by all CGBM instruments. The light curve of the SGM shows several peaks. The bright burst episode starts at T-5 sec and ends at T+20 sec. Two late time emissions at T+120 s and T+150 s, which triggered Swift/BAT, are barely visible in the HXM data. The T90 duration measured by the SGM data is 18.5 +- 2.4 sec (40-1000 keV). The light curve is available at http://cgbm.calet.jp/cgbm_trigger/flight/1174947694/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.