//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24742 SUBJECT: GRB 190604B: Swift detection of a burst DATE: 19/06/04 15:16:35 GMT FROM: Kim Page at U.of Leicester K. L. Page (U Leicester), S. D. Barthelmy (GSFC), J.D. Gropp (PSU), N. J. Klingler (PSU), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU), D. M. Palmer (LANL), B. Sbarufatti (PSU), M. H. Siegel (PSU), K. K. Simpson (PSU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 14:57:15 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190604B (trigger=906654). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 297.587, -32.932 which is RA(J2000) = 19h 50m 21s Dec(J2000) = -32d 55' 56" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 250 sec, with two major peaks at ~T0 and ~T+155 s. The peak count rate was ~4000 counts/sec (15-350 keV), at ~155 sec after the trigger. The XRT began observing the field at 14:59:12.5 UT, 116.8 seconds after the BAT trigger. Using promptly downlinked data we find a bright, variable uncatalogued X-ray source located at RA, Dec 297.53804, -32.97663 which is equivalent to: RA(J2000) = 19h 50m 09.13s Dec(J2000) = -32d 58' 35.9" with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 218 arcseconds from the BAT onboard position. 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 1.36 x 10^21 cm^-2 (Willingale et al. 2013). The initial flux in the 0.1 s image was 1.11e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 126 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 0.14. 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24743 SUBJECT: GRB 190604B: Prompt enhanced Swift-XRT position DATE: 19/06/04 16:01:14 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 190604B, we find an enhanced XRT position of the afterglow: RA, Dec: 297.5413, -32.9782 which is equivalent to: RA (J2000) = 19 50 09.92 Dec (J2000) = -32 58 41.4 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/906654. 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: 24746 SUBJECT: GRB 190604B: Enhanced Swift-XRT position DATE: 19/06/04 18:43:37 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 206 s of XRT Photon Counting mode data and 1 UVOT images for GRB 190604B, 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 = 297.54058, -32.97803 which is equivalent to: RA (J2000): 19h 50m 9.74s Dec (J2000): -32d 58' 40.9" with an uncertainty of 1.9 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: 24747 SUBJECT: GRB190604B: Swift/UVOT detection DATE: 19/06/04 20:40:46 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (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 190604B 128 s after the BAT trigger (Page et al., GCN Circ. 24742). A faint source is detected in the initial white UVOT exposure at a position consistent with the enhanced XRT source position (Evans et al., GCN Circ. 24746). The preliminary detection 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 128 276 146 19.90 ± 0.24 white 618 812 39 >19.63 v 669 861 39 >17.95 b 594 787 39 >18.98 u 338 588 246 >19.71 uvw1 718 738 20 >17.44 uvw2 645 837 39 >18.09 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.15 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24748 SUBJECT: GRB190604B: GROWTH-India telescope followup - no optical counterpart found DATE: 19/06/04 21:31:40 GMT FROM: Harsh Kumar at Indian Inst of Tech,Bombay M. Khandagale, H. Kumar, V. Karambelkar, V. Bhalerao(IITB), G. C. Anupama, J. Stanzin (IIA) report on behalf of the GROWTH collaboration: We observed the field of GRB190604B reported by K. L. Page et al., GCN 24742 at 2019-06-04 and 20:03:18.675 UT with the 0.7m GROWTH-India telescope. We took 2 exposures of 600 seconds each in r filter. No source was found within an uncertainty region of 3.6 arcseconds to RA(J2000) = 19h 50m 09.13s, Dec(J2000) = -32d 58' 35.9" (K. L. Page et al.,GCN 24742). We obtained the following upper limits: ------------------------------------------------------------------ JD(Start)| Exposure(sec) | Filter | lim_Mag | ------------------------------------------------------------------ 2458639.335 | 600 | r | 20.33| 2458639.342 | 600 | r | 19.93| ------------------------------------------------------------------ The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24749 SUBJECT: GRB 190604B: Swift-XRT refined Analysis DATE: 19/06/05 02:39:36 GMT FROM: Phil Evans at U of Leicester J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernadini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , V. D'Elia (ASDC) and K.L. Page report on behalf of the Swift-XRT team: We have analysed 7.7 ks of XRT data for GRB 190604B (Page et al. GCN Circ. 24742), from 120 s to 34.4 ks after the BAT trigger. The data comprise 285 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. 24743). The late-time light curve (from T0+4.9 ks) can be modelled with a power-law decay with a decay index of alpha=0.94 (+/-0.12). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.40 (+/-0.03). The best-fitting absorption column is 1.49 (+0.16, -0.13) x 10^21 cm^-2, consistent with the Galactic value of 1.4 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.02 (+/-0.12) and a best-fitting absorption column of 3.0 (+/-0.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (5.4 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.0 (+/-0.5) x 10^21 cm^-2 Galactic foreground: 1.4 x 10^21 cm^-2 Excess significance: 5.7 sigma Photon index: 2.02 (+/-0.12) If the light curve continues to decay with a power-law decay index of 0.94, the count rate at T+24 hours will be 0.057 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.1 x 10^-12 (3.1 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/00906654. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24750 SUBJECT: GRB 190604B: BOOTES-3 early optical limits DATE: 19/06/05 05:52:15 GMT FROM: Alberto J. Castro-Tirado at IAA-CSIC Y.-D. Hu, X.-Y.Li, E. Fernandez-Garcia, A. Ayala and A. J. Castro-Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de Malaga), M. D. Caballero-Garcia (ASU-CAS, CZ) and R. Querel (NIWA), on behalf of a larger collaboration, report: The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New Zealand) automatically responded to the Swift GRB 190604B (Page et al. GCNC 24742) only 35 s after the burst). At the position of the Swift/XRT enhanced X-ray position (Evans et al. GCNC 24746), no optical afterglow is detected down to R = 15.5 (for the 1-s image gathered at 14:57:50 UT) or down to 19.8 mag (for the co-added 9x10s unfiltered images at mid-time 15:05:56 UT, i.e. 8.7 min after trigger). We thank the staff at NIWA for its excellent support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24752 SUBJECT: GRB 190604B: Swift-BAT refined analysis DATE: 19/06/05 14:50:33 GMT FROM: Amy Lien at GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), K. L. Page (U Leicester), 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+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 190604B (trigger #906654) (Page et al., GCN Circ. 24742). The BAT ground-calculated position is RA, Dec = 297.546, -32.975 deg which is RA(J2000) = 19h 50m 10.9s Dec(J2000) = -32d 58' 31.1" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 64%. The mask-weighted light curve shows a multi-peaked structure that starts from ~T-40 s and ends at ~T+240 s. There are two major peaks that occur at ~T0 and ~T+158 s, respectively. T90 (15-350 keV) is 220.2 +- 4.7 sec (estimated error including systematics). The time-averaged spectrum from T-39.776 sec to T+239.504 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.81 +- 0.04. The fluence in the 15-150 keV band is 1.77 +- 0.04 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+157.54 sec in the 15-150 keV band is 7.3 +- 0.4 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/906654/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24754 SUBJECT: GRB 190604B: Kitab observatory optical upper limit DATE: 19/06/05 19:24:37 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI), A. Novichonok (KIAM), A. Pozanenko (IKI), E. Mazaeva (IKI), A. Volnova (IKI), I. Molotov (KIAM), Sh. Ehgamberdiev (UBAI) report on behalf of larger IKI GRB FuN collaboration: We observed the field of the Swift GRB 190604B (Page et al., GCN 24742) with RC-36 0.36-m telescope of Kitab Observatory starting on June 04 (UT) 22:26:32 in Clear filter. We do not find any optical source within enhanced Swift-XRT position (Evans et al., GCN 24746). The non-detection is consistent with BOOTES-3 results (Hu et al., GCN 24750). Preliminary photometry of the field is following. Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2019-06-04 22:26:32 0.32068 CR 21*60 n/d n/d 18.6 The photometry is based on the nearby USNO-B1 (R2) stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24762 SUBJECT: GRB 190604B: VLT Afterglow Detection DATE: 19/06/06 16:39:16 GMT FROM: Alexander Kann at IAA-CSIC L. Izzo, D. A. Kann (both HETH/IAA-CSIC), D. B. Malesani (DTU Space), D. Hartmann (Clemson University), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), and N. R. Tanvir (Univ. Leicester) report on behalf of the Stargate Consortium: We observed the field of GRB 190604B (Page et al., GCN 24742) with X-shooter mounted on the ESO VLT UT2 (Kueyen). Images were obtained in SDSS g'r'z', as well as a deeper 300 s r' exposure, centered at 05:24:16 UT on June 05, 2019 (0.8483 days after the GRB trigger). At the position of the UVOT afterglow (Breeveld et al., GCN 24747) and within the XRT error circle (Evans et al., GCN 24746), we detect a faint source only in the latter image. Using a recent computation of the X-shooter acquisition camera zero-point value, the total number of counts, a seven arcsec radius aperture and the exposure time of 300 s, we derive a magnitude of r'(AB) = 23.27 +/- 0.09 mag. Because of source faintness, no spectroscopy was attempted.