//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22589 SUBJECT: GRB 180404A: Swift detection of a burst with an optical afterglow DATE: 18/04/04 00:54:52 GMT FROM: David Palmer at LANL J.D. Gropp (PSU), D. N. Burrows (PSU), A. Deich (PSU), C. Gronwall (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 00:45:35 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180404A (trigger=821881). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 83.564, -37.170 which is RA(J2000) = 05h 34m 15s Dec(J2000) = -37d 10' 10" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 50 sec. The peak count rate was ~1900 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 00:47:02.1 UT, 86.5 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 83.54900, -37.16824 which is equivalent to: RA(J2000) = 05h 34m 11.76s Dec(J2000) = -37d 10' 05.7" with an uncertainty of 4.2 arcseconds (radius, 90% containment). This location is 43 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. UVOT took a finding chart exposure of 150 seconds with the White filter starting 89 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 05:34:11.63 = 83.54846 DEC(J2000) = -37:10:03.9 = -37.16774 with a 90%-confidence error radius of about 0.65 arc sec. This position is 2.3 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.40 with a 1-sigma error of about 0.16. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu). 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: 22590 SUBJECT: GRB 180404B: Swift detection of a burst with an optical counterpart DATE: 18/04/04 02:23:56 GMT FROM: David Palmer at LANL S. J. LaPorte (PSU), C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 02:11:44 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180404B (trigger=821902). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 53.384, -50.195 which is RA(J2000) = 03h 33m 32s Dec(J2000) = -50d 11' 41" 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 50 sec. The peak count rate was ~9000 counts/sec (15-350 keV), at ~9 sec after the trigger. The XRT began observing the field at 02:12:53.9 UT, 69.9 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 53.3967, -50.2151 which is equivalent to: RA(J2000) = +03h 33m 35.21s Dec(J2000) = -50d 12' 54.4" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 78 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 81 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 03:33:34.24 = 53.39265 DEC(J2000) = -50:12:54.1 = -50.21504 with a 90%-confidence error radius of about 0.76 arc sec. This position is 9.3 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.61 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01. Burst Advocate for this burst is S. J. LaPorte (extragsam 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: 22591 SUBJECT: GRB 180404A: VLT/X-shooter redshift DATE: 18/04/04 03:15:44 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst J. Selsing (DARK/NBI), D. Malesani (DAWN/NBI and DARK/NBI), D.A. Kann (HETH/IAA-CSIC), N.R. Tanvir (Univ. Leicester) report on behalf of the Stargate consortium: We observed the optical counterpart of GRB 180404A (Gropp et al., GCN 22589) using the ESO Very Large Telescope (VLT) UT2 equipped with the X-shooter spectrograph. Observations were carried out in robotic "rapid response mode" (RRM), initiated automatically following the X-ray localization notice. In the 15-s r-band acquisition image, taken on 2018 Apr 4.0423 UT (15.3 min after the trigger), the afterglow is clearly detected, at coordinates (J2000): RA = 05:34:11.67 Dec = -37:10:04.1 We measure a magnitude R = 18.64 +- 0.1 (Vega), calibrated against nearby USNO stars, where the error is dominated by the calibration scatter. Several spectra were acquired. We report here on the exposure with mid epoch Apr 4.0495 UT (that is, 25.6 min after the GRB), with 600 s exposure time, and covering the wavelength range 3000-25000 AA. The afterglow continuum trace is clearly detected. Superposed on it, several absorption features are visible, which we identify as Al III, Fe II, Mg II, and Mg I, all at a common redshift redshift of z = 1.000. We acknowledge excellent support from the observing staff at Paranal, in particular Stephane Brillant, Luca Sbordone, Andrea Mehner, and Jose Velasquez. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22592 SUBJECT: GRB 180404A: Enhanced Swift-XRT position DATE: 18/04/04 04:57:12 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 646 s of XRT Photon Counting mode data and 1 UVOT images for GRB 180404A, 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 = 83.54906, -37.16807 which is equivalent to: RA (J2000): 05h 34m 11.77s Dec (J2000): -37d 10' 05.1" with an uncertainty of 2.0 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: 22593 SUBJECT: GRB 180404A: MASTER-OAFA OT observation DATE: 18/04/04 05:30:33 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, A.Kuznetsov, V.Chazov, I. Gorbunov, D. Vlasenko, D.Kuvshinov, P.Balanutsa Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University R. Podesta, Carlos Lopez and F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) A. Tlatov, V.Senik, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk O. Gres, N.M. Budnev, O. Chuvalaev, Yu.Ishmuhametova Irkutsk State University R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias D. Buckley, S. Potter South African Astronomical Observatory MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Argentina was pointed to the GRB180404A (Gropp et al. GCN 22589) 21 sec after notice time and 43 sec after trigger time at 2018-04-04 00:46:18 UT. On our first 10s exposure set we haven`t found optical transient with 17.4 5-sigma upper limit in SWIFT XRT error-box (ra=83.549 dec=-37.17 r=4.2"). MASTER auto-detection system detected OT with RA,Dec=5h 34m 11s.66, -37d 10m 03s.5 with unfiltered m_OT=19.8 on the summary image with 660s exposition started 2018-04-04 00:46:18.938UT, that was discovered by Swift (Gropp et al. GCN 22589) and confirmed by VLT (Selsing et al. GCN 22591) ==================================================================== The observations made on zenit distance = 42 degrees, galaxy latitude b = -30 degree. The moon (87 % bright part) below the horizon (The altitude of the Moon is -1 degree ). The sun altitude is -29.7 degree. The message may be cited. 1 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22594 SUBJECT: GRB 180404B: Enhanced Swift-XRT position DATE: 18/04/04 08:18:28 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 305 s of XRT Photon Counting mode data and 1 UVOT images for GRB 180404B, 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 = 53.39268, -50.21550 which is equivalent to: RA (J2000): 03h 33m 34.24s Dec (J2000): -50d 12' 55.8" with an uncertainty of 2.9 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: 22596 SUBJECT: GRB 180404B: MASTER-OAFA OT observation DATE: 18/04/04 09:39:48 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, A.Kuznetsov, V.V.Chazov, A.V. Krylov, I. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University R. Podesta, F. Podesta, C. Lopez, C.Francile Observatorio Astronomico Felix Aguilar (OAFA) H.Levato, C. Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias D. Buckley South African Astronomical Observatory O. Gres, N.M. Budnev, Yu.Ishmuhametova Irkutsk State University A. Tlatov, V.Senik, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory A. Gabovich, V. Yurkov, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Argentina was pointed to the GRB180404B (LaPorte et al. GCN 22590; Beardmore et al. GCN 22594) 27 sec after notice time and 45 sec after trigger time at 2018-04-04 02:12:29 UT. On our first 10s exposure image with unfiltered mlim=16.5 (5-sigma) we don't found optical transient within SWIFT error-box (ra=53.3792 dec=-50.195 r=0.05 LaPorte et al. GCN 22590) MASTER auto-detection system detected OT with RA,Dec=53.392900; -50.214903 and unfiltered m_OT = 18.4 (automatic reduction) on the summary image with 670s exposition started on 2018-04-04 02:12:29 (mlim=19.7) The message may be cited. ==================================================================== The observations started at zenit distance = 73 degrees, galaxy latitude b = -51 degree. The moon (86 % bright part) is 16 degrees above the horizon. The distance between moon and object is 115 The sun altitude was -46.8 degree. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22597 SUBJECT: GRB 180404B: Fermi GBM observation DATE: 18/04/04 10:04:46 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 02:11:38.64 UT on 04 April 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180404B (trigger 544500703 / 180404091), which was also detected by the Swift/BAT (LaPorte et al. 2018, GCN 22590). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 61.3 degrees. The GBM light curve shows a single bright peak followed by a secondary emission episode with a duration (T90) of about 80 s (50-300 keV). The time-averaged spectrum from T0+0.003 s to T0+33.281 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -0.40 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 209 +/- 6 keV. The event fluence (10-1000 keV) in this time interval is (3.3 +/- 0.4)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+12.86 s in the 10-1000 keV band is 8.0 +/- 0.3 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 204 +/- 8 keV, alpha = -0.38 +/- 0.04 and beta = -3.3 +/- 0.6. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22598 SUBJECT: GRB 180404B: Swift-XRT refined Analysis DATE: 18/04/04 13:51:34 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB) and S.J. LaPorte report on behalf of the Swift-XRT team: We have analysed 8.4 ks of XRT data for GRB 180404B (LaPorte et al. GCN Circ. 22590), from 63 s to 30.6 ks after the BAT trigger. The data comprise 349 s in Windowed Timing (WT) mode (the first 5 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. 22594). The late-time light curve (from T0+5.2 ks) can be modelled with a power-law decay with a decay index of alpha=1.52 (+0.14, -0.13). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.61 (+/-0.04). The best-fitting absorption column is 3.00 (+0.25, -0.23) x 10^21 cm^-2, in excess of the Galactic value of 1.1 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.06 (+/-0.14) and a best-fitting absorption column of 4.2 (+/-0.7) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (6.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.2 (+/-0.7) x 10^21 cm^-2 Galactic foreground: 1.1 x 10^20 cm^-2 Excess significance: 10.0 sigma Photon index: 2.06 (+/-0.14) If the light curve continues to decay with a power-law decay index of 1.52, the count rate at T+24 hours will be 4.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x 10^-13 (2.8 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/00821902. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22599 SUBJECT: GRB 180404A: Swift-BAT refined analysis DATE: 18/04/04 14:33:36 GMT FROM: Takanori Sakamoto at AGU S. D. Barthelmy (GSFC), J. R. Cummings (CPI), J. D. Gropp (PSU), H. A. Krimm (NSF/USRA), 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+654 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180404A (trigger #821881) (Gropp, et al., GCN Circ. 22589). The BAT ground-calculated position is RA, Dec = 83.540, -37.168 deg which is RA(J2000) = 05h 34m 09.5s Dec(J2000) = -37d 10' 05.0" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 82%. The mask-weighted light curve shows a weak emission that starts at T-25 sec, followed by a bright peak which peaks at T+3 sec and ends at T+30 sec. T90 (15-350 keV) is 35.2 +- 5.3 sec (estimated error including systematics). The time-averaged spectrum from T-20.7 to T+24.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.95 +- 0.12. The fluence in the 15-150 keV band is 1.3 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+1.99 sec in the 15-150 keV band is 1.3 +- 0.2 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/821881/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22601 SUBJECT: GRB 180404B: Swift-BAT refined analysis DATE: 18/04/04 20:39:26 GMT FROM: Amy Lien at GSFC J. R. Cummings (CPI), S. D. Barthelmy (GSFC), H. A. Krimm (NSF/USRA), S. J. LaPorte (PSU), 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-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180404B (trigger #821902) (LaPorte et al., GCN Circ. 22590). The BAT ground-calculated position is RA, Dec = 53.390, -50.213 deg which is RA(J2000) = 03h 33m 33.6s Dec(J2000) = -50d 12' 47.4" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 84%. The mask-weighted light curve shows a major pulse that starts at ~ T-6 s and peaks at ~ T+ 10 s. Another weaker pulse arises at the end of the major pulse at ~ T+40 s. The second pulse peaks at ~ T+50 s and lasts until ~ T+200 s. T90 (15-350 keV) is 111.5 +- 7.1 sec (estimated error including systematics). The time-averaged spectrum from T-5.91 to T+195.64 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.35 +- 0.04. The fluence in the 15-150 keV band is 1.20 +- 0.02 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+8.88 sec in the 15-150 keV band is 5.2 +- 0.2 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/821902/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22602 SUBJECT: GRB 180404A: Swift-XRT refined Analysis DATE: 18/04/05 00:55:03 GMT FROM: Phil Evans at U of Leicester A. Tohuvavohu (PSU), S. J. LaPorte (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), J.A. Kennea (PSU) and J.D. Gropp report on behalf of the Swift-XRT team: We have analysed 3.9 ks of XRT data for GRB 180404A (Gropp et al. GCN Circ. 22589), from 90 s to 52.0 ks after the BAT trigger. The data comprise 26 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 22592). The light curve can be modelled with a power-law decay with a decay index of alpha=0.5 (+nan, -nan). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.62 (+0.27, -0.22). The best-fitting absorption column is consistent with the Galactic value of 3.1 x 10^20 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 (4.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.1 (+/-5.1) x 10^20 cm^-2 Galactic foreground: 3.1 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.62 (+0.27, -0.22) If the light curve continues to decay with a power-law decay index of 0.5, the count rate at T+24 hours will be 0.011 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x 10^-13 (4.5 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/00821881. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22603 SUBJECT: GRB 180404A: LCO FTS observations DATE: 18/04/05 09:36:04 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi, R. Martone (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU) on behalf of a large collaboration report: We began observing Swift GRB180404A (Gropp et al. GCN 22589) on April 4, 09:30 UT (0.36 days post burst) with the LCO 2-m Faulkes Telescope South unit in Siding Springs in the SDSS-R filter. We marginally detect the optical afterglow (Gropp et al.; Selsing et al. GCN 22591) with the following magnitude: Mid time since GRB     Exp        Filter         Magnitude (days)                 (s) ------------------------------------------------------------- 0.37                   5x120      SDSS-R         21.3 +- 0.3 ------------------------------------------------------------- as calibrated against nearby USNO UCAC4 objects. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22605 SUBJECT: GRB 180404A: Swift/UVOT Detection DATE: 18/04/05 17:04:53 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and J. D. Gropp (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 180404A 90 s after the BAT trigger (Gropp et al., GCN Circ. 22589). A source consistent with the XRT position (Osborne et al. GCN Circ. 22592) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 05:34:11.64 = 83.54850 (deg.) Dec (J2000) = -37:10:03.9 = -37.16774 (deg.) with an estimated uncertainty of 0.50 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) 90 240 147 19.47 +/- 0.09 white 90 770 180 19.34 +/ -0.10 white 45830 52026 1028 >21.66 v 632 5179 99 >18.9 b 558 750 39 >19.4 u (fc) 302 552 246 18.95 +/- 0.12 u 303 726 265 18.95 +/ -0.14 w1 682 701 19 >17.8 m2 656 676 19 >17.4 w2 607 5094 216 19.45 +/- 0.28 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22607 SUBJECT: GRB 180404C CALET Gamma-Ray Burst Monitor detection DATE: 18/04/06 01:23:16 GMT FROM: Takanori Sakamoto at AGU P. S. Marrocchesi (U of Siena), A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo, A. Tezuka, S. Matsukawa (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, and the CALET collaboration: The long-duration, hard-spectrum, bright GRB 180404C triggered the CALET Gamma-ray Burst Monitor (CGBM) at 21:42:08.587 UTC on 4 April 2018. The burst signal was seen by all CGBM detectors. This GRB is also clearly seen by the publicly available INTEGRAL SPI-ACS light curve. The burst light curve shows a single pulse which starts at T+1.7 sec, peaks at T+5.5 sec and ends at T+34.1 sec. The T90 and the T50 durations measured by the SGM data are 25.4 +- 3.1 sec and 9.5 +- 1.4 sec (40-1000 keV), respectively. CGBM HV was turned off at ~T+65 sec due to entering the radiation belts, so no CGBM data are available from that time until ~T+1000 sec. The ground processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1206913306/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22609 SUBJECT: Konus-Wind observation of GRB 180404B DATE: 18/04/06 13:33:29 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 180404B (Swift-BAT detection: LaPorte et al., GCN Circ. 22590; Fermi-GBM observation: von Kienlin, GCN Circ. 22597) triggered Konus-Wind at T0=7898.049 s UT (02:11:38.049). The burst light curve shows the bright pulse which starts at ~T0-3.4 s and has a total duration of ~29 s followed by a weaker pulse seen up to ~T0+100 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180404_T07898/ As observed by Konus-Wind, the burst had a fluence of 2.60(-0.16,+0.18)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+8.832 s, of 2.07(-0.66,+0.66)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+73.984 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 = -0.65(-0.15,+0.16) and Ep = 205(-17,+21) keV (chi2 = 82/73 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.0 (chi2 = 82/72 dof). The spectrum near the maximum count rate (measured from T0+8.448 to T0+16.640 s) is best fit in the 20 keV - 5 MeV range by a power law with exponential cutoff model: with alpha = -0.19(-0.16,+0.17) and Ep = 186(-11,+12) keV (chi2 = 90/73 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.2 (chi2 = 90/72 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22610 SUBJECT: IPN Triangulation of GRB 180404C (long) DATE: 18/04/06 18:02:49 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, A. Ursi, N. Parmiggiani, F. Verrecchia, A. Bulgarelli, A. Trois, M. Marisaldi, C. Pittori, M. Tavani, Y. Evangelista, I. Donnarumma, M. Cardillo, G. Piano, G. Minervini, A. Argan, F. Lucarelli, A. Zoli, V. Fioretti, F. Fuschino, M. Pilia, F. Longo, A. Giuliani on behalf of the AGILE team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The long-duration GRB 180404C (Marrocchesi et al., GCN Circ. 22607) was detected by Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), CALET (CGBM), and AGILE (MCAL) at about 78128 s UT (21:42:08). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 92.302 (06h 09m 13s) +7.811 ( +7d 48' 38") Corners: 94.505 (06h 18m 01s) +6.262 ( +6d 15' 44") 90.162 (06h 00m 39s) +8.179 ( +8d 10' 43") 90.059 (06h 00m 14s) +9.822 ( +9d 49' 21") 94.425 (06h 17m 42s) +7.688 ( +7d 41' 17") --------------------------------------------- The error box area is 6.37 sq. deg, and its maximum dimension is 5.66 deg (the minimum one is 80 arcmin). The Sun distance was 75 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB180404_T78131/IPN The Konus-Wind time history and spectrum will be given a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22611 SUBJECT: GRB 180404B: Swift/UVOT Detection DATE: 18/04/06 18:14:06 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and S. J. LaPorte (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 180404B 82 s after the BAT trigger (LaPorte et al., GCN Circ. 22590). A fading source consistent with the XRT position (Beardmore et al. GCN Circ. 22594) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 03:33:34.23 = 53.39262 (deg.) Dec (J2000) = -50:12:54.2 = -50.21506 (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) 82 231 147 18.66 +/- 0.09 white 82 1720 411 19.39 +/- 0.09 white 6421 6620 196 >20.7 v 624 7031 510 >19.5 b 550 7661 322 >20.3 u (fc) 295 545 245 19.49 +/- 0.31 u 295 1670 343 19.70 +/- 0.29 u 6011 7648 393 >20.1 w1 674 7442 510 >20.6 m2 1600 7236 413 >20.5 w2 600 6826 452 >20.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22624 SUBJECT: Konus-Wind observation of GRB 180404C DATE: 18/04/10 14:05:04 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 180404C (CATET-GBM detection: Marrocchesi et al., GCN Circ. 22607; IPN triangulation: Hurley et al., GCN Circ. 22610) triggered Konus-Wind at T0=78131.929 s UT (21:42:11.929). The burst light curve shows a multi-peaked structure which starts at ~T0-88 s and has a total duration of ~200 s. The emission is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180404_T78131/ As observed by Konus-Wind, the burst had a fluence of 1.33(-0.18,+0.19)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+2.672 s, of 2.11(-0.37,+0.37)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+116.736 s) is best fit in the 20 keV - 19 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.00(-0.10,+0.12), the high energy photon index beta = -2.40(-0.56,+0.24), the peak energy Ep = 342(-49,+58) keV (chi2 = 91/97 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+4.864 s) is best fit in the 20 keV - 19 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.58(-0.11,+0.13), the high energy photon index beta = -2.00(-0.12,+0.09), the peak energy Ep = 517(-71,+86) keV (chi2 = 86/94 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22645 SUBJECT: GRB 180404B: AstroSat CZTI detection DATE: 18/04/16 17:52:13 GMT FROM: Vidushi Sharma at IUCAA V. Sharma (IUCAA), V. Bhalerao (IIT-B), 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 the detection of a long GRB 180404B, which was also detected by Swift (Palmer D. et al., GCN 22590), Fermi-GBM (Kienlin A. V. et al., GCN 22597) and Konus-Wind (Svinkin D. et al., GCN 22609). The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 02:11:53.5 UT, ~9.5 s after the Swift trigger. The measured peak count rate is 281.6 cts/s above the background in combined data of four quadrants, with a total of 3662 cts. The local mean background count rate was 541 cts/s. Using cumulative rates, we measure a T90 of 44 s. It was also clearly detected in the CsI anticoincidence (Veto) detector 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.