//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27535 SUBJECT: GRB 200411A: Fermi GBM Final Real-time Localization DATE: 20/04/11 04:39:27 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely SHORT GRB At 04:29:02 UT on 11 Apr 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200411A (trigger 608272147.522124 / 200411187). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 69.6, Dec = -60.3 (J2000 degrees, equivalent to J2000 04h 38m, -60d 17'), with a statistical uncertainty of 24.1 degrees. The angle from the Fermi LAT boresight is 128.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200411187/quicklook/glg_skymap_all_bn200411187.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200411187/quicklook/glg_healpix_all_bn200411187.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200411187/quicklook/glg_lc_medres34_bn200411187.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27536 SUBJECT: GRB 200411A: Swift detection of a short burst DATE: 20/04/11 04:43:03 GMT FROM: David Palmer at LANL A. Tohuvavohu (U Toronto), S. D. Barthelmy (GSFC), J. A. Kennea (PSU), N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and T. N. Ukwatta (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 04:29:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200411A (trigger=965784). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 47.659, -52.314, which is RA(J2000) = 03h 10m 38s Dec(J2000) = -52d 18' 51" 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 0.5 sec. The peak count rate was ~6000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 04:29:53.0 UT, 50.7 seconds after the BAT trigger. The position determined from promptly downlinked data differs significantly from the on-board position, suggesting that the XRT may have centroided on a cosmic ray; the initial XRT position notice should be treated with caution. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 47.66239, -52.31805 which is equivalent to: RA(J2000) = 03h 10m 38.97s Dec(J2000) = -52d 19' 05.0" with an uncertainty of 3.5 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 https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.55 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.4 (+5.14/-3.83) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of nominal 150.000 seconds with the White filter starting 58 seconds after the BAT trigger. Further analysis is required before any results can be obtained. Burst Advocate for this burst is A. Tohuvavohu (tohuvavohu AT astro.utoronto.ca). 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: 27538 SUBJECT: GRB 200411A: Enhanced Swift-XRT position DATE: 20/04/11 09:33:23 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 980 s of XRT Photon Counting mode data and 2 UVOT images for GRB 200411A, 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 = 47.66418, -52.31764 which is equivalent to: RA (J2000): 03h 10m 39.40s Dec (J2000): -52d 19' 03.5" 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: 27539 SUBJECT: GRB 200411A: Swift/UVOT Upper Limits DATE: 20/04/11 09:55:39 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and A. Tohuvavohu (U. Toronto) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 200411A 58 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 27536). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 27538) 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 58 208 147 >20.8 u_FC 270 520 246 >20.4 white 58 1540 392 >21.2 v 601 1417 97 >18.5 b 525 1343 78 >20.3 u 270 1490 343 >21.0 w1 651 1466 97 >18.8 m2 626 646 19 >18.1 w2 576 1220 58 >19.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27540 SUBJECT: GRB 200411A: Swift-XRT refined Analysis DATE: 20/04/11 10:43:20 GMT FROM: Phil Evans at U of Leicester J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (PSU) and A. Tohuvavohu report on behalf of the Swift-XRT team: We have analysed 6.6 ks of XRT data for GRB 200411A (Tohuvavohu et al. GCN Circ. 27536), from 39 s to 13.0 ks after the BAT trigger. The data comprise 8 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 27538). The light curve can be modelled with a power-law decay with a decay index of alpha=1.16 (+0.11, -0.10). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.74 (+0.25, -0.24). The best-fitting absorption column is 1.3 (+0.9, -0.7) x 10^21 cm^-2, in excess of the Galactic value of 1.6 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 3.9 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.3 (+0.9, -0.7) x 10^21 cm^-2 Galactic foreground: 1.6 x 10^20 cm^-2 Excess significance: 2.6 sigma Photon index: 1.74 (+0.25, -0.24) If the light curve continues to decay with a power-law decay index of 1.16, the count rate at T+24 hours will be 4.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x 10^-14 (2.3 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00965784. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27542 SUBJECT: Swift GRB 200411A: Global MASTER-Net observations report DATE: 20/04/11 17:56:28 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 200411A ( A. Tohuvavohu et al., GCN 27536) errorbox 46681 sec after notice time and 46701 sec after trigger time at 2020-04-11 17:27:24 UT, with upper limit up to 18.9 mag. Observations started at twilight. The observations began at zenith distance = 56 deg. The sun altitude is -14.6 deg. The galactic latitude b = -54 deg., longitude l = 266 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1334193 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 46792 | MASTER-SAAO | C | 180 | 18.9 | 46794 | MASTER-SAAO | C | 180 | 18.9 | 47360 | MASTER-SAAO | C | 180 | 17.8 | 47363 | MASTER-SAAO | C | 180 | 17.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27543 SUBJECT: GRB 200411A: Fermi GBM observation DATE: 20/04/11 20:18:43 GMT FROM: Joshua Wood at MSFC/Fermi-GBM E. Bissaldi (Politecnico and INFN Bari), C. Meegan (UAH), and J. Wood (NASA/MSFC) report on behalf of the Fermi GBM Team: "At 04:29:02.52 UT on 11 April 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 200411A (trigger 608272147 / 200411187), which was also detected by the Swift/BAT (Tohuvavohu et al. 2020, GCN 27536) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 116 degrees. The GBM light curve shows a single pulse with a duration (T90) of about 1.4 s (50-300 keV). The time-averaged spectrum from T0-0.064 s to T0+0.192 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -0.64 +/- 0.22 and the cutoff energy, parameterized as Epeak, is 420 +/- 120 keV. The event fluence (10-1000 keV) in this time interval is (4.7 +/- 0.6)E-07 erg/cm^2. The 64-ms peak photon flux measured starting from T0-0.064 s in the 10-1000 keV band is 11.9 +/- 1.5 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27545 SUBJECT: GRB 200411A: Swift-BAT refined analysis DATE: 20/04/12 03:24:25 GMT FROM: Amy Lien at GSFC H. A. Krimm (NSF), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), A. Tohuvavohu (U Toronto), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-239 to T+880 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200411A (trigger #965784) (Tohuvavohu et al., GCN Circ. 27536). The BAT ground-calculated position is RA, Dec = 47.686, -52.320 deg which is RA(J2000) = 03h 10m 44.7s Dec(J2000) = -52d 19' 12.6" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a couple overlapping pulses that starts at ~T-0.02 s and ends at ~T+0.25 s. The highest peak occurs at ~ T+0.05 s. T90 (15-350 keV) is 0.22 +- 0.04 sec (estimated error including systematics). The time-averaged spectrum from T-0.02 to T+0.25 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.95 +- 0.19. The fluence in the 15-150 keV band is 8.6 +- 1.1 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T-0.38 sec in the 15-150 keV band is 1.1 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Using the 4-ms binned light curve, the spectral lag of the short pulse is 1 (+7, -4) ms for the 100-350 keV to 25-50 keV bands, and 8 (+6, -6) ms for the 50-100 keV to 15-25 keV bands. These values are more consistent with those of short GRBs. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/965784/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27573 SUBJECT: GRB 200411A: ATCA 5/9 GHz radio observations DATE: 20/04/14 09:58:55 GMT FROM: Gemma Anderson at Curtin U G. E. Anderson (Curtin), M. E. Bell (UTS), J. Stevens (CASS), P. J. Hancock (Curtin), J. C. A. Miller-Jones (Curtin), M. D. Aksulu (UvA), A. Bahramian (Curtin), K. W. Bannister (CASS), A. J. van der Horst (GWU), S. D. Ryder (Macquarie), J-P. Macquart (Curtin), R. M. Plotkin (UNR), A. Rowlinson (UvA), R. A. M. J. Wijers (UvA) We used the Australia Telescope Compact Array (ATCA) to perform a radio observation of the short GRB 200411A. The rapidly scheduled observations began on 2020 Apr 11.25 UT for 5 hours (1.5 hrs post-burst; Fermi GBM Team GCN 27535, A. Tohuvavohu et al., GCN 27536). No radio source was detected at the enhanced Swift-XRT position (J.P. Osborne et al., GCN 27538), with preliminary 3 sigma upper-limits of 45 microJy and 36 microJy at 5.5 and 9 GHz, respectively. Further observations are planned. We thank the ATCA and CSIRO Astronomy and Space Science (CASS) staff for scheduling these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27589 SUBJECT: GRB 200411A: Chandra observations indicative of temporal steepening DATE: 20/04/15 21:20:48 GMT FROM: Wen-fai Fong at Northwestern U A. Rouco Escorial, W. Fong (Northwestern), and E. Berger (Harvard) report: “We initiated observations with the Chandra X-ray Observatory of the position of the short-duration GRB 200411A (Fermi-GBM et al., GCN 27535; Tohuvavohu et al., GCN 27536; Bissaldi et al., GCN 27543) starting on 2020 April 15 00:16:54 UT, or at a mid-time of 3.95 days after the GRB trigger. ACIS-S observations were taken under Proposal 21500089 (ObsID 22427; PI: Berger), with a total exposure time of 19.8 ksec. We do not detect an X-ray source within or around the enhanced Swift-XRT position (90% confidence; Osborne et al., GCN 27538). Centered on the XRT position, we calculate a 3-sigma limit of <4.5e-4 cts/s in the 0.5-8 keV energy range following the method described by Gehrels (1986) for small numbers of events. Applying the best-fit PC mode XRT spectral parameters (Gamma=1.7, intrinsic NH=1.5e21 cm^-2) and fixing the Galactic NH=1.55e20 cm^-2 (Willingale et al. 2013), we calculate a 3-sigma unabsorbed flux limit of FX<8.4e-15 erg/s/cm^2 in the 0.3-10 keV energy range. The XRT afterglow starting from 200 sec post-burst exhibits a power-law decline with decay index alpha=-0.84 (+/- 0.2) (where FX~t^alpha), while the Chandra upper limit indicates a potential steepening to alpha<-1.3. If this steepening is interpreted as a jet break at ~0.5-2 days post-burst, using median values for the explosion properties and redshift based on properties of short GRBs gives an opening angle of ~4-7 degrees. We thank the Chandra staff for the rapid planning and scheduling of these observations.”