Gamma-ray Burst 190804B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Notice
  

  TITLE:           GCN/MAXI NOTICE
  NOTICE_DATE:     Sun 04 Aug 19 11:31:10 UT
  NOTICE_TYPE:     MAXI Unknown Source Position
  EVENT_ID_NUM:    699271870
  EVENT_RA:        239.44d {+15h 57m 45s} (J2000),
                   239.78d {+15h 59m 07s} (current),
                   238.56d {+15h 54m 15s} (1950)
  EVENT_DEC:       -44.39d {-44d 23' 12"} (J2000),
                   -44.44d {-44d 26' 31"} (current),
                   -44.24d {-44d 14' 36"} (1950)
  EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
  EVENT_FLUX:      100.0 +- 0.0 [mCrab]
  EVENT_DATE:      18699 TJD;   216 DOY;   19/08/04
  EVENT_TIME:      28695.00 SOD {07:58:15.00} UT
  EVENT_TSCALE:    1s
  EVENT_EBAND:     Low, 2-4 keV
  SUN_POSTN:       134.28d {+08h 57m 08s}  +17.24d {+17d 14' 28"}
  SUN_DIST:        112.94 [deg] 
  MOON_POSTN:      180.79d {+12h 03m 10s}   +4.98d {+04d 59' 05"}
  MOON_DIST:        72.20 [deg] 
  MOON_ILLUM:      16 [%] 
  GAL_COORDS:      334.45,  6.79 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      246.68,-23.39 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.
  

• GCN Circular #25262
  T. Sato (Chuo U.), H. Negoro, M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai (Chuo U.), M. Shidatsu (Ehime U.), N. Kawai, M. Sugizaki, M. Oeda, K. Shiraishi (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, N.Isobe, R. Shimomukai, M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, Y. Kurihara, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU) report on behalf of the MAXI team:
  The MAXI/GSC nova alert system triggered on an uncatalogued X-ray transient source at 07:58:15 UT on 2019 August 04. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (239.895 deg, -44.773 deg) = (15 59 34, -44 46 22) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.29 deg and 0.24 deg, respectively. The roll angle of the long axis from the north direction is 39.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 118 +- 21 mCrab (4.0-10.0keV, 1 sigma error).
  Without assumptions on the source constancy,we obtain a rectangular error box for the transient source with the following corners:

  (R.A., Dec) = (240.071, -43.705) deg = (16 00 17, -43 42 17) (J2000)
  (R.A., Dec) = (239.431, -43.730) deg = (15 57 43, -43 43 47) (J2000)
  (R.A., Dec) = (239.594, -45.994) deg = (15 58 22, -45 59 38) (J2000)
  (R.A., Dec) = (240.259, -45.968) deg = (16 01 02, -45 58 04) (J2000)
  

  There was no significant excess flux in the previous transit at 06:25 UT, and in the next transit at 09:30 UT with an upper limit of 20 mCrab for each.
• GCN Circular #25263
  P. A. Evans (U. Leicester) reports on behalf of the Swift team:
  Swift has initiated a series of observations, tiled on the sky, of the MAXI GRB 190804B. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00082
  Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the MAXI event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration.
  Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
  This circular is an official product of the Swift-XRT team.
• GCN Circular #25267
  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 (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) started inspect of the MAXI GRB190804.33 (trigger No 6992871870, 15h 57m 44.64s , -44d 23m 13.20s, R=1) errorbox 32405 sec after trigger time at 2019-08-04 16:58:20 UT, with upper limit up to 19.5 mag. Observations started at twilight. The observations began at zenit distance = 14 deg. The sun altitude is -11.8 deg.
  MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) started inspect of the MAXI GRB190804.33 errorbox 45665 sec after trigger time at 2019-08-04 20:39:20 UT, with upper limit up to 16.4 mag. Observations started at twilight. The observations began at zenit distance = 72 deg. The sun altitude is -10.7 deg.
  The galactic latitude b = -60 deg., longitude l = 98 deg.
  Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1095913
  We obtain a following upper limits.

  Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)|Filt.| Expt. | Limit| Comment
  _________|_____________________|_____________________|____________________________________|__|_______|_______|________
  
     32436 | 2019-08-04 16:58:20 |         MASTER-SAAO | ( 15h 52m 08.48s , -43d 54m 03.18s) |C |    60 | 18.2 | 
     32592 | 2019-08-04 16:59:56 |         MASTER-SAAO | ( 15h 57m 42.32s , -44d 17m 23.77s) |C |   180 | 19.1 |
     32755 | 2019-08-04 17:03:39 |         MASTER-SAAO | ( 15h 50m 50.95s , -43d 54m 24.34s) |C |    60 | 18.5 |
     32851 | 2019-08-04 17:05:15 |         MASTER-SAAO | ( 16h  1m 58.45s , -43d 54m 38.91s) |C |    60 | 18.8 |
     33008 | 2019-08-04 17:06:52 |         MASTER-SAAO | ( 16h  2m 51.67s , -44d 16m 44.63s) |C |   180 | 19.5 |
     33167 | 2019-08-04 17:10:31 |         MASTER-SAAO | ( 16h  3m 07.03s , -43d 54m 23.19s) |C |    60 | 18.9 |
     45696 | 2019-08-04 20:39:20 |          MASTER-IAC | ( 16h  0m 30.33s , -43d 56m 36.85s) |C |    60 | 16.4 |
  

  Filter C is a clear (unfiltred) band.
  The observation and reduction will continue. The message may be cited.
• GCN Circular #25273
  J.P. Osborne (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (ASDC), V. D'Elia (ASDC), A. Tohuvavohu (PSU), J.A. Kennea (PSU), B. Sbarufatti (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
  Swift-XRT has performed follow-up observations of the MAXI-detected burst GRB 190804B (Sato et al. GCN Circ. 25262) in a series of observations tiled on the sky. The total exposure time is 1.3 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 395 s. The data were collected between T0+37.2 ks and T0+38.6 ks, and are entirely in Photon Counting (PC) mode.
  Two uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below:
  Source 1:

    RA (J2000.0):  239.7568  =  15:59:1.62
    Dec (J2000.0): -44.6361  =  -44:38:09.8
    Error: 4.1 arcsec (radius, 90% conf. [Enhanced position])
    Count-rate: 0.031 [+0.014, -0.011] ct s^-1
    Distance: 606 arcsec from MAXI position.  
    Flux: (1.38 [+0.60, -0.46])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)
  

  Source 2:

    RA (J2000.0):  240.0251  =  16:00:6.02
    Dec (J2000.0): -44.7816  =  -44:46:53.9
    Error: 3.9 arcsec (radius, 90% conf. [Enhanced position])
    Count-rate: 0.113 [+0.038, -0.031] ct s^-1 
    Distance: 333 arcsec from MAXI position.
    Flux: (5.1 [+1.7, -1.4])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)
  

  The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00082.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #25286
  J.P. Osborne (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (ASDC), V. D'Elia (ASDC), A. Tohuvavohu (PSU), J.A. Kennea (PSU), B. Sbarufatti (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
  Swift-XRT has conducted further observations of the field of the MAXI-detected burst GRB 190804B (Sato et al. GCN Circ. 25262). The observations now extend from T0+37.2 ks to T0+273.4 ks.
  Of the sources reported by Osborne et al. (GCN Circ. 25273), "Source 2" has faded from 1.1e-01 count/s to 1.1e-03 count/s between observations and is believed to be the afterglow. The position of this source (astrometrically enhanced by using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec=240.0251, -44.7816 which is equivalent to:

  RA (J2000): 16:00:6.02
  Dec(J2000): -44:46:53.9
  

  with an uncertainty of 3.8 arcsec (radius, 90% confidence). Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 177). This position is 5.6 arcmin from the MAXI position.
  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020916. The results of the full analysis of the tiled XRT observations are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00082.
  This circular is an official product of the Swift-XRT team.