Gamma-ray Burst 200517A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Notice
  

  TITLE:           GCN/MAXI NOTICE
  NOTICE_DATE:     Sun 17 May 20 11:49:35 UT
  NOTICE_TYPE:     MAXI Unknown Source Position
  EVENT_ID_NUM:    986397145
  EVENT_RA:         17.23d {+01h 08m 55s} (J2000),
                    17.45d {+01h 09m 48s} (current),
                    16.69d {+01h 06m 45s} (1950)
  EVENT_DEC:       -50.74d {-50d 44' 41"} (J2000),
                   -50.64d {-50d 38' 11"} (current),
                   -51.01d {-51d 00' 39"} (1950)
  EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
  EVENT_FLUX:      198.0 +- 0.0 [mCrab]
  EVENT_DATE:      18986 TJD;   138 DOY;   20/05/17
  EVENT_TIME:      41245.00 SOD {11:27:25.00} UT
  EVENT_TSCALE:    1s
  EVENT_EBAND:     Low, 2-4 keV
  SUN_POSTN:        54.75d {+03h 38m 59s}  +19.49d {+19d 29' 36"}
  SUN_DIST:         77.43 [deg] 
  MOON_POSTN:        1.20d {+00h 04m 47s}   -5.15d {-05d 08' 45"}
  MOON_DIST:        47.49 [deg] 
  MOON_ILLUM:      24 [%] 
  GAL_COORDS:      296.08,-66.15 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      347.31,-51.72 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.
  

• GCN Circular #27750
  M. Niwano (Tokyo Tech), H. Negoro (Nihon U.), M. Serino (AGU), M. Nakajima, M. Aoki, K. Kobayashi, R. Takagi, K, Asakura, K, Seino, S. Mokumoto (Nihon U.), T. Mihara, C. Guo, Y. Zhou, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.), M. Shidatsu (Ehime U.), N. Kawai, R. Adachi (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA), Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi (Osaka U.), M. Yamauchi, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC) report on behalf of the MAXI team:
  The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 11:27:21 UT . We obtained the source position at
  (R.A., Dec) = (17.230 deg, -50.745 deg) = (01 08 55, -50 44 41) (J2000)
  with a rectangular error box with the following corners:

  (15.411, -49.816) deg = (01 01 38, -49 48 57) (J2000)
  (15.002, -50.346) deg = (01 00 00, -50 20 45) (J2000)
  (18.572, -51.401) deg = (01 14 17, -51 24 03) (J2000)
  (18.949, -50.859) deg = (01 15 47, -50 51 32) (J2000)
  

  There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 198 +- 33 mCrab (4.0-10.0keV, 1 sigma error). There was no significant excess flux in the previous transit at 09:54 UT with an upper limit of 20 mCrab.
• GCN Circular #27751
  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 200517A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00090
  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 #27754
  B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), J. D. Gropp (PSU) 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 200517A (Niwano et al. GCN Circ. 27750) in a series of observations tiled on the sky. The total exposure time is 1.1 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 388 s. The data were collected between T0+8.0 ks and T0+8.3 ks, and are entirely in Photon Counting (PC) mode.
  An uncatalogued X-ray source is detected and is above the RASS limit, and is therefore likely the GRB afterglow. Using 366 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 17.69837, -50.92242 which is equivalent to:

  RA (J2000): 01h 10m 47.61s
  Dec(J2000): -50d 55' 20.7"
  

  with an uncertainty of 3.3 arcsec (radius, 90% confidence). This position is 20.7 arcmin from the MAXI position. We cannot determine at the present time whether the source is fading.
  The results of the XRT-team automatic analysis of the likely afterglow are at https://www.swift.ac.uk/xrt_products/TILED_GRB00090/Source1.php. The results of the full analysis of the tiled XRT observations are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00090.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #27758
  C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team:
  MAXI/GSC detected GRB 200517A at 11:27:21 UT (GCN 27750). There was no Fermi-GBM onboard trigger around the event.
  An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no counterparts.
  The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals identified a transient most significantly on the 8.192 s timescale, with a log likelihood ratio of 13 and a location consistent with the MAXI/GSC event. The GBM targeted search event was found with the highest significance with a "soft" spectrum (Band function with Epeak=70 keV, alpha=-1.9, beta=-3.7) for a GRB.
  [1] Goldstein et al. 2019 arXiv:1903.12597
• GCN Circular #27775
  J. Gropp (PSU) reports on behalf of the Swift-XRT team:
  We provide an update on the XRT light curve evolution of the candidate X-ray afterglow of GRB 200517A (GCN Circ. 27750).
  The XRT light curve now comprises data up to 300 ks from the MAXI trigger (GCN Circs. 27750). There is a firm indication of fading with respect to the first observation as reported previously (GCN Circ 27754), with a decay index of 1.04 (+0.21, -0.18). We thus confirm that this is indeed the afterglow of GRB 200517A. The latest results can be viewed via: https://www.swift.ac.uk/xrt_curves/00020993/
  This circular is an official product of the Swift-XRT team.