Gamma-ray Burst 170522A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 22 May 17 15:45:59 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      48
TRIGGER_NUM:     517160740
GRB_RA:          136.167d {+09h 04m 40s} (J2000),
                 136.423d {+09h 05m 42s} (current),
                 135.428d {+09h 01m 43s} (1950)
GRB_DEC:         +26.633d {+26d 37' 60"} (J2000),
                 +26.563d {+26d 33' 48"} (current),
                 +26.833d {+26d 49' 58"} (1950)
GRB_ERROR:       5.53 [deg radius, statistical plus systematic]
GRB_INTEN:       570 [cnts/sec]
DATA_SIGNIF:     29.00 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        17895 TJD;   142 DOY;   17/05/22
GRB_TIME:        56735.28 SOD {15:45:35.28} UT
GRB_PHI:          65.00 [deg]
GRB_THETA:        50.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.26
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       0,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        59.64d {+03h 58m 33s}  +20.51d {+20d 30' 27"}
SUN_DIST:         69.63 [deg]   Sun_angle= -5.1 [hr] (East of Sun)
MOON_POSTN:       17.53d {+01h 10m 07s}   +3.30d {+03d 17' 52"}
MOON_DIST:       113.94 [deg]
MOON_ILLUM:      14 [%]
GAL_COORDS:      199.74, 39.89 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      130.83,  9.50 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170522657/quicklook/glg_lc_medres34_bn170522657.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 103.80,18.27 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 22 May 17 15:46:09 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      60
TRIGGER_NUM:     517160740
GRB_RA:          138.917d {+09h 15m 40s} (J2000),
                 139.178d {+09h 16m 43s} (current),
                 138.164d {+09h 12m 39s} (1950)
GRB_DEC:         +31.150d {+31d 08' 60"} (J2000),
                 +31.077d {+31d 04' 37"} (current),
                 +31.359d {+31d 21' 31"} (1950)
GRB_ERROR:       3.88 [deg radius, statistical plus systematic]
GRB_INTEN:       1652 [cnts/sec]
DATA_SIGNIF:     122.40 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        17895 TJD;   142 DOY;   17/05/22
GRB_TIME:        56735.28 SOD {15:45:35.28} UT
GRB_PHI:          65.00 [deg]
GRB_THETA:        45.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.39
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   3%  Generic Transient
DETECTORS:       0,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        59.64d {+03h 58m 33s}  +20.51d {+20d 30' 27"}
SUN_DIST:         70.95 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
MOON_POSTN:       17.53d {+01h 10m 07s}   +3.30d {+03d 17' 54"}
MOON_DIST:       114.77 [deg]
MOON_ILLUM:      14 [%]
GAL_COORDS:      194.49, 43.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      131.79, 14.53 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170522657/quicklook/glg_lc_medres34_bn170522657.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 103.80,18.27 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 22 May 17 15:46:12 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     517160740
GRB_RA:          135.680d {+09h 02m 43s} (J2000),
                 135.935d {+09h 03m 44s} (current),
                 134.944d {+08h 59m 47s} (1950)
GRB_DEC:         +25.830d {+25d 49' 48"} (J2000),
                 +25.761d {+25d 45' 38"} (current),
                 +26.028d {+26d 01' 41"} (1950)
GRB_ERROR:       1.28 [deg radius, statistical only]
DATA_SIGNIF:     99.40 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        17895 TJD;   142 DOY;   17/05/22
GRB_TIME:        56735.28 SOD {15:45:35.28} UT
GRB_PHI:          65.00 [deg]
GRB_THETA:        51.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:        59.64d {+03h 58m 33s}  +20.51d {+20d 30' 27"}
SUN_DIST:         69.39 [deg]   Sun_angle= -5.1 [hr] (East of Sun)
MOON_POSTN:       17.53d {+01h 10m 08s}   +3.30d {+03d 17' 55"}
MOON_DIST:       113.75 [deg]
MOON_ILLUM:      14 [%]
GAL_COORDS:      200.60, 39.26 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      130.64,  8.60 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170522657/quicklook/glg_lc_medres34_bn170522657.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_517160740.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        Bright hard burst in the GBM.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 22 May 17 15:47:08 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      3
TRIGGER_NUM:     517160740
GRB_RA:          135.420d {+09h 01m 41s} (J2000),
                 135.677d {+09h 02m 43s} (current),
                 134.679d {+08h 58m 43s} (1950)
GRB_DEC:         +27.040d {+27d 02' 24"} (J2000),
                 +26.971d {+26d 58' 15"} (current),
                 +27.237d {+27d 14' 13"} (1950)
GRB_ERROR:       1.26 [deg radius, statistical only]
DATA_SIGNIF:     121.30 [sigma]
DATA_INTERVAL:   5.120 [sec]
GRB_DATE:        17895 TJD;   142 DOY;   17/05/22
GRB_TIME:        56735.28 SOD {15:45:35.28} UT
GRB_PHI:          64.00 [deg]
GRB_THETA:        50.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:        59.64d {+03h 58m 33s}  +20.51d {+20d 30' 28"}
SUN_DIST:         68.88 [deg]   Sun_angle= -5.1 [hr] (East of Sun)
MOON_POSTN:       17.54d {+01h 10m 10s}   +3.30d {+03d 18' 06"}
MOON_DIST:       113.17 [deg]
MOON_ILLUM:      14 [%]
GAL_COORDS:      199.01, 39.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      130.06,  9.70 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170522657/quicklook/glg_lc_medres34_bn170522657.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_517160740.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 22 May 17 15:47:27 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      4
TRIGGER_NUM:     517160740
GRB_RA:          135.470d {+09h 01m 53s} (J2000),
                 135.728d {+09h 02m 55s} (current),
                 134.728d {+08h 58m 55s} (1950)
GRB_DEC:         +27.170d {+27d 10' 12"} (J2000),
                 +27.101d {+27d 06' 03"} (current),
                 +27.367d {+27d 22' 02"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
DATA_SIGNIF:     119.10 [sigma]
DATA_INTERVAL:   12.288 [sec]
GRB_DATE:        17895 TJD;   142 DOY;   17/05/22
GRB_TIME:        56735.28 SOD {15:45:35.28} UT
GRB_PHI:          64.00 [deg]
GRB_THETA:        50.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:        59.64d {+03h 58m 33s}  +20.51d {+20d 30' 28"}
SUN_DIST:         68.90 [deg]   Sun_angle= -5.1 [hr] (East of Sun)
MOON_POSTN:       17.54d {+01h 10m 10s}   +3.30d {+03d 18' 10"}
MOON_DIST:       113.17 [deg]
MOON_ILLUM:      14 [%]
GAL_COORDS:      198.87, 39.41 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      130.07,  9.83 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170522657/quicklook/glg_lc_medres34_bn170522657.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_517160740.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 23 May 17 01:26:28 UT
NOTICE_TYPE:     Fermi-LAT Offline Position
TRIGGER_NUM:     517160740     
GRB_RA:          139.340d {+09h 17m 22s} (J2000),
                 139.593d {+09h 18m 22s} (current),
                 138.611d {+09h 14m 27s} (1950)
GRB_DEC:         +25.670d {+25d 40' 12"} (J2000),
                 +25.596d {+25d 35' 47"} (current),
                 +25.880d {+25d 52' 48"} (1950)
GRB_ERROR:       11.40 [arcmin radius, 90% containment, statistical only]  
GRB_DATE:        17895 TJD;   142 DOY;   17/05/22
GRB_TIME:        56735.27 SOD {15:45:35.27} UT
TRIGGER_ID:      0x0
MISC:            0x40000000
SUN_POSTN:        60.04d {+04h 00m 10s}  +20.58d {+20d 35' 06"}
SUN_DIST:         72.24 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
MOON_POSTN:       23.08d {+01h 32m 20s}   +5.21d {+05d 12' 33"}
MOON_DIST:       111.20 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      201.91, 42.41 [deg] galactic lon,lat of the burst (or transient)      
ECL_COORDS:      133.87,  9.43 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi LAT Offline position.
COMMENTS:        This Notice was ground-generated -- not flight-generated.
COMMENTS:        It is the result of human-in-the-loop processing.
COMMENTS:        This is a human generated position of a LAT ground detection.
COMMENTS:        This source corresponds to GBM trigger.

GCN Circular #21126
M. Stanbro and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 15:45:35.28 UT on 22 May 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170522A (trigger 517160740 / 170522657). The on-ground calculated location, using the GBM trigger data, is RA = 135.45, DEC = 27.12, with an uncertainty of 1.0 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).
The trigger resulted in an Autonomous Repoint Request (ARR) by the GBM Flight Software owing to the high peak flux of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight location. The initial angle from the Fermi LAT boresight to the GBM ground location is 50 degrees.
The GBM light curve consists of 1 peak with a duration (T90) of about 7 s (50-300 keV). The time-averaged spectrum from T0-0.00 s to T0+8.32 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.41 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 344 +/- 8 keV.
The event fluence (10-1000 keV) in this time interval is (2.31 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+3.58 s in the 10-1000 keV band is 23.35 +/- 0.37 ph/s/cm^2.
A Band function fits the spectrum equally well with Epeak= 314 +/- 11 keV, alpha = -0.36 +/- 0.03 and beta = -2.63 +/- 0.15.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #21127
M. Arimoto (Waseda University) and J. L. Racusin (NASA/GSFC) report on behalf of the Fermi-LAT team:
At 15:45:35.28 on May, 22, 2017 Fermi-LAT detected high-energy emission from GRB 170522A, which was also detected by Fermi-GBM (trigger 517160740 / 170522657, Stanbro et al., GCN 21126).
The best LAT on-ground location is found to be RA, Dec = 139.34, 25.67 (J2000) with an error radius of 0.19 deg (90 % containment, statistical error only).
This was 50 deg from the LAT boresight at the time of the trigger and triggered an autonomous repoint of the spacecraft. The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the GBM trigger with high significance. The highest-energy photon is a 3.7 GeV event which is observed 8 seconds after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Judith Racusin (judith.racusin@nasa.gov).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
GCN Circular #21128
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 Fermi/LAT GRB 170522A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00068
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 Fermi/LAT 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 #21129
D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report:
The long GRB 170522A (Fermi-GBM detection: Stanbro & Meegan, GCN 21126; Fermi-LAT detection: Arimoto & Racusin, GCN 21127) triggered Konus-Wind at T0=3D56735.921 s UT (15:45:35.921)
The burst light curve shows a multi-peaked pulse with a total duration of ~7.4 s. The emission is seen up to ~10 MeV.
As observed by Konus-Wind, the burst had a fluence of (3.8 =B1 0.4)x10^-5 erg/cm2 and a 64-ms peak energy flux, measured from T0+2.048 s of (1.41 =B1 0.14)x10^-5 erg/cm2 (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+13.568 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.48 (-0.20,+0.22), the high energy photon index beta =3D -2.42 (-0.38,+0.20), the peak energy Ep =3D 289 (-37,+49) keV, chi2 =3D 97/97 dof.
The spectrum near the peak count rate (measured from T0 to T0+5.376 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.39 (-0.17,+0.20), the high energy photon index beta =3D -2.49 (-0.31,+0.19), the peak energy Ep =3D 312 (-36,+42) keV, chi2 =3D 88/97 dof.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170522_T56735/
All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.
GCN Circular #21132
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, D.Kuvshinov, A.V.Krylov, I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova Irkutsk State University
D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory
R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina
H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina
V.Yurkov, Yu.Sergienko Blagoveschensk Educational State University, Blagoveschensk
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias
MASTER Tunka robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was pointed to the GRB170522A 36 sec after notice time and 136 sec after trigger time at 2017-05-22 15:47:51 UT. On our first (30s exposure) set we do not OT within GBM FERMI error-box (ra=135.417 dec=27.0394 r=1.26 see Stanbro and Meegan GCN #21126 ) brighter then 16.2.
Unfortunately this observation was outside of the future Fermi LAT (Arimoto and Racusin, GCN #21127) error box.
Fortunatelly, we have MASTER Very Wide field cameras on all telescopes (5-10 sec exposure on 2x380 square degrees FOV) and we have images with future Fermi LAT (Arimoto and Racusin, GCN #21127) error box. There is no OT brighter ~12 mag inside the future Fermi LAT error box.
The observations made on zenit distance = 66 degrees, galaxy latitude b = 40 degree. The moon (14 % bright part) below the horizon (The altitude of the Moon is -32 degree ). Observations started at twilight. The sun altitude is -15.9 degree. The area can be observed till sunrise at 2017-05-22 21:04:48
MASTER SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was automaticaly starting survey on the FERMI GRB170522A error-box (ra=09 01 47 dec=+27 07 12 r=1 Fermi GBM error box Stanbro and Meegan GCN #21126 ) 3186 sec after notice time and 3740 sec after trigger time at 2017-05-22 16:47:55 UT. The 5-sigma upper limit on our first (60s exposure) set is about 18.7mag No OT brighter 19.5 detected in SAAO.
The observations made on zenit distance = 62 degrees, galaxy latitude b = 40 degree. The moon (14 % bright part) below the horizon (The altitude of the Moon is -39 degree ). Observations started at twilight. The sun altitude is -13.9 degree. The object can be observed till sunrise at 2017-05-23 05:22:11
Unfortunately this observation was outside of the future Fermi LAT (Arimoto and Racusin, GCN #21127) error box.
MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in OAFA automaticaly was pointed to the GRB170522A 247 sec after FERMI LAT notice time (Arimoto and Racusin, GCN #21127) and 35103 sec after trigger time at 2017-05-23 01:30:38 UT . But zenit distance was very high and we received dark images.
On our 4-th image (923 sec after FERMI LAT notice time (Arimoto and Racusin, GCN #21127) and 35779 sec after trigger time at 2017-05-23 01:41:54 UT.) we found 1 short optical transient within LAT error-box (ra=139.338 dec=25.67 r=0.19) brighter then 14.5 .
```
  T-Tmid      Date      Time       Expt.        Ra                Dec           Mag
---------|---------------------|-------|-----------------|-----------------|-------
    35869   2017-05-23 01:41:54     180   (  9h 16m 35.3s , +25d 41m 07.4s)    13.72
```
This object was found only on the one image. The 5-sigma upper limit has been about 14.5 mag We did not find OT brighter 18.5 on the next images.
The observations made on zenit distance = 80 degrees, galaxy latitude b = 43 degree. The moon (11 % bright part) below the horizon (The altitude of the Moon is -63 degree ). The sun altitude is -50.3 degree. The object can be observed till 2017-05-23 02:44:45 .
The message may be cited.
GCN Circular #21133
B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 170522A (Arimoto et al. GCN Circ. 21127) in a series of observations tiled on the sky. The total exposure time is 4.7 ks, distributed over 5 tiles; the maximum exposure at a single sky location was 3.3 ks. The data were collected between T0+39.4 ks and T0+51.3 ks, and are entirely in Photon Counting (PC) mode.
Four 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):  139.1534  =  09:16:36.82
  Dec (J2000.0): +25.4844  =  +25:29:03.9
  Error: 3.8 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (9.7 [+3.1, -2.6])e-3 ct s^-1   
  Distance: 901 arcsec from Fermi/LAT position.
  Flux: (4.2 [+1.3, -1.1])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
Source 2:
```
  RA (J2000.0):  139.2381  =  09:16:57.13
  Dec (J2000.0): +25.4737  =  +25:28:25.5
  Error: 6.0 arcsec (radius, 90% conf.)
  Count-rate: (6.7 [+3.3, -2.5])e-3 ct s^-1   
  Distance: 780 arcsec from Fermi/LAT position.
  Flux: (4.4 [+2.2, -1.6])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
Source 3:
```
  RA (J2000.0):  139.1099  =  09:16:26.38
  Dec (J2000.0): +25.8756  =  +25:52:32.2
  Error: 6.5 arcsec (radius, 90% conf.)
  Count-rate: (6.6 [+2.9, -2.2])e-3 ct s^-1   
  Distance: 1050 arcsec from Fermi/LAT position.
```
Source 4:
```
  RA (J2000.0):  139.0535  =  09:16:12.85
  Dec (J2000.0): +25.6179  =  +25:37:04.5
  Error: 10.2 arcsec (radius, 90% conf.)
  Count-rate: (5.6 [+3.1, -2.3])e-3 ct s^-1   
  Distance: 948 arcsec from Fermi/LAT position.
```
The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00068.
This circular is an official product of the Swift-XRT team.
GCN Circular #21134
C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc (U. Nova Gorica), C.G. Mundell (U. Bath), A. Cucchiara, D. Morris, B. Gendre (U. of Virgin Islands) on behalf of a large collaboration report:
We began observing Fermi-LAT GRB 170522A (Arimoto et al. GCN 21127; Stanbro et al. GCN 21126; Lipunov et al. GCN 21132) on May 23, 03:07 UT (11.4 hours since the GRB) with the 1-m LCO unit at the LCO McDonald observatory with the SDSS i filter. Within the LAT error circle we do not detect any uncatalogued source down to i~19 mag in a 3x120s stacked frame, as calibrated against nearby SDSS stars. Although all of the four X-ray sources reported by Swift-XRT (Mingo et al. GCN 21133) lie outside the LAT error circle, three of them (Sources 1, 2, 3) happen to lie within our field of view. We did not find uncatalogued counterparts in any of the corresponding error circles down to the same limit.
GCN Circular #21138
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,
V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa, and A. Goldstein, on behalf of the Fermi GBM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer, on behalf of the Swift-BAT 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 170522A (Fermi-GBM detection: Stanbro and Meegan, GCN Circ. 21126; Fermi-LAT detection: Arimoto and Racusin, GCN Circ. 21127; Konus-Wind observation: Frederiks et al., GCN Circ. 21129) was detected by Fermi (GBM trigger 517160740), Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), and Swift (BAT), at about 56735 s UT (15:45:35). The burst was outside the coded field of view of the BAT.
We have triangulated it to a GBM-HEND annulus centered at RA(2000)=80.195 deg (05h 20m 47s) Dec(2000)=+23.945 deg (+23d 56' 40"), whose radius is 53.106 +/- 0.070 deg (3 sigma).
The LAT position reported by Arimoto and Racusin (GCN Circ. 21127) is consistent with the annulus. The annulus combined with the LAT (90 % containment, statistical-only) error circle gives the following error box:
```
---------------------------------------------
  RA(2000), deg  Dec(2000), deg
---------------------------------------------
Center:
     139.1949    +25.6971
Corners:
     139.1335    +25.7084
     139.2170    +25.5157
     139.2562    +25.6856
     139.2950    +25.8556
---------------------------------------------
```
The error box area is 101.5 sq. arcmin (a factor of 4 smaller that that of LAT error circle).
This box may be improved.
None of the Swift-XRT sources reported by Mingo et al. (GCN Circ. 21133) are consistent with the box, and only Source 1 is consistent with the annulus.
A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB170522_T56735/IPN
GCN Circular #21201
K.L. Page and S.L. Gibson (U. Leicester) report on behalf of the Swift-XRT team:
Swift has performed further observations of the field of the Fermi/LAT-detected burst GRB 170522A (Arimoto et al., GCN Circ. 21127). An additional 3.5 ks of data were collected between 987 ks and 999 ks after the Fermi trigger.
Source 1, initially reported by Mingo et al. (GCN Circ. 21133), is no longer detected to a 3-sigma upper limit of 4.3e-3 ct s^-1. We therefore conclude that this source is likely the X-ray afterglow of GRB 170522A.
This circular is an official product of the Swift-XRT team.

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Jochen Greiner, last update: 05-Jun-2017 [Disclaimer]