Gamma-ray Burst 190530A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 30 May 19 10:19:42 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      60
TRIGGER_NUM:     580904353
GRB_RA:          131.667d {+08h 46m 40s} (J2000),
                 131.976d {+08h 47m 54s} (current),
                 130.869d {+08h 43m 29s} (1950)
GRB_DEC:         +36.800d {+36d 47' 60"} (J2000),
                 +36.728d {+36d 43' 41"} (current),
                 +36.984d {+36d 59' 01"} (1950)
GRB_ERROR:       3.38 [deg radius, statistical plus systematic]
GRB_INTEN:       6478 [cnts/sec]
DATA_SIGNIF:     324.30 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        18633 TJD;   150 DOY;   19/05/30
GRB_TIME:        37148.90 SOD {10:19:08.90} UT
GRB_PHI:          50.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.70
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   2%  Distant Particles
DETECTORS:       1,0,0, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        67.02d {+04h 28m 06s}  +21.76d {+21d 45' 24"}
SUN_DIST:         57.53 [deg]   Sun_angle= -4.3 [hr] (East of Sun)
MOON_POSTN:       20.65d {+01h 22m 35s}   +3.14d {+03d 08' 29"}
MOON_DIST:       104.97 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      185.95, 38.06 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      124.07, 18.16 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_lc_medres34_bn190530430.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 204.75,20.72 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 30 May 19 10:19:45 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      59
TRIGGER_NUM:     580904353
GRB_RA:          117.500d {+07h 50m 00s} (J2000),
                 117.815d {+07h 51m 16s} (current),
                 116.688d {+07h 46m 45s} (1950)
GRB_DEC:         +34.670d {+34d 40' 12"} (J2000),
                 +34.620d {+34d 37' 11"} (current),
                 +34.797d {+34d 47' 48"} (1950)
GRB_ERROR:       1.17 [deg radius, statistical only]
DATA_SIGNIF:     180.40 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        18633 TJD;   150 DOY;   19/05/30
GRB_TIME:        37148.90 SOD {10:19:08.90} UT
GRB_PHI:          39.00 [deg]
GRB_THETA:        62.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:        67.02d {+04h 28m 06s}  +21.76d {+21d 45' 24"}
SUN_DIST:         46.07 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:       20.65d {+01h 22m 36s}   +3.14d {+03d 08' 30"}
MOON_DIST:        94.09 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      185.59, 26.38 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      112.98, 13.40 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_lc_medres34_bn190530430.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_580904353.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
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:     Thu 30 May 19 10:20:02 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      75
TRIGGER_NUM:     580904353
GRB_RA:          130.683d {+08h 42m 44s} (J2000),
                 130.983d {+08h 43m 56s} (current),
                 129.910d {+08h 39m 38s} (1950)
GRB_DEC:         +31.883d {+31d 52' 60"} (J2000),
                 +31.813d {+31d 48' 46"} (current),
                 +32.063d {+32d 03' 48"} (1950)
GRB_ERROR:       3.35 [deg radius, statistical plus systematic]
GRB_INTEN:       8294 [cnts/sec]
DATA_SIGNIF:     838.70 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        18633 TJD;   150 DOY;   19/05/30
GRB_TIME:        37148.90 SOD {10:19:08.90} UT
GRB_PHI:          52.00 [deg]
GRB_THETA:        60.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.53
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      90%  GRB
2nd_MOST_LIKELY:   5%  Distant Particles
DETECTORS:       1,0,0, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        67.02d {+04h 28m 06s}  +21.76d {+21d 45' 24"}
SUN_DIST:         57.19 [deg]   Sun_angle= -4.3 [hr] (East of Sun)
MOON_POSTN:       20.65d {+01h 22m 36s}   +3.14d {+03d 08' 33"}
MOON_DIST:       105.42 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      191.86, 36.41 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      124.65, 13.21 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_lc_medres34_bn190530430.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 204.75,20.72 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 30 May 19 10:19:33 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      48
TRIGGER_NUM:     580904353
GRB_RA:          131.700d {+08h 46m 48s} (J2000),
                 132.008d {+08h 48m 02s} (current),
                 130.904d {+08h 43m 37s} (1950)
GRB_DEC:         +36.550d {+36d 32' 60"} (J2000),
                 +36.478d {+36d 28' 40"} (current),
                 +36.734d {+36d 44' 02"} (1950)
GRB_ERROR:       4.45 [deg radius, statistical plus systematic]
GRB_INTEN:       2373 [cnts/sec]
DATA_SIGNIF:     81.20 [sigma]
INTEG_TIME:      0.512 [sec]
GRB_DATE:        18633 TJD;   150 DOY;   19/05/30
GRB_TIME:        37148.90 SOD {10:19:08.90} UT
GRB_PHI:          50.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 0.5120 [sec]
HARD_RATIO:      1.10
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      94%  GRB
2nd_MOST_LIKELY:   3%  Distant Particles
DETECTORS:       1,0,0, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        67.02d {+04h 28m 06s}  +21.76d {+21d 45' 24"}
SUN_DIST:         57.58 [deg]   Sun_angle= -4.3 [hr] (East of Sun)
MOON_POSTN:       20.65d {+01h 22m 35s}   +3.14d {+03d 08' 28"}
MOON_DIST:       105.06 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      186.27, 38.06 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      124.17, 17.93 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_lc_medres34_bn190530430.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 204.75,20.72 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 30 May 19 10:19:51 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      72
TRIGGER_NUM:     580904353
GRB_RA:          131.650d {+08h 46m 36s} (J2000),
                 131.959d {+08h 47m 50s} (current),
                 130.852d {+08h 43m 24s} (1950)
GRB_DEC:         +36.900d {+36d 53' 60"} (J2000),
                 +36.828d {+36d 49' 41"} (current),
                 +37.084d {+37d 05' 01"} (1950)
GRB_ERROR:       3.45 [deg radius, statistical plus systematic]
GRB_INTEN:       4734 [cnts/sec]
DATA_SIGNIF:     466.20 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        18633 TJD;   150 DOY;   19/05/30
GRB_TIME:        37148.90 SOD {10:19:08.90} UT
GRB_PHI:          50.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.80
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   2%  Distant Particles
DETECTORS:       1,0,0, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        67.02d {+04h 28m 06s}  +21.76d {+21d 45' 24"}
SUN_DIST:         57.51 [deg]   Sun_angle= -4.3 [hr] (East of Sun)
MOON_POSTN:       20.65d {+01h 22m 36s}   +3.14d {+03d 08' 31"}
MOON_DIST:       104.93 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      185.82, 38.06 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      124.03, 18.25 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_lc_medres34_bn190530430.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 204.75,20.72 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Thu 30 May 19 10:20:32 UT 
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    8289,   Sub_Num: 0
GRB_INTEN:      9.44 [sigma]
GRB_TIME:       37147.46 SOD {10:19:07.46} UT 
GRB_DATE:       18633 TJD;   150 DOY;   19/05/30
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:       Time_Scale=2.0000 and Time_Error=1.0000. 
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=580904353).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2019-05/2019-05-30T10-19-07.2802-06116-11152-0.lc

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 30 May 19 10:28:12 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     580904353
GRB_RA:          116.920d {+07h 47m 41s} (J2000),
                 117.233d {+07h 48m 56s} (current),
                 116.111d {+07h 44m 27s} (1950)
GRB_DEC:         +33.950d {+33d 57' 00"} (J2000),
                 +33.901d {+33d 54' 03"} (current),
                 +34.074d {+34d 04' 27"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
GRB_DATE:        18633 TJD;   150 DOY;   19/05/30
GRB_TIME:        37148.90 SOD {10:19:08.90} UT
GRB_PHI:          39.00 [deg]
GRB_THETA:        63.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:        67.03d {+04h 28m 07s}  +21.76d {+21d 45' 27"}
SUN_DIST:         45.56 [deg]   Sun_angle= -3.3 [hr] (East of Sun)
MOON_POSTN:       20.72d {+01h 22m 52s}   +3.17d {+03d 10' 09"}
MOON_DIST:        93.63 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      186.21, 25.72 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      112.63, 12.60 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_lc_medres34_bn190530430.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_locplot_all_bn190530430.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        Bright hard burst in the GBM.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=8289).

GCN Circular #24676
The Fermi GBM team reports the detection of a likely LONG GRB
At 10:19:08 UT on 30 May 2019, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 190530A (trigger 580904353.903198 / 190530430).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 116.9, Dec = 34.0 (J2000 degrees, equivalent to J2000 07h 47m, 34d 00'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 63.0 degrees.
The skymap can be found here: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_skymap_all_bn190530430.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_healpix_all_bn190530430.fit
The GBM light curve can be found here: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190530430/quicklook/glg_lc_medres34_bn190530430.gif
GCN Circular #24677
B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 580904353 at 10:19:08 on 30 May 2019 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60).
The best-fit position (1 sigma statistical errors) is:
```
RA(2000.0) = 120.7+/-0.3 deg
Decl.(2000.0) = 36.1+/-0.2 deg
```
We estimate an additional systematic error of 1 deg.
Further details are available at: https://grb.mpe.mpg.de/grb/GRB190530430/
The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB190530430/healpix
The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB190530430/json
GCN Circular #24678
F. Lucarelli, C. Pittori, F. Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, M. Feroci, G. Piano, A. Ursi (INAF/IAPS), A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:
The AGILE Mini-CALorimeter (MCAL) detected GRB 190530A at T0 = 2019-05-30 10:19:16.003 +/- 0.01 s (UTC), which was also detected by Fermi/GBM (GCN #24676). The AGILE MCAL trigger occured around 8 s after the FERMI/GBM trigger.
An automatic MCAL Event Notice was also issued and is available at the GCN link: https://gcn.gsfc.nasa.gov/agile_mcal.html
The event lasted about 12 s and released a total number of ~30900 counts in the detector (in the 0.4-100 MeV energy range), above an average background rate of 637 counts/s.
The light curve shows two structures and several peaks, with a prompt emission lasting around 1.6s and then, after about 5 s from T0, a second structure lasting for around 7 s with the highest peak at around T0+7s.
The plot of the AGILE-MCAL light curve can be found at: https://tools.ssdc.asi.it/ImgView/Agile/GRB190530A_AGILE-MCAL16
Bright emission in the 17-60 keV energy range is also detected by the SuperAGILE instrument on-board of AGILE.
The GRB is clearly detected also by the AGILE scientific ratemeters: in particular, the Anti-Coincidence (50-200 keV), SuperAGILE (20-60 keV), and MCAL (0.4-100 MeV) ratemeters.
The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress.

GCN Notice

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 30 May 19 18:11:50 UT
NOTICE_TYPE:     Fermi-LAT Offline Position
TRIGGER_NUM:     580904353
GRB_RA:          120.762d {+08h 03m 03s} (J2000),
                 121.077d {+08h 04m 18s} (current),
                 119.950d {+07h 59m 48s} (1950)
GRB_DEC:         +35.502d {+35d 30' 07"} (J2000),
                 +35.446d {+35d 26' 47"} (current),
                 +35.643d {+35d 38' 34"} (1950) 
GRB_ERROR:       10.20 [arcmin radius, 90% containment, statistical only]  
GRB_DATE:        18633 TJD;   150 DOY;   19/05/30
GRB_TIME:        37148.00 SOD {10:19:08.00} UT
TRIGGER_ID:      0x20000000
MISC:            0x40000000
SUN_POSTN:        67.36d {+04h 29m 26s}  +21.81d {+21d 48' 18"}
SUN_DIST:         48.47 [deg]   Sun_angle= -3.6 [hr] (East of Sun)
MOON_POSTN:       24.46d {+01h 37m 51s}   +4.68d {+04d 40' 40"}
MOON_DIST:        92.65 [deg]  
MOON_ILLUM:      15 [%]
GAL_COORDS:      185.46, 29.18 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      115.50, 14.75 [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 of GRB 190530A.     
COMMENTS:        This source corresponds to GBM trigger.

GCN Circular #24679
F. Longo (University and INFN, Trieste), J. L. Racusin (NASA/GSFC), N. Omodei (Stanford), and E.Bissaldi (Politecnico & INFN Bari) report on behalf of the Fermi-LAT Collaboration:
At 10:19:08 UT on 2019-05-30, Fermi-LAT triggered on high-energy emission from long GRB 190530A, which was also detected by Fermi-GBM (GCN 24676) and AGILE-MCAL (GCN 24678).
The best LAT on-ground location is found to be: RA, Dec = 120.76, 35.5 (J2000) with an error radius of 0.12 deg (90% containment, statistical error only).
This was 63 deg from the LAT boresight at the time of the trigger and 3.5 deg from the center of the GBM localization (GCN 24676).
The data from the Fermi-LAT show a significant increase in the event rate that is temporally correlated with the GBM emission with high significance.
The highest-energy photon is a 8.7 GeV event which is observed 96 seconds after the GBM trigger. The photon flux above 100 MeV in the time interval 0-200s after the GBM trigger is 2.9 e-04 ph/cm2/s +/- 2.9 e-05.
The estimated photon index above 100 MeV is -2.7 +/- 0.1.
The Fermi-LAT point of contact for this burst is Francesco Longo (francesco.longo@ts.infn.it).
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 #24680
V. Lipunov (Lomonosov MSU), D.Svinkin (Ioffe Institute), O.Gress, A.Kuznetsov, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov, P.Balanutsa, F.Balakin, E. Gorbovskoy, A. Chasovnikov, V.Topolev, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA, San Juan National University),
H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE, SJNU)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O. Gress, N.M. Budnev, O.Ershova, Yu.Ishmuhametova, S.Yazev (Applied Physics Institute, Irkutsk State University),
V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University),
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
MASTER-Kislovodsk robotic telescope (MASTER Global Robotic Net http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy,vol. 2010, 30L) automatically was pointed to the GRB190530A Fermi LAT localization (Longo et al GCN 24679) (also inspected BALROG localization Biltzinger et al. GCN 24677 and Fermi team error-box GCN 24676) at 2019-05-30 18:12:10 (sun altitute= -16deg., alert_altitute=23deg.)
We detect MASTER OT J080207.73+352847.7 (RA,Dec2000)=08h 02m 07.73s +35d 28m 47.7s with m_OT=16.7m (but in 3.8" there is optical source at PANSTARRs images with rmag=20.9, gmag=22.6)
OT is inside Barlog error box (GCN 24677). The covered map and OT place is available at https://master.sai.msu.ru/site/master2/event.php?id=1034468
Observation and reduction will be continued. The message may be cited.
GCN Circular #24681
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Fermi/LAT GRB 190530A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/ToO_GRBs/00020893
Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/LAT event. 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 #24683
F. Verrecchia, F. Lucarelli, C. Pittori (SSDC, and INAF/OAR), G. Piano (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo, Y. Evangelista, A. Ursi (INAF/IAPS), (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino (INAF/OAS), M. Marisaldi (INAF/OAS, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), F. Longo (Univ. Trieste and INFN Trieste), I. Donnarumma (ASI), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:
The Gamma-Ray Imaging Detector (GRID) of AGILE detected a gamma-ray transient temporally coincident with the long GRB 190530A reported by Lucarelli et al., GCN #24678 and also detected and localized by Fermi/GBM (GCN #24676) and Fermi/LAT (GCN #24679).
A preliminary GRID analysis in the energy range 30 MeV - 1 GeV shows a detection with a statistical significance of about 4 sigma, at the sky position R.A., Decl. (J2000): 120,+34 � 5 deg (Galactic coordinates l,b: 187,+28 deg), over a time integration of 500 s starting from the T0 of GRB 190530A.
This preliminary estimated position was above 30 deg from the GRID boresight.
These measurements were obtained with AGILE observing a large portion of the sky in spinning mode. Additional analysis of AGILE data is in progress.
GCN Circular #24684
D. A. Kann, L. Izzo (both HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), M. Blazek, C. C. Thoene, K. Bensch (all HETH/IAA-CSIC), and V. Casanova (IAA-CSIC) report:
We observed the afterglow position (Lipunov et al., GCN 24680) of the extremely bright GRB 190530A (GBM detection and localization: Fermi GBM team, GCN 24676, Biltzinger et al., GCN 24677; Fermi-LAT localization: Longo et al., GCN 24679; Agile-MCAL/GRID detections: Lucarelli et al., GCN 24678, Verecchia et al., GCN 24683) with the 1.5-m telescope of the Sierra Nevada Observatory (OSN), Spain. The afterglow is well-detected.
We measure the following AB magnitude:
Rc = 17.63 +- 0.10 mag at 0.437314 days after the GRB.
The magnitude were derived against 1 nearby star from the SDSS catalog, using the transformation equations of Lupton (2005), and transformed back into AB mag.
We note this is an exceedingly bright afterglow, further follow-up is encouraged despite the bad visibility.
GCN Circular #24685
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Vladimirov, D. Vlasenko, 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-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB190530.43 (trigger No 580904353, 7h 47m 40.80s , +33d 57m 00.00s, R=1) errorbox 15845 sec after trigger time at 2019-05-30 14:43:13 UT, with upper limit up to 17.0 mag. Observations started at twilight. The observations began at zenit distance = 67 deg. The sun altitude is -10.9 deg.
MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB190530.43 errorbox 37305 sec after trigger time at 2019-05-30 20:40:53 UT, with upper limit up to 18.6 mag. Observations started at twilight. The observations began at zenit distance = 55 deg. The sun altitude is -10.0 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=1034101
We obtain a following upper limits.
```
Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________


   15875 | 2019-05-30 14:43:13 |        MASTER-Tunka | (  7h 54m 57.60s , +34d 16m 22.90s) |   C |    60 | 17.0 |        
   37335 | 2019-05-30 20:40:53 |          MASTER-IAC | (  7h 48m 30.78s , +36d  2m 17.88s) |   C |    60 | 16.1 |        
   39657 | 2019-05-30 21:19:35 |          MASTER-IAC | (  7h 48m 29.33s , +36d  1m 46.41s) |   C |    60 | 18.5 |        
   39857 | 2019-05-30 21:22:55 |          MASTER-IAC | (  7h 56m 27.73s , +34d  2m 23.67s) |   C |    60 | 18.5 |        
   40255 | 2019-05-30 21:29:33 |          MASTER-IAC | (  7h 56m 29.16s , +34d  2m 02.86s) |   C |    60 | 18.5 |        
   42339 | 2019-05-30 22:04:17 |          MASTER-IAC | (  7h 37m 09.44s , +34d  1m 36.98s) |   C |    60 | 18.6 |        
   42742 | 2019-05-30 22:10:59 |          MASTER-IAC | (  7h 37m 09.55s , +34d  1m 34.63s) |   C |    60 | 18.5 |        
   42838 | 2019-05-30 22:12:35 |          MASTER-IAC | (  7h 46m 48.61s , +34d  1m 29.99s) |   C |    60 | 18.4 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #24686
K. E. Heintz (Univ. of Iceland), J. P. U. Fynbo (DAWN/NBI), A. de Ugarte Postigo (HETH/IAC and DARK/NBI), D. B. Malesani (DTU Space), J. Selsing (DAWN/NBI), B. Milvang-Jensen (DAWN/NBI) and S. Moran (NOT and Univ. of Turku), report on behalf of a larger collaboration:
We observed the optical counterpart (Lipunov et al., GCN 24680) of the bright Fermi-LAT GRB 190530A (Longo et al., GCN 24679), with the 2.5-m Nordic Optical Telescope (NOT) equipped with ALFOSC, starting at 21:21:12 UT on 30 May 2019. We obtained 30 s images in each of the g, r, i, and z-filters and measure magnitudes of: m(g) = 17.72 +/- 0.03, m(r) = 17.53 +/- 0.02, m(i) = 17.41 +/- 0.02, and m(z) = 17.37 +/- 0.03 AB mag at 11.2 hr post-burst. The calibration was performed using local Pan-STARRS stars in the GRB field. This apparent magnitudes are not corrected for foreground extinction.
We subsequently obtained spectroscopy for a total of 2x600 s, using grism #4 and covering the wavelength range 3650-9450 AA. The spectrum shows a blue, power-law continuum from 3900 AA to 9000 AA. We do not detect any significant absorption or emission lines in our low-resolution spectrum, but based on the detected continuum we infer an upper limit on the redshift of z < 2.2. We encourage the community to obtain spectra of this GRB with bluer wavelength coverage.
GCN Circular #24687
L. Izzo (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, M. Blazek, C. C. Thoene, K. Bensch (all HETH/IAA-CSIC), J.L. Lamadrid, F. López-Martínez, M. C. Díaz-Martín andH. Vazquez Ramio (all CEFCA) report:
We observed the field of GRB 190530A (Fermi-GBM team, GCN 24676; Biltzinger et al., GCN 24677; Longo et al., GCN 24679; Lucarelli et al., GCN 24678; Verecchia et al., GCN 24683) with the 0.8m telescope of the Observatorio Astrofisico de Javalambre (Teruel, Spain). Observations consisted of a series of 300 s g'r'i' exposures, starting at 20:53:37 UT (0.44 days after the GRB trigger). We do not detect any source within the LAT error circle (Longo et al., GCN 24679) itself down to the DSS2 limit.
The afterglow reported by Lipunov et al. (GCN 24680) is clearly detected at the following position (J2000.0, +/-0.5"):
```
RA =  08:02:07.84
Dec. = +35:28:47.1
```
consistent with the position reported by Lipunov et al. We note this position lies outside the Fermi LAT error circle. We measure the following magnitudes, as compared to a nearby SDSS star:
```
filter |     mag (AB)     | time (days)

g       |  17.91 +- 0.07  |  0.444
r       |  17.56 +- 0.08  |  0.448
i       |  17.38 +- 0.08  |  0.440
```
GCN Circular #24688
L. P. Xin, G. W. Li, R. S. Zhang, T. C. Zheng, J. Wang, J. Y. Wei, Y. G. Yang, E. W. Liang, X. G. Wang, H. L. Li, X. H. Han, X. M. Lu, L. Huang, H. B. Cai, Y. L. Qiu, Y. Xu, Y. J. Xiao, Y. T. Zheng, C. Wu, J. S. Deng, D. W. Xu, D. Turpin, W. L. Dong, P. P. Zhang and Jirong Mao report:
We began to observe GRB 190530A (Fermi-GBM team, GCN 24676 ) with GWAC-F30cm telescope at 2019-05-30T12:48:46(UT), about 2.49 hour after the burst. GWAC-F30cm telescope is located at Xinglong observatory, China. The field of view is about 1.9*1.9 sqr. deg. The coordinates we used to make the observations was derived from Biltzinger et al., (GCN 24677). Due to the low elevation of this source at Xinglong observatory, only seven R-band images were obtained. The exposure time for each frame was 20 seconds.
The afterglow was detected by stacking all the images. The coordinates is about RA=08:02:07.678 DEC=+35:28:47.14 J2000, consistent with the position reported by Lipunov et al., GCN 24680. The magnitude was R=15.1mag, calibrated by the nearby USNO R2 magnitudes.
This message my be cited.
GCN Circular #24689
A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernadini (INAF-OAB) 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 190530A (Longo et al. GCN Circ. 24679), collecting 3.1 ks of Photon Counting (PC) mode data between T0+33.8 ks and T0+50.4 ks.
Four uncatalogued X-ray sources are detected, of which one ("Source 5") is above the RASS limit, and is therefore likely the GRB afterglow. This source is coincident with the location of the optical counterpart candidate reported by MASTER (Lipunov et al., GCN 24680). Using 2727 s of PC mode data and 6 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 = 120.53242, +35.47947 which is equivalent to:
```
RA (J2000): 08h 02m 07.78s
Dec(J2000): +35d 28' 46.1"
```
with an uncertainty of 1.4 arcsec (radius, 90% confidence). This position is 11.3 arcmin from the Fermi/LAT position.
The light curve can be modelled with a power-law decay with a decay index of alpha=2.2 (+/-0.4).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.70 (+/-0.11). The best-fitting absorption column is 1.1 (+0.4, -0.3) x 10^21 cm^-2, in excess of the Galactic value of 5.1 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 3.6 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.1 (+0.4, -0.3) x 10^21 cm^-2
Galactic foreground: 5.1 x 10^20 cm^-2
Excess significance: 3.1 sigma
Photon index:	     1.70 (+/-0.11)
```
If the light curve continues to decay with a power-law decay index of 2.2, the count rate at T+24 hours will be 0.13 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.7 x 10^-12 (5.5 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020893. The results of the full analysis of the XRT observations are available at http://www.swift.ac.uk/ToO_GRBs/00020893.
This circular is an official product of the Swift-XRT team.
GCN Circular #24690
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Diego Gonz�lez (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Margarita Pereyra (UNAM), and Eleonora Troja (GSFC) report:
We observed the field of Fermi GBM/LAT GRB 190530A (Fermi GBM Team, GCN Circ. 24676; Longo et al., GCN Circ. 24679) with the COATLI 50-cm telescope and interim imager at the Observatorio Astron�mico Nacional on the Sierra de San Pedro M�rtir (http://coatli.astroscu.unam.mx) from 2019-05-31 03:33 to 06:27 (from 17.2 to 20.1 hours after the trigger), obtaining a total of 8190 seconds of exposure in the w filter.
We detect the afterglow (Lipunov et al., GCN Circ. 24680; Melandri et al., GCN Circ. 24689) at
w = 18.18 +/- 0.01
During our observations, the afterglow fades with a power-law index of -1.05 +/ 0.25.
Our w magnitudes are calibrated against the Pan-STARRS1 catalog, are on an approximate AB system, and are not corrected for Galactic extinction in the direction of the GRB.
We thank the COATLI technical team and the staff of the Observatorio Astron�mico Nacional.
GCN Circular #24692
E. Bissaldi (Politecnico & INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 10:19:08.90 UT on 30 May 2019, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 190530A (trigger 580904353 / 190530430, GCN #24676), which was also detected by AGILE-MCAL (GCN # 24678) and Fermi-LAT (GCN # 24679).
The GBM light curve consists of multiple bright peaks with a duration (T90) of about 18.4 s (50-300 keV).
The time-averaged spectrum from T0 to T0+20 s is adequately fit by a Band function with Epeak = 900 +/- 10 keV, alpha = -1.00 +/- 0.01, and beta = -3.64 +/- 0.12.
The event fluence (10-1000 keV) in this time interval is (3.72 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux measured starting from T0+16.4 s in the 10-1000 keV band is 160.5 +/- 0.7 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/"
GCN Circular #24693
V. Lipunov (Lomonosov MSU), D.Svinkin (Ioffe Institute), J.Greiner (MPG, Germany), D.Vlasenko, O.Gress, I.Gorbunov, E.Gorbovskoy, A.Kuznetsov, V.Kornilov, V.Vladimirov, P.Balanutsa, D.Zimnukhov, F.Balakin, N.Tiurina, A. Chasovnikov, V.Topolev, V.Senik, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department),
V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University),
O. Gress, N.M. Budnev, O.Ershova, S.Yazev (Applied Physics Institute, Irkutsk State University),
A. Tlatov, D.Dormidontov, A.V. Parhomenko (Kislovodsk Solar Station of the Pulkovo Observatory),
R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA, San Juan National University),
H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE, SJNU)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
MASTER Global Robotic Net (Lipunov et al., 2010, Advances in Astronomy,vol.2010, 30L (http://observ.pereplet.ru) observed Fermi GRB 190530A (GBM team GCN 24676, BALROG Biltzinger et al.GCN 24677, LAT Longo et al. GCN 24679 and IPN localization; gamma-ray transient also detected by AGILE 8s later Lecarelli et al. GCN 24678, Verrecchia et al. GCN 24683) in MASTER-Amur, MASTER-Tunka, MASTER-SAAO, MASTER-Kislovodsk, MASTER-Tavrida, MASTER-IAC (the order in accordance with sunset).
MASTER auto-detection system discovered MASTER OT J080207.73+352847.7 = AT 2019gdw (https://wis-tns.weizmann.ac.il/object/2019gdw ) at (RA,Dec2000)=08h 02m 07.73s +35d 28m 47.7s( Lipunov et al. GCN24680)
MASTER-Amur robotic telescope automatically was pointed to the Fermi GRB190530A BALROG localization at 2019-05-30 14:34:09 (error-box altitude = 13 (and go down), sun_alt=-17 very cloudy weather at sunset) with automatic photometry m_OT ~ 14.8
MASTER-Tunka robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 14:43:13UT (error_box_alt=26deg., sun_alt=-10deg.), automatic photometry m_OT ~ 16.5
MASTER-SAAO robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 16:34:41UT (very cloudy all horizont, error-box_alt=13.5 and go down, sun_alt=-11) mlim=14.5
MASTER-Kislovodsk robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 18:12:10 (sun altitute= -16deg., alert_altitute=23deg.) automatic photometry m_OT~16.7
MASTER-Tavrida robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 2019-05-30 18:12:17 (sun altitute= -8deg., alert_altitute=34deg.) automatic photometry m_OT~16.7
MASTER-IAC robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 20:50:32UT (sun altitute=-11 deg., alert_altitute=36 deg.) automatic photometry unfiltered m_OT~17.4
The covered map and OT place is available at https://master.sai.msu.ru/site/master2/event.php?id=1034468
Observation and reduction will be continued. The message may be cited.
ATEL #12824
MASTER OT J080207.73+352847.7 discovery - optical afterglow of very bright GRB190530A
D. Vlasenko, V. Lipunov (Lomonosov MSU), D. Svinkin (Ioffe Institute), J. Greiner (MPG, Germany), O. Gress, I. Gorbunov, A. Kuznetsov, E. Gorbovskoy, P. Balanutsa, N. Tiurina, V. Kornilov, V. Vladimirov, D. Zimnukhov, F. Balakin, A. Chasovnikov, V. Topolev, V. Senik, V. Grinshpun, T. Pogrosheva, D. Kuvshinov (Lomonosov MSU), V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (BSPU), N. M. Budnev, O. Ershova (API ISU), A. Tlatov, D. Dormidontov, A. V. Parhomenko (KSS of the Pulkovo Observatory), R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias), D. Buckley (SAAO), R. Podesta, C. Lopez, C. Francile, F. Podesta (OOAFA, SJNU), H. Levato (ICATE, SJNU), V. Shumkov
MASTER Global Robotic Net (Lipunov et al., 2010, Advances in Astronomy,vol.2010, 30L) observed extremaly bright (3.7062e-04 erg/cm^2, Ttrig=2019-05-30 10:19:08.9UT, Bissaldi et al. GCN #24692) Fermi GRB 190530A (GBM team GCN #24676, BALROG Biltzinger et al.GCN #24677, LAT Longo et al. GCN #24679 and IPN localization; gamma-ray transient also detected by AGILE 8s later Lecarelli et al. GCN #24678, Verrecchia et al. GCN #24683) by MASTER-Amur, MASTER-Tunka, MASTER-SAAO, MASTER-Kislovodsk, MASTER-Tavrida, MASTER-IAC (Lipunov et al. GCN #24680, GCN #24693).
MASTER auto-detection system discovered GRB optical counterpart MASTER OT J080207.73+352847.7 = AT 2019gdw at (RA,Dec2000)=08h 02m 07.73s +35d 28m 47.7s ( Lipunov et al. GCN #24680) with m_OT=16.7 ( W=0.2B+0.8R calibrated by thousands USNO-B1 stars) at 2019-05-30 18:12:10UT.
MASTER-Amur robotic telescope automatically was pointed to the Fermi GRB190530A BALROG localization at 2019-05-30 14:34:09 (error-box altitude = 13 deg., sun_alt=-17deg. very cloudy weather at sunset) with automatic photometry m_OT ~ 14.8
MASTER-Tunka robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 14:43:13UT (error_box_alt=26deg., sun_alt=-10deg.), automatic photometry m_OT ~ 16.5
MASTER-SAAO robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 16:34:41UT (very cloudy all horizont, error-box_alt=13.5 and go down, sun_alt=-11) mlim=14.5
MASTER-Kislovodsk robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 18:12:10 (sun altitute= -16deg., alert_altitute=23deg.) automatic photometry m_OT~16.7
MASTER-Tavrida robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 2019-05-30 18:12:17 (sun altitute= -8deg., alert_altitute=34deg.) automatic photometry m_OT~16.7
MASTER-IAC robotic telescope automatically was pointed to the GRB190530A at 2019-05-30 20:50:32UT (sun altitute=-11 deg., alert_altitute=36 deg.) automatic photometry m_OT~17.4
The covered map by MASTER and OT position are available at https://master.sai.msu.ru/site/master2/event.php?id=1034468
The optical counterpart was also detected by OSN (Kann et al. GCN #24684), NOT (Heintz et al. GCN #24686), OAJ (Izzo et al. GCN #24687), GWAC-F30 (Xin et al. GCN #24688), COATLI (Watson et al. GCN #24690).
The X-ray counterpart was detected by Swift (Melandri et al. GCN #24689).
Specroscopy: NOT (Heintz et al. GCN #24686) infered an upper limit on the redshift of z < 2.2
GCN Circular #24694
P. Ghumatkar, V. Sharma, D. Bhattacharya, T. Khanam and A. Vibhute (IUCAA), V. Bhalerao (IIT-B), 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 190530A, which was also detected by AGILE-MCAL (Lucarelli F. et al., GCN # 24678), Fermi-LAT (Longo F. et al., GCN # 24679), AGILE/GRID (Verrecchia F. et al., GCN # 24683), Swift-XRT (Melandri A. et al., GCN # 24689) and Fermi GBM (Bissaldi E. et al., GCN # 24692).
The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple pulses of emission with the strongest peak at 10:19:25.5 UT. The measured peak count rate associated with the burst is 2745 cts/s above the background in the combined data of four quadrants, with a total of 23800 cts. The local mean background count rate was 486 cts/s. Using cumulative rates, we measure a T90 of 23.9 s. In preliminary analysis, we find that 1931 Compton events are associated with this event.
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.
GCN Circular #24697
L. P. Xin, J. B. Zhang, G. W. Li, R. S. Zhang, T. C. Zheng, J. Wang, J. Y. Wei, Y. G. Yang, E. W. Liang, X. G. Wang, H. L. Li, X. H. Han, X. M. Lu, L. Huang, H. B. Cai, Y. L. Qiu, Y. Xu, Y. J. Xiao, Y. T. Zheng, C. Wu, J. S. Deng, D. W. Xu, D. Turpin, W. L. Dong, P. P. Zhang and Jirong Mao report:
We observed Fermi GRB 190530A (Fermi GBM Team, GCN Circ. 24676; Longo et al., GCN Circ. 24679) using the Xinglong-2.16m equipped with the BFOSC camera. Observations were carried out from 12:49:45 to 13:40:10 UT on 2019-05-31, 62*50sec R band images were obtained.
The optical afterglow (Lipunov et al., GCN 24680, 24693; Kann et al., GCN Circ 24684; Melandri et al., GCN Circ. 24689; Heintz et al., GCN Circ 24686; Lzzo et al., GCN Circ 24687; Xin et al., GCN Circ 24688; Watson et al., GCN Circ.24690) was clearly detected in our stacked image with a magnitude of R=19.63+/-0.1 mag at the mid time of about 1.12 days after the burst, calibrated with nearby SDSS stars
GCN Circular #24698
S. Belkin (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), V.R. Ayvazian (AbAO), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of larger IKI GRB FuN collaboration:
We observed the optical afterglow (Lipunov et al., GCN 24680, 24693; Kann et al., GCN 24684; Melandri et al., GCN 24689; Heintz et al., GCN 24686; Lzzo et al., GCN 24687; Xin et al., GCN 24688; Watson et al., GCN 24690; Xin et al., GCN 24697) of the Fermi GBM, LAT GRB 190530A (Fermi GBM Team, GCN 24676; Longo et al., GCN 24679) with AS-32 (0.7m) telescope of Abastumani Observatory starting on May 31 (UT) 17:44:00. Preliminary photometry of the afterglow is following.
```
Date        UT start t-T0   Filter Exp.  OT    Err. UL
                     (mid, days) (s)

2019-05-31  17:44:00 1.32171 R     19*60 18.5  0.1  19.5
```
The photometry is based on nearby USNO-B1.0 stars
```
USNO-B1.0_id R2
1255-0157926 13.35
1254-0159410 12.63
1255-0157793 13.56
```
GCN Circular #24700
D. A. Kann, L. Izzo (both HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), M. Blazek, C. C. Thoene, K. Bensch (all HETH/IAA-CSIC), and V. Casanova (IAA-CSIC) report:
We observed the afterglow position (Lipunov et al., GCN 24680) of the extremely bright GRB 190530A (GBM detection and localization: Fermi GBM team, GCN 24676, Biltzinger et al., GCN 24677; Fermi-LAT localization: Longo et al., GCN 24679; Agile-MCAL/GRID detections: Lucarelli et al., GCN 24678, Verecchia et al., GCN 24683) a second time with the 1.5-m telescope of the Sierra Nevada Observatory (OSN), Spain. The afterglow is now only marginally detected in single frames, so we stack 7 x 120 s images.
We measure the following AB magnitude:
Rc = 20.60 +- 0.15 mag at 1.44509 days after the GRB.
The magnitude was derived against 1 nearby star from the SDSS catalog, using the transformation equations of Lupton (2005), and transformed back into AB mag.
This magnitude is significantly fainter than expected from an extrapolation of the decay from the first day, indicating a break in the light curve must have occurred. Using other observations (Lipunov et al., GCN 24680, GCN 24693; Kann et al., GCN 24684; Heintz et al., GCN 24686; Izzo et al., GCN 24687; Xin et al., GCN 24688; Watson et al., GCN 24690; Xin et al., GCN 24697) we find the afterglow is described by a broken power-law with pre-break decay slope alpha_1 = 1.21 +/- 0.07, post-break decay slope alpha_2 = 3.75 +/- 0.40, and break time t_b = 0.78 +/- 0.06 days.
The steeper slope mentioned by Watson et al. (GCN 24690) may indicate the break was occurring during the COATLI observations. We note the magnitude given by Belkin et al. (GCN 2469 is significantly too bright, this may stem from their use of USNO stars as standard stars.
The post-break decay slope is extremely steep and generally not expected from the forward shock model and a typical electron energy distribution. Further observations are highly encouraged.
GCN Circular #24703
M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 190530A 33.8 ks after the LAT trigger (GCN Circ. 24676). A fading source consistent with the optical counterpart first reported by Lipunov et al. (GCN Circ. 24680) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
   RA  (J2000) =  08:02:07.70 = 120.53209 (deg.)
   Dec (J2000) = +35:28:46.8  =  35.47968 (deg.)
```
with an estimated uncertainty of 0.49 arc sec. (radius, 90% confidence).
Preliminary detections 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

v                56532        56734          199         18.49 +/- 0.23
b                38334        38490          153         18.06 +/- 0.09
u                38132        38329          194         17.09 +/- 0.06
w1               37734        38128          388         16.89 +/- 0.06
w2               44276        44610          329         17.39 +/- 0.08
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #24708
Moskvitin A. S. and Uklein R. I. (SAO RAS) report on behalf of larger collaboration.
We observed the field of the GRB 190530A (Fermi GBM Team, GCNC 24676; Longo et al., GCNC 24679) with the 1-m telescope of SAO RAS equipped with the MMPP (Multi-Mode Photometer-Polarimeter) and UBVRcIc filters on May 31 / June 1 night.
We obtained 11 x 300 sec. frames in Rc band. The OT (Lipunov et al., GCNC 24680; Kann et al., GCNC 24684; Heintz et al., GCNC 24686; Izzo et al., GCNC 24687; Xin et al., GCNC 24688; Watson et al., GCNC 24690; Lipunov et al., GCNC 24693; Xin et al., GCNC 24697; Belkin et al., GCNC 24698; Kann et al., GCNC 24700; Siegel, GCNC 24703) is clearly detected in our stacked image. The OT brightness is R(AB) = 19.39 +/- 0.05 (T_mid - T0 = 1.353 days).
The OT magnitude was calculated against the nearby SDSS stars whose magnitudes were transformed with the equations of Lupton (2005). The magnitude of OT was converted to AB system and was not corrected for the Galactic extinction.
GCN Circular #24709
J. Vinko, R. Szakats, A. Pal, L. Kriskovics, A. Ordasi, K. Sarneczky (MTA CSFK Konkoly Observatory) report:
The optical afterglow (Lipunov et al., GCN 24680; Kann et al., GCN 24684; Heintz et al., GCN 24686; Izzo et al., GCN 24687; Xin et al., GCN 24688; Watson et al., GCN 24690; Lipunov et al., GCN 24693; Xin et al., GCN 24697; Belkin et al., GCN 24698; Kann et al., GCN 24700; Siegel, GCN 24703; Moskvitin and Uklein, GCN 24708) of the bright GRB 190530A (Fermi GBM team, GCN 24676, Biltzinger et al., GCN 24677; Longo et al., GCN 24679; Lucarelli et al.,GCN 24678, Verecchia et al., GCN 24683) is marginally detected on the stacked Sloan-r band CCD frames (total exposure time 45 min) taken with the 0.8m RC80 telescope at Konkoly Observatory, Piszkesteto (Hungary) on 2019-05-31.35 UT, 1.42 day after the burst.
Aperture photometry on the stacked frame, tied to PS1 r-band data of 19 local comparison stars resulted in the following AB magnitude for the transient:
r_PS1 (AB) = 19.86 +/- 0.37 mag
This is consistent with R-band brightness (~19.39 +/- 0.05 AB-mag at 1.353 days after burst) reported by Moskvitin and Uklein (GCN 24708), but significantly brighter than the one measured by Kann et al. (GCN 24700, Rc ~ 20.60 +/- 0.15 AB-mag at 1.44509 day after burst).
Further monitoring of this interesting transient is encouraged.
GCN Circular #24712
S. Belkin (IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI), V.R. Ayvazian (AbAO), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI GRB FuN collaboration:
We continue observations the optical afterglow (Lipunov et al., GCN 24680, 24693 and also e.g. Kann et al., GCN 24684; Melandri et al., GCN 24689; Heintz et al., GCN 24686; Lzzo et al., GCN 24687; Xin et al., GCN 24688; Watson et al., GCN 24690; Xin et al., GCN 24697) of the Fermi GRB 190530A (Fermi GBM Team, GCN 24676; Longo et al., GCN 24679) with AZT-33IK telescope of Sayan observatory (Mondy) and AS-32 (0.7m) telescope of Abastumani Observatory. The afterglow is clearly visible in stacked images. Preliminary photometry of the afterglow is following.
```
Date        UT start t-T0   Filter Exp.   OT    Err. UL
                      (mid, days) (s)

2019-06-01  15:35:00 2.23638  R    29*60 19.62  0.07  21.2
2019-06-01  17:38:57 2.31769  R    30*60 19.70  0.14  20.6
```
The photometry is based on the nearby USNO-B1.0 stars
```
USNO-B1.0_id R2
1255-0157926 13.35
1254-0159410 12.63
1255-0157793 13.56
```
The photometry might be influenced by nearby optical source presented in Pan-STARRS DR1 catalog (ID 150571205309266249) mentioned in (Lipunov et al., GCN 24680).
GCN Circular #24714
Q. B. Yi, S. Xiao, Q. Luo, C. Cai, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team:
At 2019-05-30T10:19:08.90 (T0), Insight-HXMT/HE detected GRB 190530A (trigger ID: HEB190530429) in a routine search of the data, which was also triggered by Fermi/GBM (GCN #24676), Fermi/LAT (GCN #24679), and AGILE/MCAL(GCN #24678).
The Insight-HXMT/HE light curve mainly consists of multiple pulses with a duration (T90) of 20.31 s measured from T0+2.11 s. The 1-ms peak rate, measured from T0+10.52 s, is 18182 cnts/sec. The total counts from this burst is 214189 counts. Some part of the Insight-HXMT/HE light curve suffers data saturation due to the extreme brightness of this burst. URL_LC: http://www.hxmt.org/images/GRB/HEB190530429_lc.jpg
All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope.
Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org.
GCN Circular #24715
D. Frederiks, S. Golenetskii, R.Aptekar, A. Kozlova, A.Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The extremely bright, long GRB 190530A (Fermi GBM detection: GCN 24676,24692; AGILE-MCAL detection: GCN 24679; Fermi-LAT detection: GCN 24679; AGILE/GRID analysis: GCN 24683; AstroSat CZTI detection: GCN 24694) triggered Konus-Wind (KW) at T0=37146.000 s UT (10:19:06.000).
The light curve of the burst shows a bright, multi-peaked pulse with a total duration of ~55s, followed by a weaker and softer emission tail visible until ~T0+150 s. The emission in the bright phase of the burst is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB190530_T37146/
As observed by Konus-Wind, the burst had a fluence of (5.57 � 0.15)x10^-4 erg/cm2 and a 64-ms peak energy flux, measured from T0+14.912, of (1.59 � 0.10)x10^-4 erg/cm2 (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+44.228 s) is best fit in the 20 keV - 16 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.03 (-0.02,+0.02), the high energy photon index beta = -3.03 (-0.36,+0.22), the peak energy Ep = 848 (-33,+44) keV, chi2 = 140/96 dof.
The spectrum near the peak count rate (measured from T0+14.848 s to T0+15.104 s) is best fit in the 20 keV - 16 MeV range by a cutoff power-law (CPL) function with the following model parameters: the photon index alpha = -0.41(-0.07,+0.07), and the peak energy Ep = 1176(-46,+47) keV, chi2 = 55/60 dof. Fitting this spectrum with the GRB (Band) function yields the same alpha and Ep, and an upper limit on beta of -3.2.
Assuming an upper limit on the burst redshift z<2.2 (Heintz et al., GCN 24686) and a standard cosmology with H_0 = 70 km/s/Mpc, Omega_M = 0.30, and Omega_Lambda = 0.70, we estimate the following upper limits on the GRB rest-frame energetics: the isotropic energy release E_iso < 6.4x10^54 erg and the peak luminosity L_iso < 5.8x10^54 erg/s (both in the bolometric 1-10000 keV range). Location of GRB 190530A in rest-frame hardness-intensity planes, along with 'Amati' and 'Yonetoku' relations for the KW sample of GRBs with known redshifts (Tsvetkova et al., ApJ 850 161, 2017), can be found at http://www.ioffe.ru/LEA/GRBs/GRB190530_T37146/GRB190530A.pdf
All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.
GCN Circular #24729
Brajesh Kumar (IIA), Avinash Singh (IIA), G. C. Anupama (IIA), D. K. Sahu (IIA) and S. B. Pandey (ARIES)
We observed the field of GRB 190530A (Fermi GBM team, GCN 24676, Biltzinger et al., GCN 24677; Lucarelli et al.,GCN 24678, Longo et al., GCN 24679; Verecchia et al., GCN 24683) with the 2-m Himalayan Chandra Telescope (HCT) located at the Indian Astronomical Observatory, Hanle, India. The observations started on 2019-06-02 14:50:43 UT i.e. around 3.19 days from Fermi GBM trigger (GCN 24676).
The optical afterglow (Lipunov et al., GCN 24680; Kann et al., GCN 24684; Heintz et al., GCN 24686; Izzo et al., GCN 24687; Xin et al., GCN 24688; Watson et al., GCN 24690; Lipunov et al., GCN 24693; Xin et al., GCN 24697; Belkin et al., GCN 24698; Kann et al., GCN 24700; Siegel, GCN 24703; Moskvitin and Uklein, GCN 24708; Vinko et al., GCN 24709; Belkin et al., GCN 24712) is detectable in our stacked image taken in Bessell R-band with a total integration time of 15 min. The preliminary magnitude of the OT is estimated as 21.3 +/- 0.3 mag.
These magnitudes were calibrated using the field stars from the USNO-B1.0 catalogue.
We thank the observing staff at IAO and CREST for helping with the observations.
GCN Circular #24745
D. Nandi, Abhinand V, H. Kumar, M. Khandagale, V. Bhalerao(IITB), G. C. Anupama, J. Stanzin (IIA) report on behalf of the GROWTH collaboration:
We observed the field of GRB190530A reported by Fermi GBM Team (GCN 24676) at 2019-06-01.635 and 2019-06-02.685 UT with the 0.7m GROWTH-India telescope. The images were taken in r filter. We detect a very faint source at position Ra: 08h 02m 07.73s, Dec: +35d 28m 47.7s. Photometric results obtained are as follow:-
```
------------------------------------------------------------------

 MJD(Start)| Exposure(s) | Stacked   | Filter | Mag | Magerr |

------------------------------------------------------------------

58635.636 | 600  | No | r | 20.118 | 0.14 |

58636.685  | 5*500 | YES | r | 20.48 | 0.11 |

------------------------------------------------------------------
```
Magnitudes are calibrated with panstarrs in the same field. Photometric results are found to be in agreement with (Lipunov et al., GCN 24680; Kann et al., GCN 24684; Heintz et al., GCN 24686; Izzo et al., GCN 24687; Xin et al., GCN 24688; Watson et al., GCN 24690; Lipunov et al., GCN 24693; Xin et al., GCN 24697; Belkin et al., GCN 24698; Kann et al., GCN 24700;Vinko et al., GCN 24709; Siegel, GCN 24703; Moskvitin and Uklein, GCN 24708; Belkin et al., GCN 24712; Brajesh et al., GCN 24729). Using data of above-mentioned GCNs along with GIT data, we found that source is fading with a power law index of 1.52.
The fitted curve can be found here:
https://lh5.googleusercontent.com/uyI9IhOx5bbe7_Ii-eHWsaj7r2Qw1g10_Lb_HIWKd5YBp8xsYC1OCPhdvYGifF80tkEgfWI-SMZl5RqgyRisuJS4mt3tHAIBEwoyVRJwX3B2LtsjVx1V=w572
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA).
GCN Circular #24751
J. Vinko, R. Szakats, A. Pal, L. Kriskovics, A. Ordasi, K. Sarneczky (MTA CSFK Konkoly Observatory) report:
We took follow-up observations on the optical afterglow (Lipunov et al., GCN 24680; Kann et al., GCN 24684; Heintz et al., GCN 24686; Izzo et al., GCN 24687; Xin et al., GCN 24688; Watson et al., GCN 24690; Lipunov et al., GCN 24693; Xin et al., GCN 24697; Belkin et al., GCN 24698; Kann et al., GCN 24700; Siegel, GCN 24703; Moskvitin and Uklein, GCN 24708; Vinko et al., GCN 24709; Belkin et al., GCN 24712; Kumar et al., GCN 24729; Nandi et al., GCN 24745) of the bright GRB 190530A (Fermi GBM team, GCN 24676, Biltzinger et al., GCN 24677; Longo et al., GCN 24679; Lucarelli et al.,GCN 24678, Verecchia et al., GCN 24683).
The source was clearly detected on the stacked Sloan-r band CCD frames (total exposure time 60 min) taken with the 0.8m RC80 telescope at Konkoly Observatory, Piszkesteto (Hungary) on 2019-06-01.85 UT, but only marginally detected on the frames taken on 2019-06-02.86 UT (2.42 and 3.43 days after burst, respectively).
We measured the brightness of the transient via aperture photometry on the stacked r-band frames using PS1 r-band magnitudes of 19 local comparison stars. The results, corrected for the contamination of the nearby faint source (r_PS1(AB) = 20.947 +/- 0.0565 mag), are as follows:
```
# Date      UT(mid)    JD-2400000     r(AB)  unc.   Ref
#----------------------------------------------------------------
2019-05-31 20:23:35   58635.349711    20.36  0.37   GCN 24709
2019-06-01 20:23:56   58636.349953    20.15  0.11   this circular
2019-06-02 20:37:30   58637.359375    22.10  0.41   this circular
#----------------------------------------------------------------
```
Note that in Vinko et al. (GCN 24709) the UT date of the observation was reported incorrectly. The correct date was 2019-05-31.85 UT. Also, our previous photometry given in GCN 24709 was not corrected for the nearby contaminating source. The table above contains the updated, corrected magnitudes.
Our last photometric measurement (taken on 2019-06-02) is consistent with the R-band magnitude reported by Kumar et al. (GCN 24729, R ~ 21.3 +/- 0.3 mag).
GCN Circular #24763
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), L. Izzo, M. Blazek, C. C. Thoene, K. Bensch (all HETH/IAA-CSIC) report:
We checked the magnitude of our second-epoch OSN observation (Kann et al., GCN 24700) of the Fermi GBM/LAT GRB 190530A (Fermi GBM team, GCN 24676; Longo et al., GCN 24679) and found a calculation error which resulted in an incorrect zero-point. Remeasuring the magnitude against four SDSS stars (once again transformed to Rc via the equations of Lupton 2005) we now derive Rc(AB) = 19.51 +/- 0.04 mag. This is in good agreement with the value obtained by Moskvitin & Uklein (GCN 24708). The magnitude of Belkin et al. (GCN 24698) is still overly bright compared to our new result, and the revised value from Vinko et al. (GCN 24751) is now significantly fainter.
We obtained 7 x 300 s images in SDSS r' with the 0.8m telescope of the Observatorio Astrofisico de Javalambre (Teruel, Spain). The first three images were taken too early in twilight and were discarded. The afterglow is clearly detected in the stack of the four last images, and we measure:
r'(AB) = 20.27 +/- 0.06 mag at 2.43735 days after the GRB.
This is in good agreement with an earlier value from Vinko et al. (GCN 24751) combined with a steep decay.
Using the further photometry published since Kann et al. (GCN 24700) (Moskvitin et al., GCN 24708; Belkin et al., GCN 24712; Kumar et al., GCN 24729; Nandi et al., GCN 24745; Vinko et al., GCN 24751) we find:
- The steep decay between the observation of Watson et al. (GCN 24690) and Xin et al. (GCN 24697) remains, and is not significantly affected by our revised OSN measurement.
- There may be a small flare at 1.4 days (this GCN [OSN]; Moskvitin et al., GCN 24708).
- Starting at 2.2 days (Belkin et al., GCN 24712; Vinko et al., GCN 24751; this GCN [OAJ]; Nandi et al., GCN 24745; Kumar et al., GCN 24729), yet another steep decay sets in, for which we measure alpha = 3.72 +/- 0.43. This value is perfectly in agreement with the one derived in Kann et al. (GCN 24700) at an earlier time, but now based on significantly more measurements.
Further follow-up is warranted, if possible.
GCN Circular #24978
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), M. Bremer (IRAM), S. Schulze (Weizmann), C. C. Thoene, D. A. Kann, L. Izzo, M. Blazek, K. Bensch (all HETH/IAA-CSIC), D. A. Perley (LJMU), S. Martin (ALMA), I. de Gregorio-Monsalvo (ESO), M. Michalowski (AOI-AMU), R. Sanchez-Ramirez (INAF-IAPS), D. B. Malesani (DTU Space) report:
We observed the field of the bright GRB 190530A (Fermi team GCN 24676) with NOEMA, at wavelengths between 76 and 150 GHz in 4 epochs, ranging between 31 May 2019, at 14:29 UT (1.17 days after the burst) and 15 June 2019, at 20:54 UT (16.44 days after the burst). The afterglow (discovered in the optical by Lipunov et al. GCN 24680) was detected on the first epoch with a flux density of 1.0 mJy at 92 GHz. At this time the peak frequency was located close to this observed frequency.
In the subsequent epochs the peak frequency of the synchrotron spectrum was bluewards of the 76 GHz frequency band and the source declined steadily in flux density until it was no longer detected in our latest observation, which had an r.m.s of 0.066 mJy at the 92 GHz band.

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Jochen Greiner, last update: 04-Jul-2019 [Disclaimer]