Gamma-ray Burst 190919B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Thu 19 Sep 19 23:46:57 UT
NOTICE_TYPE:    INTEGRAL Wakeup
TRIGGER_NUM:    8377,   Sub_Num: 0
GRB_RA:         311.9090d {+20h 47m 38s} (J2000),
                312.2422d {+20h 48m 58s} (current),
                311.0613d {+20h 44m 15s} (1950)
GRB_DEC:        -44.7209d {-44d 43' 14"} (J2000),
                -44.6473d {-44d 38' 49"} (current),
                -44.9053d {-44d 54' 18"} (1950)
GRB_ERROR:      3.03 [arcmin, radius, statistical only]
GRB_INTEN:      10.11 [sigma]
GRB_TIME:       85611.27 SOD {23:46:51.27} UT
GRB_DATE:       18745 TJD;   262 DOY;   19/09/19
SC_RA:          301.84 [deg] (J2000)
SC_DEC:         -39.97 [deg] (J2000)
SUN_POSTN:      177.02d {+11h 48m 04s}   +1.29d {+01d 17' 34"}
SUN_DIST:       121.38 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:      60.11d {+04h 00m 27s}  +17.11d {+17d 06' 30"}
MOON_DIST:      114.55 [deg]
GAL_COORDS:     355.88,-38.90 [deg] galactic lon,lat of the burst
ECL_COORDS:     301.81,-25.80 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Time_Scale=10.0000 and Time_Error=10.0000.  
COMMENTS:       Possibly real GRB event

red DSS finding chart ps-file

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Thu 19 Sep 19 23:49:57 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    8377,   Sub_Num: 1
GRB_RA:         311.8881d {+20h 47m 33s} (J2000),
                312.2213d {+20h 48m 53s} (current),
                311.0404d {+20h 44m 10s} (1950)
GRB_DEC:        -44.7132d {-44d 42' 47"} (J2000),
                -44.6397d {-44d 38' 22"} (current),
                -44.8976d {-44d 53' 50"} (1950)
GRB_ERROR:      2.92 [arcmin, radius, statistical only]
GRB_INTEN:      11.34 [sigma]
GRB_TIME:       85627.58 SOD {23:47:07.58} UT
GRB_DATE:       18745 TJD;   262 DOY;   19/09/19
SC_RA:          301.84 [deg] (J2000)
SC_DEC:         -39.97 [deg] (J2000)
SUN_POSTN:      177.02d {+11h 48m 04s}   +1.29d {+01d 17' 31"}
SUN_DIST:       121.38 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:      60.14d {+04h 00m 34s}  +17.12d {+17d 06' 55"}
MOON_DIST:      114.58 [deg]
GAL_COORDS:     355.89,-38.88 [deg] galactic lon,lat of the burst
ECL_COORDS:     301.80,-25.79 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Time_Scale=0.3199 and Time_Error=8.0000.  
COMMENTS:       Possibly real GRB event

GCN Circ. 25787
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Integral GRB190919.99 (trigger No 8377,20h 48m 58.080s , -44d 38m 49.20s, R=0.0505) errorbox 26 sec after trigger time at 2019-09-19 23:47:17 UT, with upper limit up to 19.6 mag. The observations began at zenit distance = 24 deg. The sun altitude is -17.5 deg.
MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) was pointed to the Integral GRB190919.99 errorbox 32 sec after trigger time at 2019-09-19 23:47:23 UT, with upper limit up to 19.0 mag. The observations began at zenit distance = 77 deg. The sun altitude is -56.2 deg.
MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) was pointed to the Integral GRB190919.99 errorbox 54 sec after trigger time at 2019-09-19 23:47:45 UT, with upper limit up to 16.4 mag. The observations began at zenit distance = 50 deg. The sun altitude is -54.7 deg.
The galactic latitude b = -60 deg., longitude l = 98 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1142730
We obtain a following upper limits.

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      32 |         MASTER-OAFA |   C |    10 | 16.7 |        
      57 |         MASTER-OAFA |   C |    60 | 18.0 |  Coadd 
     342 |         MASTER-OAFA |   C |   630 | 19.6 |  Coadd 
      38 |          MASTER-IAC |  P| |    10 | 16.2 |        
      53 |          MASTER-IAC |  P| |    40 | 17.0 |  Coadd 
     308 |          MASTER-IAC |  P| |   550 | 19.0 |  Coadd 
      38 |          MASTER-IAC |  P- |    10 | 15.7 |        
      53 |          MASTER-IAC |  P- |    40 | 16.7 |  Coadd 
     368 |          MASTER-IAC |  P- |   670 | 18.1 |  Coadd 
      60 |         MASTER-SAAO |  P\ |    10 | 14.9 |        
      80 |         MASTER-SAAO |  P\ |    50 | 15.6 |  Coadd 
      66 |          MASTER-IAC |  P- |    10 | 15.6 |        
      66 |          MASTER-IAC |  P| |    10 | 16.1 |        
      86 |         MASTER-OAFA |   C |    20 | 17.1 |        
      90 |         MASTER-SAAO |  P\ |    20 | 15.1 |        
      99 |          MASTER-IAC |  P| |    20 | 16.7 |        
      99 |          MASTER-IAC |  P- |    20 | 16.1 |        
     126 |         MASTER-SAAO |  P\ |    20 | 15.1 |        
     143 |          MASTER-IAC |  P| |    30 | 16.8 |        
     188 |          MASTER-IAC |  P| |   120 | 17.8 |  Coadd 
     143 |          MASTER-IAC |  P- |    30 | 16.4 |        
     188 |          MASTER-IAC |  P- |   120 | 17.3 |  Coadd 
     150 |         MASTER-OAFA |   C |    30 | 17.5 |        
     173 |         MASTER-SAAO |  P\ |    30 | 15.4 |        
     218 |         MASTER-SAAO |  P\ |   120 | 16.2 |  Coadd 
     199 |          MASTER-IAC |  P- |    40 | 16.5 |        
     200 |          MASTER-IAC |  P| |    40 | 16.9 |        
     224 |         MASTER-SAAO |  P\ |    40 | 15.7 |        
     226 |         MASTER-OAFA |   C |    40 | 17.8 |        
     296 |         MASTER-OAFA |   C |   180 | 18.8 |  Coadd 
     264 |          MASTER-IAC |  P- |    50 | 16.6 |        
     264 |          MASTER-IAC |  P| |    50 | 17.2 |        
     284 |         MASTER-SAAO |  P\ |    50 | 15.7 |        
     317 |         MASTER-OAFA |   C |    60 | 18.0 |        
     337 |          MASTER-IAC |  P- |    60 | 16.7 |        
     427 |          MASTER-IAC |  P- |   240 | 17.7 |  Coadd 
     337 |          MASTER-IAC |  P| |    60 | 17.4 |        
     427 |          MASTER-IAC |  P| |   240 | 18.3 |  Coadd 
     355 |         MASTER-SAAO |  P\ |    60 | 16.0 |        
     445 |         MASTER-SAAO |  P\ |   240 | 16.4 |  Coadd 
     427 |          MASTER-IAC |  P- |    80 | 16.9 |        
     427 |          MASTER-IAC |  P| |    80 | 17.5 |        
     427 |         MASTER-OAFA |   C |    80 | 18.3 |        
     440 |         MASTER-SAAO |  P\ |    80 | 15.8 |        
     536 |          MASTER-IAC |  P| |   100 | 17.7 |        
     536 |          MASTER-IAC |  P- |   100 | 17.2 |        
     554 |         MASTER-SAAO |  P\ |   100 | 15.7 |        
     556 |         MASTER-OAFA |   C |   100 | 18.4 |        
     701 |         MASTER-OAFA |   C |   390 | 19.4 |  Coadd 
     665 |          MASTER-IAC |  P- |   120 | 17.2 |        
     830 |          MASTER-IAC |  P- |   450 | 17.9 |  Coadd 
     691 |         MASTER-SAAO |  P\ |   130 | 15.7 |        
     861 |         MASTER-SAAO |  P\ |   470 | 15.8 |  Coadd 
     711 |         MASTER-OAFA |   C |   130 | 18.5 |        
     819 |          MASTER-IAC |  P| |   150 | 18.0 |        
     999 |          MASTER-IAC |  P| |   510 | 18.0 |  Coadd 
     819 |          MASTER-IAC |  P- |   150 | 17.3 |        
     868 |         MASTER-SAAO |  P\ |   160 | 15.4 |        
     896 |         MASTER-OAFA |   C |   160 | 18.8 |        
    1006 |          MASTER-IAC |  P| |   180 | 17.9 |        
    1006 |          MASTER-IAC |  P- |   180 | 17.4 |        
    1056 |         MASTER-SAAO |  P\ |   180 | 14.6 |        
    1107 |         MASTER-OAFA |   C |   180 | 18.8 |        
    1287 |         MASTER-OAFA |   C |   540 | 19.5 |  Coadd 
    1251 |          MASTER-IAC |  P| |   180 | 18.1 |        
    1251 |          MASTER-IAC |  P- |   180 | 17.4 |        
    1431 |          MASTER-IAC |  P- |   540 | 18.0 |  Coadd 
    1280 |         MASTER-SAAO |  P\ |   180 | 15.3 |        
    1329 |         MASTER-OAFA |   C |   180 | 18.9 |        
    1490 |         MASTER-SAAO |  P\ |   180 | 15.1 |        
    1500 |          MASTER-IAC |  P| |   180 | 18.0 |        
    1680 |          MASTER-IAC |  P| |   540 | 18.6 |  Coadd 
    1500 |          MASTER-IAC |  P- |   180 | 17.4 |        
    1550 |         MASTER-OAFA |   C |   180 | 18.8 |        
    1717 |         MASTER-SAAO |  P\ |   180 | 15.4 |        
    1744 |          MASTER-IAC |  P| |   180 | 17.8 |        
    1744 |          MASTER-IAC |  P- |   180 | 17.2 |        
    1770 |         MASTER-OAFA |   C |   180 | 18.9 |        
    1950 |         MASTER-OAFA |   C |   540 | 19.6 |  Coadd 
    1928 |         MASTER-SAAO |  P\ |   180 | 15.3 |        
    1988 |         MASTER-OAFA |   C |   180 | 18.9 |        
    1990 |          MASTER-IAC |  P| |   180 | 17.8 |        
    1990 |          MASTER-IAC |  P- |   180 | 17.2 |        
    2170 |          MASTER-IAC |  P- |   540 | 17.8 |  Coadd 
    2156 |         MASTER-SAAO |  P\ |   180 | 15.7 |        
    2209 |         MASTER-OAFA |   C |   180 | 19.0 |        
    2240 |          MASTER-IAC |  P| |   180 | 17.8 |        
    2240 |          MASTER-IAC |  P- |   180 | 17.1 |        
    2387 |         MASTER-SAAO |  P\ |   180 | 15.7 |        
    2431 |         MASTER-OAFA |   C |   180 | 19.0 |        
    2489 |          MASTER-IAC |  P| |   180 | 17.8 |        
    2489 |          MASTER-IAC |  P- |   180 | 17.1 |        
    2652 |         MASTER-OAFA |   C |   180 | 19.0 |

Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.

GCN Circ. 25788
S.Mereghetti (INAF, IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC, Versoix) and J.Borkowski (CAMK, Torun) report:
a gamma ray burst lasting about 30 s has been detected by IBAS in the IBIS/ISGRI data at 23:46:40 UT of September 19, 2019.
The refined coordinates (J2000) are:
```
R.A.=  311.8862 deg
DEC.=  -44.7029 deg
```
with an uncertainty of 1.5 arcmin (90% c.l.).
The burst had a peak flux of 0.6 ph/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 3e-7 erg/cm2.
A plot of the light curve will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html
GCN Circ. 257889
J. Bolmer (MPE Garching) report:
We observed the field of GRB 190919B (INTEGRAL trigger 8377; Mereghetti et al. GCN 25788) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
Observations started at 23:50 UT on 19 September 2019, 3.6 min after the GRB trigger. They were performed at an average seeing of 1.31" and at an average airmass of 1.2. We detect the fading NIR afterglow at the following coordinates and with the following preliminary AB magnitudes at 407 +/- 194 s after the trigger:
Ra, Dec = 311.87765 -44.69533
```
J = 16.33 +/- 0.05,
H = 16.06 +/- 0.05,
Ks = 15.92 +/- 0.07.
```
Given magnitudes are calibrated against 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.10 mag in the direction of the burst (Schlafly & Finkbeiner 2011).

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Fri 20 Sep 19 06:20:26 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    8377,   Sub_Num: 2
GRB_RA:         311.8860d {+20h 47m 33s} (J2000),
                312.2192d {+20h 48m 53s} (current),
                311.0384d {+20h 44m 09s} (1950)
GRB_DEC:        -44.7027d {-44d 42' 09"} (J2000),
                -44.6292d {-44d 37' 44"} (current),
                -44.8871d {-44d 53' 12"} (1950)
GRB_ERROR:      1.50 [arcmin, radius, statistical only]
GRB_INTEN:      11.34 [sigma]
GRB_TIME:       85627.58 SOD {23:47:07.58} UT
GRB_DATE:       18745 TJD;   262 DOY;   19/09/19
SC_RA:          301.84 [deg] (J2000)
SC_DEC:         -39.97 [deg] (J2000)
SUN_POSTN:      177.26d {+11h 49m 02s}   +1.19d {+01d 11' 12"}
SUN_DIST:       121.15 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:      63.60d {+04h 14m 23s}  +17.99d {+17d 59' 08"}
MOON_DIST:      117.62 [deg]
GAL_COORDS:     355.90,-38.88 [deg] galactic lon,lat of the burst
ECL_COORDS:     301.80,-25.78 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Time_Scale=0.3199 and Time_Error=8.0000.  
COMMENTS:       refined_coordinates_after_offline_analysis

GCN Circular #25790
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the INTEGRAL GRB 190919B. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00020948
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 INTEGRAL 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 #25791
N.Tyurina, V. Lipunov, E. Gorbovskoy, V.Kornilov, F.Balakin, P.Balanutsa,A.Kuznetsov, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov,V.Senik, T.Pogrosheva, K.Pozdnyakov, A.Chasovnikov, V.Topolev, 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)
We see GRB190919B (INTEGRAL trigger 8377; Mereghetti et al. GCN 25788) at prompt and afterglow stage with flare (after 7 min) on several MASTER telescopes (Lipunov et al., GCN 25787) at GROND position (Bolmer et al, 25789).
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/event.php?id=1136619
The OT coordinates are:
RA, Dec = 20h 47m 30.56s , -44d 41m 42s.5 Error = 0.3 arcsec
The observation and reduction will be continued. The message may be cited.
GCN Circular #25792
G. Pugliese (Univ. Amsterdam), L. Izzo (DARK/NBI), J. Bolmer (MPE Garching), N. R. Tanvir (Univ Leicester), D. B. Malesani (DTU Space), D. Xu (NAO/CAS), D. A. Kann (HETH/IAA-CSIC), J. P. U. Fynbo (DAWN/NBI), report on behalf of the Stargate collabaration:
We observed the optical afterglow (Bolmer, GCN 25789) of the INTEGRAL GRB 190919B (Mereghetti et al., GCN 25788) using the ESO VLT UT2 (Kueyen) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-24700 AA, and consist of 4 exposures by 600 s each. The observation mid time was 2019 Sep 20.194 UT (4.87 hr after the GRB).
In a 30 s image taken with the acquisition camera on Sep 20.1714 UT, we detect the optical afterglow, for which we measure a magnitude r = 20.10 +- 0.02 AB (calibrated against nearby stars from the SkyMapper catalog; Wolf et al. 2018, PASA, 35, 010; https:doi.org/10.4225/41/593620ad5b574).
We clearly detect continuum over the full covered wavelength range. A wide trough is visible around 5130 AA, which we identify as due to H I. This is confirmed by the presence of the Ly alpha forest blueward of this wavelength. We also detect multiple, narrow absorption features across all the three arms, which we interpret as due to e.g. S II, Si II, O I, S IV, C IV, Fe II, Mg II, Ca I, at a common redshift z = 3.225.
We acknowledge excellent support from the ESO observing staff in Paranal, in particular Pedro Figueira, Nestor Jimenez, Camila Navarrete, and Juan Carlos Olivares.
GCN Circular #25793
A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo (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 INTEGRAL-detected burst GRB 190919B (Mereghetti et al. GCN Circ. 25788), collecting 3.0 ks of Photon Counting (PC) mode data between T0+28.6 ks and T0+36.4 ks.
An uncatalogued X-ray source has been detected 1.1 arcsec from the reported GROND afterglow position (Bolmer, GCN Circ. 25789):
Source 1:
```
  RA (J2000.0):  311.87783  =  20:47:30.68
  Dec (J2000.0): -44.69542  =  -44:41:43.5
  Error: 2.1 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0222 [+0.0032, -0.0031] ct s^-1   
  Distance: 0 arcsec from INTEGRAL position.
  Flux: (7.16 [+1.03, -0.98])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
The source is below the RASS limit and, due to the limited amount of data available so far, shows no signs of fading.
The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00020948.
This circular is an official product of the Swift-XRT team.
GCN Circular #25794
Martin Jelinek (ASU CAS Ondrejov, CZ), Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek, Michael Prouza (Institute of Physics, Prague, CZ) and Jan Strobl (ASU CAS Ondrejov, CZ)
report:
The 30 cm robotic telescope FRAM-Auger in Malargue (Argentina) reacted robotically to the INTEGRAL/IBAS alert of GRB190919B (Mereghetti et al., GCNC 25788), starting with a series of 20 s unfiltered images at 23:47:16 UT, i.e. 36 s post trigger.
We clearly detect the optical afterglow reported by Bolmer (GCN 25789), Tyurina et al. (GCN 25791) and Pugliese et al. (GCN 25792) at single frames. The optical lightcurve seems to have a multi-peak structure with maxima reaching r'(AB) ~ 16.5 mag, and fades beyond the single-image detection limit of r' ~ 17.2 by ~ 10 minutes post trigger. A detailed analysis is ongoing.
GCN Circular #25795
F. E. Marshall (NASA/GSFC) and A. Beardmore (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 190919B 28564 s after the INTEGRAL trigger (Mereghetti et al., GCN Circ. 25788). No optical afterglow consistent with the optical position (Bolmer, GCN Circ. 25789; Tyurina et al. GCN Circ. 25791) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

u_FC             28987        29196          206         >20.3
v                30258        36440          225         >19.6
b                29201        36022          301         >20.2
u                28987        35920          301         >20.7
w1               28564        35819          602         >20.8
m2               30471        30737          262         >20.3
w2               29416        36416         1204         >21.8
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #25796
R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:
We observed Fermi GRB 190919B (Mereghetti, GCN 25788) with the LCO 1-m Sinistro instrument on September 20, from 17:58 to 19:10 UT (corresponding to 18.27 to 19.47 hours from the GRB trigger time) with the SDSS i� and r� filters.
We performed a series of 28x30s exposures in each band. We do not detect the source in individual frames; however we detect a source in stacked images (at least 5 stacked images) that is not present in USNO-B1.0 or 2MASS surveys with the following magnitudes:
i = 20.60 +/- 0.14
r = 21.48 +/- 0.18
This flux measurement may be partially contaminated by the host galaxy, and it is calibrated against several USNO-B1.0 objects near the GRB location but is not corrected for Galactic Extinction.
Analysis is ongoing to determine if the source is fading over the course of the observations, and therefore likely the GRB afterglow.
These observations were possible thanks to the USVI NASA-EPSCoR Research Infrastructure Development (RID) grant NNX16AL44A.
GCN Circular #25798
Y.-D. Hu, E. Fernandez-Garcia and A. J. Castro-Tirado (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), S. Jeong and I. H. Park (SKKU) and M. D. Caballero-Garcia (ASU-CAS, CZ), I. Carrasco, C. Perez del Pulgar (Univ. de Malaga) and R. Querel (NIWA) on behalf of a larger collaboration, report:
The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded in 3.33 hrs to the INTEGRAL trigger of GRB190919B (Mereghetti et al., GCNC 25788). A series of unfiltered images were taken (60s exposure time). The optical source is detected at the position reported by Bolmer et al. (GCNC 25789) and Tyurina et al. (GCNC 25791) in the co-added image from which we derive a magnitude of 19.56 +/- 0.15 at median time of 4.41 h after the trigger.
Few hours later, the 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New Zealand) also automatically responded to this trigger and gathered a serie of unfiltered images (60s exposure time). The optical source still can be detected in the co-added image with a magnitude of f 21.2 +/- 0.4 at a median time of 9.54 hrs after trigger.
These results confirm the fading of the afterglow. The magnitude is calibrated against the USNO-B1 catalog and is not corrected for Galactic extinction in the direction of the GRB. Further observations are ongoing.
We thank the staff at both the Observatorio Astronomico Nacional in San Pedro Martir and NIWA Lauder for their excellent support.

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Jochen Greiner, last update: 21-Sep-2019 [Disclaimer]