Gamma-ray Burst 180703A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 03 Jul 18 21:02:05 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     552344505
GRB_RA:           12.967d {+00h 51m 52s} (J2000),
                  13.141d {+00h 52m 34s} (current),
                  12.492d {+00h 49m 58s} (1950)
GRB_DEC:         -69.600d {-69d 35' 59"} (J2000),
                 -69.500d {-69d 29' 58"} (current),
                 -69.872d {-69d 52' 17"} (1950)
GRB_ERROR:       19.63 [deg radius, statistical plus systematic]
GRB_INTEN:       107 [cnts/sec]
DATA_SIGNIF:     7.80 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        18302 TJD;   184 DOY;   18/07/03
GRB_TIME:        75700.50 SOD {21:01:40.50} UT
GRB_PHI:         230.00 [deg]
GRB_THETA:        45.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.73
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   2%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 1,1,0, 0,0,0, 0,0,
SUN_POSTN:       102.91d {+06h 51m 40s}  +22.91d {+22d 54' 19"}
SUN_DIST:        111.30 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      346.20d {+23h 04m 49s}   -9.47d {-09d 27' 58"}
MOON_DIST:        62.48 [deg]
MOON_ILLUM:      74 [%]
GAL_COORDS:      302.88,-47.53 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      318.45,-63.01 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180703876/quicklook/glg_lc_medres34_bn180703876.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 166.37,22.78 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 03 Jul 18 21:02:14 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      58
TRIGGER_NUM:     552344505
GRB_RA:           30.483d {+02h 01m 56s} (J2000),
                  30.625d {+02h 02m 30s} (current),
                  30.100d {+02h 00m 24s} (1950)
GRB_DEC:         -61.250d {-61d 15' 00"} (J2000),
                 -61.161d {-61d 09' 40"} (current),
                 -61.490d {-61d 29' 24"} (1950)
GRB_ERROR:       4.70 [deg radius, statistical plus systematic]
GRB_INTEN:       680 [cnts/sec]
DATA_SIGNIF:     52.50 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        18302 TJD;   184 DOY;   18/07/03
GRB_TIME:        75700.50 SOD {21:01:40.50} UT
GRB_PHI:         236.98 [deg]
GRB_THETA:        35.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.60
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 1,1,0, 0,0,0, 0,0,
SUN_POSTN:       102.91d {+06h 51m 40s}  +22.91d {+22d 54' 19"}
SUN_DIST:        101.87 [deg]   Sun_angle= 4.8 [hr] (West of Sun)
MOON_POSTN:      346.20d {+23h 04m 49s}   -9.47d {-09d 27' 56"}
MOON_DIST:        61.06 [deg]
MOON_ILLUM:      74 [%]
GAL_COORDS:      288.63,-53.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      343.23,-64.35 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180703876/quicklook/glg_lc_medres34_bn180703876.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 166.37,22.78 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Tue 03 Jul 18 21:02:43 UT 
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    8091,   Sub_Num: 0
GRB_INTEN:      9.10 [sigma]   
GRB_TIME:       75699.82 SOD {21:01:39.82} UT
GRB_DATE:       18302 TJD;   184 DOY;   18/07/03
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=552344505). 
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2018-07/2018-07-03T21-01-39.7029-16784-11152-0.lc

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 04 Jul 18 01:10:37 UT
NOTICE_TYPE:     Fermi-LAT Offline Position
TRIGGER_NUM:     552344505
GRB_RA:            6.541d {+00h 26m 10s} (J2000),
                   6.750d {+00h 27m 00s} (current),
                   5.973d {+00h 23m 53s} (1950)
GRB_DEC:         -67.090d {-67d 05' 23"} (J2000),
                 -66.988d {-66d 59' 15"} (current),
                 -67.367d {-67d 22' 00"} (1950)
GRB_ERROR:       18.23 [arcmin radius, 90% containment, statistical only]
GRB_DATE:        18302 TJD;   184 DOY;   18/07/03
GRB_TIME:        75700.50 SOD {21:01:40.50} UT
TRIGGER_ID:      0x20000000    
MISC:            0x40000000
SUN_POSTN:       103.09d {+06h 52m 22s}  +22.89d {+22d 53' 26"}
SUN_DIST:        113.44 [deg]   Sun_angle= 6.4 [hr] (West of Sun)
MOON_POSTN:      348.20d {+23h 12m 49s}   -8.80d {-08d 47' 51"}
MOON_DIST:        59.53 [deg]
MOON_ILLUM:      72 [%]
GAL_COORDS:      306.74,-49.85 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      319.90,-59.63 [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 GRB180703A.
COMMENTS:        This source corresponds to GBM trigger.

GCN Circular #22882
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 180703A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00070
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 #22883
J. L. Racusin (NASA/GSFC), M. Crnogor=C4=8Devi=C4=87 (UMD), M. Axelsson (KTH and Stockholm Univ.),=20 A. Barker (George Washington), G. Vianello (Stanford), and M. Arimoto (Kanazawa University),=20 report on behalf of the Fermi-LAT team:
At 21:01:40.50 on July, 03, 2018 Fermi-LAT detected high-energy emission from GRB 180703A,=20 which was also detected by Fermi-GBM (trigger 552344505 / 180703876).
The best LAT on-ground location is found to be RA, Dec =3D 6.54, -67.1 (J2000) with an error radius of 0.3 deg (90% containment, statistical error only).
This was 48 deg from the LAT boresight at the time of the trigger.
The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally=20 correlated with the trigger with high significance.
The highest-energy photon is a ~930 MeV event which is observed at 40 seconds after the GBM trigger.
A Swift ToO has been approved 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 #22891
S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 180703A (Racusin et al. GCN Circ. 22883) in a series of observations tiled on the sky. The total exposure time is 2.0 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 863 s. The data were collected between T0+16.9 ks and T0+29.0 ks, and are entirely in Photon Counting (PC) mode.
One uncatalogued X-ray source has been detected, it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below:
Source 1:
```
  RA (J2000.0):  6.4693  =  00:25:52.63
  Dec (J2000.0): -67.1802  =  -67:10:48.7
  Error: 5.5 arcsec (radius, 90% conf.)
  Count-rate: 0.0207 [+0.0067, -0.0055] ct s^-1   
  Distance: 339 arcsec from Fermi/LAT position.
  Flux: (1.22 [+0.39, -0.32])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
A catalogued source was also detected.
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_GRB00070.
This circular is an official product of the Swift-XRT team.
GCN Circular #22892
C. Guidorzi, R. Martone (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara, D. Morris (U. of Virgin Islands) on behalf of a large collaboration report:
One of the LCO 1-m units at Sutherland Observatory (South Africa) began observing Fermi-LAT GRB 180703A (Racusin et al. GCN 22883) on July 04, 02:34 UT (5.5 hours after the GRB trigger time) with the SDSS i' filter. On the border of the Swift-XRT error circle of source S1 (Gibson et al. GCN 22891) we marginally detect an object at the following position:
```
RA(J2000)=  00:25:52.35
DEC(J2000)= -67:10:43.4
```
with an error radius of ~1" and a magnitude of i'=20.6 +- 0.3 at a mid time of 5.65 hours post GRB, as calibrated against nearby USNOB-UCAC4 stars.
GCN Circular #22896
S.Poolakkil and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
"At 21:01:40.50 UT on 03 July 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180703A (trigger 552344505 / 180703876), which was also detected by the Fermi LAT (Racusin et al. 2018, GCN 22883). The GBM on-ground location is consistent with the LAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 44 degrees.
The GBM light curve shows a single peak with a duration (T90) of about 20.2 s (50-300 keV). The time-averaged spectrum from T0-3.1 s to T0+25.6 s is best fit by a Band function with Epeak = 360 +/- 33 keV, alpha = -0.80 +/- 0.04 and beta = -1.95 +/- 0.08.
The event fluence (10-1000 keV) in this time interval is (2.001 +/- 0.043)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+3.52 s in the 10-1000 keV band is 11.1 +/- 0.25 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #22898
S.W.K. Emery (UCL-MSSL) and E. Sonbas (Adiyaman Univ.) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180703A 17269 s after the Fermi/LAT trigger (Racusin et al. GCN Circ. 22883). No optical afterglow consistent with the XRT position of the uncatalogued X-ray source, source 1 (Gibson et al. GCN Circ. 22891) or the position from LCO Sutherland (Guidorzi et al. GCN Circ. 22892) 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 exposures at the position of source 1 are:
```
Filter      T_start(s)   T_stop(s)      Exp(s)         Mag

b             17353         28862           47         >19.2
u             17323         28834          116         >19.5
uvw1          17269         28807          234         >19.8
uvw2          17384         28917           97         >19.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #22900
V. Sharma, A. Vibhute and D. Bhattacharya (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 180703A, which was also detected by Swift (Evans P. A. et al., GCN 22882), Fermi-LAT (Racusin J. L. et al., GCN 22883), Swift-XRT (Gibson S. L. et al., GCN 22891) and Fermi-GBM (Poolakkil S. et al., GCN 22896).
The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak of emission with peak at 21:01:44.5 UT, ~4 s after the GBM trigger. The measured peak count rate is 277.3 cts/s above the background in combined data of four quadrants, with a total of 2182 cts. The local mean background count rate was 519.6 cts/s. Using cumulative rates, we measure a T90 of 20.9 s.
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 #22925
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,
A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge 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 180703A (Fermi-LAT detection: Racusin et al., GCN Circ. 22883; Fermi-GBM detection: Poolakkil and Meegan, GCN Circ. 22896; AstroSat CZTI detection: Sharma et al., GCN Circ. 22900) was detected by Fermi (GBM trigger 552344505), Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), and Swift (BAT), at about 75700 s UT (21:01:40). The burst was outside the coded field of view of the BAT.
We have triangulated it to a Konus-HEND annulus centered at RA(2000)=312.437 deg (20h 49m 45s) Dec(2000)=-22.995 deg (-22d 59' 40"), whose radius is 54.738 +/- 1.217 deg (3 sigma).
The annulus is consistent with, but does not reduce the area of, the LAT position reported by Racusin et al. (GCN Circ. 22883).
A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB180703_T75705/IPN
GCN Circular #22926
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tiurina, A.Kuznetsov, V.Chazov, I. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov Lomonosov Moscow State University,SAI
D. Buckley, South African Astronomical Observatory (SAAO)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias (IAC)
A. Tlatov, V.Senik, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
R. Podesta, F. Podesta, C. Lopez, C.Francile Observatorio Astronomico Felix Aguilar (OAFA)
H.Levato, Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
O. Gres, N.M.Budnev , Yu.Ishmuhametova Irkutsk State University (ISU)
A. Gabovich, V. Yurkov, Yu. Sergienko Blagoveschensk Educational State University (BSPU) MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the GRB180703A (Poolakkil et al., GCN Circ #22896) 17 sec after notice time and 576 sec after trigger time at 2018-07-03 21:11:17 UT. On our first (120s exposure) set we not found optical transient within FERMI error-box (ra=349.946 dec=-65.5794 r=1.62) brighter then 18.0.
MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the GRB180703A (Racusin et al., GCN Circ #22883) 14961 sec after trigger time at 2018-07-04 01:11:02 UT . On our first (180s exposure) set we do not found optical transients within LAT error-box (ra=6.54 dec=-67.09 r=0.3) brighter then 18.3.
The observations made on zenit distance = 44 degrees, galaxy latitude b = -50 degree. The moon (72 % bright part) is 55 degrees above the horizon. The distance between moon and object is 60 The sun altitude is -55.4 degree. The object can be observed till sunrise at 2018-07-04 05:38:26
MASTER-OAFA robotic telescope (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 GRB180703A 14975 sec after trigger time at 2018-07-04 01:11:15 UT. On our first (180s exposure) set we found 6 optical transient within LAT error-box (ra=6.5375 dec=-67.0894 r=0.3039) brighter then 14.7.
The observations made on zenit distance = 76 degrees, galaxy latitude b = -50 degree. The moon (72 % bright part) below the horizon (The altitude of the Moon is -18 degree ). The sun altitude is -43.1 degree. The object can be observed till sunrise at 2018-07-04 11:36:37
The visibility GRB error box (coord: 349.9500 -65.5800 error_box: 0.3) at trigger time at different MASTER sites:
```
obj: -42.33 sun: -21.55 - Tavrida (Crimea, Russia) 
obj: -41.44 sun: -11.38 - IAC, Teide, (Tenerife, Spain)
obj:  28.43 sun: -66.35 - SAAO (Sutherland, SA) 
obj: -31.89 sun: -23.27 - Kislovodsk (Russia)
obj: -38.98 sun: -9.15 -  Ural(Kourovka, Russia)
obj: -27.62 sun:  0.11 -  Tunka (near Baykal Lake, Russia) 
obj: -26.46 sun: 12.65 -  Amur(Blagoveschensk)
obj:  7.39 sun:  7.00 -   OAFA (Argentina)
```
The message may be cited.
GCN Circular #22927
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 long GRB 180703A (IPN Triangulation: Hurley et al., GCN 22925; Fermi-LAT detection: Racusin et al., GCN 22883; Fermi-GBM detection: Poolakkil & Meegan, GCN 22896) triggered Konus-Wind at T0=3D75705.256 s UT (21:01:45.256)/
The burst light curve shows a single, FRED-like pulse with a total duration of ~50 s. Also, there is a weak count rate increase in the softest KW light curve around T0 + 170 s. The emission in the main peak is seen up to ~10 MeV.
As observed by Konus-Wind, the burst had a fluence of (4.1 =B1 1.0)x10^-5 erg/cm2 and a 64-ms peak energy flux, measured from T0+1.728, of (8.9 =B1 1.3)x10^-6 erg/cm2 (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+49.408 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 -0.85 (-0.21,+0.33), the high energy photon index beta =3D -1.89 (-0.37,+0.19), the peak energy Ep =3D 367 (-136,+196) keV, chi2 =3D 89/97 dof.
The spectrum near the peak count rate (measured from T0 to T0+8.448 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 -0.73 (-0.17,+0.20), the high energy photon index beta =3D -1.90 (-0.22,+0.13), the peak energy Ep =3D 407 (-97,+147) keV, chi2 =3D 88/97 dof.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180703_T75705/
All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.
GCN Circular #22931
S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has conducted further observations of the field of the Fermi/LAT-detected burst GRB 180703A (Racusin et al. GCN Circ. 22883). The observations now extend from T0+17.3 ks to T0+263.7 ks. The source previously reported by Gibson et al. (GCN Circ. 22891), "Source 1", is believed to be the afterglow. The position of this source is RA, Dec=6.4699, -67.1802 which is equivalent to:
```
RA (J2000): 00:25:52.79
Dec(J2000): -67:10:48.7
```
with an uncertainty of 4.8 arcsec (radius, 90% confidence). This position is 5.7 arcmin from the Fermi/LAT position. The source is fading with alpha >0.8.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020797. The results of the full analysis of the tiled XRT observations are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00070.
This circular is an official product of the Swift-XRT team.
GCN Circular #22944
C. Guidorzi, R. Martone (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara, D. Morris (U. of Virgin Islands) on behalf of a large collaboration report:
We observed Fermi-LAT GRB 180703A (Racusin et al. GCN 22883) with the LCO 2-m unit in Hawaii (former FTN) on July 12, 17:46 UT (8.9 days after the GRB trigger time) with the SDSS i' filter. We do not detect the optical candidate (Guidorzi et al. GCN 22892) found on the border of the Swift-XRT error circle of the confirmed X-ray afterglow (Gibson et al. GCN 22931) down to a limit magnitude of i'> 22.0 with a 5x120s exposure. We therefore confirm the nature of optical afterglow of the candidate. A comparison between the images taken at both epochs is available at the link below.
http://www.fe.infn.it/u/guidorzi/new_guidorzi_files/180703A_OT.png
GCN Circular #23889
L. Izzo (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC and DARK/NBI), P. Schady (U. Bath), D. B. Malesani (DAWN/NBI and DARK/NBI), D. A. Kann (HETH/IAA-CSIC), C. Kouveliotou (GWU), V. D’Elia (SSDC) and N. R. Tanvir (U. Leicester) report on behalf of the Stargate collaboration:
We have analysed the data obtained using the MUSE instrument, mounted on the ESO VLT UT4 (Yepun) telescope in Paranal, of the Fermi GRB 180703A (Racusin et al., GCN #22883; Poolakkil & Meegan, GCN #22896). MUSE is an integral-field-unit spectrograph which covers a field of view of up to ~1 arcmin**2. Our observations started on 2018 July 04 at 07:53:56 UT, 10.92 hr after the GRB detection, and consisted of four exposures of 250 s each.
When we integrate the data cube along the full MUSE wavelength range, we detect a source within the uncertainty of the Swift/XRT afterglow position (Gibson et al., GCN #22891), and consistent with the position of the reported optical counterpart (Guidorzi et al., GCN #22892, #22944). We extracted a spectrum of this source within the wavelength range 4750-9350 AA. The spectrum is noisy, and we cannot confirm continuum afterglow emission. However, we identify three strong emission lines which can be consistently interpreted as [O III] 4960,5008 AA and [O II] 3727/29 AA at a common redshift of z = 0.6678. Given the spatial coincidence with the optical counterpart, we propose that these features come from the GRB host galaxy and we conclude that this is the redshift of GRB 180703A.
We acknowledge support from the ESO observing staff in Paranal, in particular Andrea Mehner.

Back to JG's homepage

Jochen Greiner, last update: 12-Feb-2019 [Disclaimer]