GRB 230818A
GCN Circular 35506
Subject
GRB 230818A: further radio observations with the VLA
Date
2024-01-09T13:30:14Z (2 years ago)
From
Stefano Giarratana at University of Bologna <s.giarratana@ira.inaf.it>
Via
email
S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti
(INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),
N. Omodei (Stanford Univ.)
At 22:56:54 UT on 2023 September 18 (T_mid = 31.0 days post-burst)
and at 17:12:33 UT on 2023 November 28 (T_mid = 101.8 days
post-burst) the Karl G. Jansky VLA started observing the field of
GRB 230818A (Fermi GBM team, GCN 34478; Tohuvavohu et al.,
GCN 34479) at a central frequency of 6 and 10 GHz.
The standard J1331+3030 (3C286) was used as bandpass and
flux density calibrator, while J1912+3740 was used as complex
gain calibrator.
From a preliminary analysis, we do not detect the radio counterpart
of GRB 230818A. We derive the following upper limits (UL; 3sigma).
=====================================================
T_mid Freq UL r.m.s. Beam PA
[days] [GHz] [uJy] [uJy/b] [arcsec] [deg]
=====================================================
31.0 6 24 8 0.34x0.31 -64
31.0 10 24 8 0.22x0.19 -75
101.8 6 30 10 13.2x9.94 -87
101.8 10 24 8 9.05x6.06 -82
=====================================================
We would like to thank the staff of the VLA for approving, executing,
and processing the observations.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc.
These observations were carried out as part of project SF161095,
approved in the framework of the Fermi - NRAO joint program agreement.
GCN Circular 34641
Subject
GRB 230818A: radio observation with the VLA
Date
2023-09-08T13:08:24Z (2 years ago)
From
Stefano Giarratana at University of Bologna <s.giarratana@ira.inaf.it>
Via
email
S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti
(INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),
N. Omodei (Stanford Univ.)
At 23:33:30 UT on 2023 August 23 (T_mid = 5.02 days post-burst) the
Karl G. Jansky VLA observed the field of GRB 230818A (Fermi GBM
team, GCN 34478; Tohuvavohu et al., GCN 34479) at a central
frequency of 6 and 10 GHz.
The standard J1331+3030 was used as bandpass and flux density
calibrator, while J1912+3740 was used as phase calibrator.
From a preliminary analysis, we do not detect the radio counterpart
of GRB 230818A. The r.m.s. noise level of the images is
11 uJy/beam and 13 uJy/beam at 6 and 10 GHz, respectively.
The synthesized beams are 0.44 x 0.89 arcsec (PA: 81 deg) at 6 GHz
and 0.28 x 0.24 arcsec (PA: -70 deg) at 10 GHz.
We would like to thank the staff of the VLA for approving, executing,
and processing the observations.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc.
These observations were carried out as part of project SF161095,
approved in the framework of the Fermi - NRAO joint program agreement.
GCN Circular 34523
Subject
GRID detection of GRB 230818A
Date
2023-08-23T02:35:17Z (2 years ago)
From
GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>
Via
Web form
Chenyu Wang and Zirui Yang report on behalf of the GRID Collaboration:
The long-duration GRB 230818A (Fermi/GBM detection: GCN Circular 34478 and Swift/BAT detection: GCN Circular 34479 ) was observed with GRID-03B.
The detection was confirmed at the trigger time 2023-08-18T23:27:30 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 8.75 ± 1.63 seconds..
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.
GCN Circular 34515
Subject
GRB 230818A: Swift-BAT refined analysis
Date
2023-08-21T19:26:51Z (2 years ago)
From
Tyler Parsotan at NASA GSFC <tyler.parsotan@nasa.gov>
Via
email
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-60 to T+200 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230818A (trigger #1186032)
(Tohuvavohu, et al., GCN Circ. 34479). The BAT ground-calculated position is
RA, Dec = 285.888, 40.888 deg which is
RA(J2000) = 19h 03m 33.2s
Dec(J2000) = +40d 53' 16.5"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 32%.
The mask weighted light curve shows a single fast rise exponential decay peak.
T90 (15-350 keV) is 9.82 +- 1.25 sec (estimated error including systematics).
The time-averaged spectrum from T+0.07 to T+12.10 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.36 +- 0.10. The fluence in the 15-150 keV band is 1.9 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+1.59 sec in the 15-150 keV band
is 6.7 +- 0.5 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1186032/BA/ <http://gcn.gsfc.nasa.gov/notices_s/1186032/BA/>
GCN Circular 34511
Subject
Konus-Wind detection of GRB 230818A
Date
2023-08-21T15:16:55Z (2 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
legacy email
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long GRB 230818A (Swift detection: Tohuvavohu et al., GCN 34479;
Fermi GBM observation: Veres et al., GCN 34501)
triggered Konus-Wind (KW) at T0=84458.443 s UT (23:27:38.443).
The burst light curve shows a single FRED-like pulse
which starts at ~T0-0.256 s and has a duration of ~10 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230818_T84458/
As observed by Konus-Wind, the burst had
a total fluence of (4.91 ± 1.76)x10^-6 erg/cm^2 and
a 64-ms peak energy flux, measured from T0,
of (3.08 ± 0.90)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst (measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 15 MeV range by a power law with exponential
cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.00(-0.23,+0.27) and Ep = 251(-49,+81) keV (chi2 = 91/98 dof).
Fitting this spectrum by a Band function yields the same values of alpha and Ep,
and an upper limit on the high energy photon index beta of -2.5 (chi2 = 91/97 dof).
The spectrum near the peak count rate (measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 15 MeV range by a CPL model
with alpha = -0.40(-0.44,+0.56) and Ep = 259(-45,+64) keV (chi2 = 18/17 dof).
Fitting this spectrum by a Band function yields the same values of alpha and Ep,
and an upper limit on the high energy photon index beta of -2.7 (chi2 = 18/16 dof).
Assuming the redshift z=2.42 (Malesani et al., GCN 34485)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the burst isotropic energy release E_iso to (6.95 ± 2.49)x10^52 erg,
the isotropic peak luminosity L_iso to (1.49 ± 0.44)x10^53 erg/s,
the rest-frame peak energy of the time-integrated spectrum Ep,i,z to ~860 keV,
and the rest-frame peak energy at the peak of the emission Ep,p,z to ~890 keV.
With the obtained estimates, GRB 230818A is inside 90% prediction band for
the 'Amati' relation and inside 68% prediction band for the 'Yonetoku' relation
derived for the sample of >300 long KW GRBs with known redshifts
(Tsvetkova et al., 2017; Tsvetkova et al., 2021), see
http://www.ioffe.ru/LEA/GRBs/GRB230818_T84458/GRB230818A_rest_frame.pdf
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.
GCN Circular 34501
Subject
GRB 230818A: Fermi GBM Observation
Date
2023-08-20T18:27:14Z (2 years ago)
From
Cori Fletcher at USRA <cfletcher@usra.edu>
Via
Web form
P. Veres (UAH), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 23:27:35.37 UT on 18 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230818A (trigger 714094060/230818977).
which was also detected by Swift-BAT (A. Tohuvavohu et al. 2023, GCN 34479) and AstroSat (B. Pari et al. 2023, GCN 34492).
The Fermi GBM Final Real-time Localization (GCN 34478) is consistent with the Swift-BAT position.
The angle from the Fermi LAT boresight is 79 degrees.
The GBM light curve consists of a couple peaks with a duration (T90)
of about 10 s (50-300 keV). The time-averaged spectrum
from T0-1.5 to T0+13.8 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.02 +/- 0.06 and the cutoff energy,
parameterized as Epeak, is 260 +/- 30 keV.
The event fluence (10-1000 keV) in this time interval is
(5.6 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.58 s in the 10-1000 keV band is 10.2 +/- 0.3 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 34498
Subject
GRB 230818A: Nickel and KAIT telescope optical observations
Date
2023-08-19T22:13:43Z (2 years ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
legacy email
Neil Pichay, Elma Chuang, WeiKang Zheng and Alex Filippenko (UC Berkeley)
report on behalf of the KAIT GRB team:
We observed the field of GRB 230818A (Fermi GBM team, GCN 34478;
Tohuvavohu et al., GCN 34479) with the 1-m Nickel and 0.76-m KAIT
telescopes located at Lick observatory, California. Observations
started about 0.21 days after the burst. A total of 6 images (600s
exposure each) in R band were taken with Nickel telescopes, while
KAIT images were taken in clear band, with 60s exposure and coadded.
We detected the optical afterglow (Lipunov et al., GCNs 34476, 34477,
34481, 34482; Gompertz et al., GCN 34480; Moskvitin et al., GCN 34483;
Malesani et al., GCN 34485; Siegel and Tohuvavohu, GCN 34486; Pankov
et al., GCN 34487; Quadri and Strabla, GCN 34488; Klose et al., GCN
34491; Moskvitin et al., GCN 34495; 34497) and measure the following
magnitude calibrated to the Pan-STARRS1 catalog:
t-t0(days) filter mag err
0.218 clear 21.8 0.3
0.226 R 21.6 0.2
0.324 clear 21.3 0.3
GCN Circular 34497
Subject
GRB 230818A: SAO RAS 6-m telescope spectroscopy
Date
2023-08-19T20:52:59Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin, D. V. Oparin (SAO RAS), A. S. Pozanenko (IKI),
report on behalf of the larger GRB follow-up collaboration.
We observed the GRB 230818A OT (Lipunov et al., GCNs 34476, 34477,
34481, 34482; Gompertz et al., GCN 34480; Moskvitin et al., GCN 34483,
34495; Malesani et al., GCN 34485; Siegel and Tohuvavohu, GCN 34486;
Pankov et al., GCN 34487; Quadri and Strabla, GCN 34488;
Klose et al., GCN 34491) with the BTA 6-meter telescope of SAO RAS
equipped with Scorpio-II. The observations were started since ~ 0.5 h
after the burst (Fermi: GBM team, GCN 34478; Swift: Tohuvavohu et al.,
GCN 34479; AstroSat: Pari et al., GCN 34492).
In the 4 x 600 sec spectrum of (4200--8530 AA, FWHM resolution ~ 7A)
we identified the absorption lines (C IV, Si II) at a common redshift
of z = 2.42. We also identified Si IV and Al II lines at a common
redshift of 2.38 which might be an intervening system. Thus we confirm
the redshift measurement obtained by Malezani et al. (GCN 34485).
Using acquisition observation we obtained preliminary photometry
of the afterglow as following (calibrated against Pan-STARRS nearby
stars)
Date UT-start Exptime Filter t-T0 OT Err
sec days
2023-08-19 00:00:28 2 x 20 r' 0.02339 19.50 +/- 0.02
GCN Circular 34495
Subject
GRB 230818A: further SAO RAS Zeiss-1000 observations
Date
2023-08-19T19:35:54Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin (SAO RAS), V. P. Goranskij (SAI MSU),
report on behalf of the GRB follow-up team.
We observed the field of GRB 230818A (Fermi GBM team, GCN 34478;
Tohuvavohu et al., GCN 34479) with the 1-m telescope of SAO RAS
Zeiss-1000 equipped with the CCD photometer. We obtained
4 x 300 sec. images in Rc band on August 19, 17:42:30--18:07:26 UT.
The OT (Lipunov et al., GCNs 34476, 34477, 34481, 34482;
Gompertz et al., GCN 34480; Moskvitin et al., GCN 34483;
Malesani et al., GCN 34485; Siegel and Tohuvavohu, GCN 34486;
Pankov et al., GCN 34487; Quadri and Strabla, GCN 34488;
Klose et al., GCN 34491) is marginally detected with
the brightness of R = 23.0 +/- 0.3 (t_mid - t0 = 0.76903 days).
This preliminary photometry is based on nearby USNO-B1 stars (R2 mag).
The magnitude of the OT is not corrected for MW extinction.
GCN Circular 34493
Subject
GRB 230818A: AKO Upper Limit
Date
2023-08-19T17:53:39Z (2 years ago)
From
Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>
Via
legacy email
Mohammad Odeh, Osama Ghannam, Anas Mohammad, and Khalfan Al-Noaimy, report
on behalf of Al-Khatim Observatory (AKO) operated by the International
Astronomical Center in Abu Dhabi, UAE:
We observed the field of GRB 230818A (Lipunov et al., GCN 34476; Fermi: GBM
team, GCN 34478; Swift: Tohuvavohu et al., GCN 34479; Gompertz et al., GCN
34480; Moskvitin et al., GCN 34483; Malesani et al., GCN 34485; Siegel et
al., GCN 34486; Pankov et al., GCN 34487; Quadri et al., GCN 34488; Pavoni
et al., GCN 34490; Klose et al., GCN 34491) with our 0.36m f/7.7 robotic
telescope.
We obtained 13 x 180 sec. images in the clear filter on 19 August, from
16:05 to 17:23 UT, (t_mid - t0 = 17.3 hours) with an upper limit of
magnitude = 22.0 for the stacked frames.
We also obtained 15 x 180 sec. images in the Ic filter from 16:02 to 17:32
UT, (t_mid - t0 = 17.35 hours) with an upper limit of magnitude = 20.2 for
the stacked frames.
No reliable optical afterglow object was detected.
GCN Circular 34492
Subject
GRB 230818A: AstroSat CZTI detection
Date
2023-08-19T17:14:33Z (2 years ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
B. Pari (IITB), P. K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 230818A which was also detected by Fermi-GBM (Fermi GBM Team, GCN Circ. 34478) and Swift-BAT (Tohuvavohu et al., GCN Circ. 34479).
The source was detected in the 20-200 keV energy range in two quadrants. The light curve peaks at 2023-08-18 23:27:37.5 UTC. The measured peak count rate associated with the burst is 96.6 (+28.4, -24.9) counts/s above the background in the combined data of two quadrants, with a total of 372 (+89, -104) counts. The local mean background count rate was 198.2 (+2.1, -3.3) counts/s. Using cumulative rates, we measure a T90 of 6.3 (+2.1, -1.9) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-08-18 23:27:37.3 UTC. The measured peak count rate associated with the burst is 356.8 (+79.6, -44.8) counts/s above the background in the combined data of all quadrants, with a total of 2027 (+489, -526) counts. The local mean background count rate was 1569.3 (+11.3, -12.1) counts/s. We measure a T90 of 10.0 (+3.6, -4.3) s from the cumulative Veto light curve.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 34491
Subject
GRB 230818A: Tautenburg observations
Date
2023-08-19T16:59:54Z (2 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
Via
email
S. Klose, S. Melnikov, B. Stecklum, A. Nicuesa Guelbenzu, F. Ludwig (all TLS Tautenburg) report:
We observed the field of GRB 230818A (Fermi GBM team, GCN 34478; Tohuvavohu et al., GCN 34479) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6kx6k CCD camera and using the Sloan filter set.
For the optical transient discovered by Lipunov et al. (GCN 34476) we measure the following magnitudes:
g = 19.98 +/- 0.02 (midtime: August 19, 2023, 00:03:14 UT),
r = 19.76 +/- 0.02 (midtime: August 19, 2023, 00:14:43 UT),
i = 19.79 +/- 0.03 (midtime: August 19, 2023, 00:26:00 UT),
and
g = 21.35 +/- 0.12 (midtime: August 19, 2023, 01:57:48 UT),
r = 20.97 +/- 0.10 (midtime: August 19, 2023, 02:08:35 UT),
i = 20.86 +/- 0.10 (midtime: August 19, 2023, 02:19:32 UT),
calibrated against the Pan-STARRS catalog.
GCN Circular 34490
Subject
GRB 230818A: Leavitt Observatory upper limit
Date
2023-08-19T15:48:22Z (2 years ago)
From
leavittob@gmail.com
Via
Web form
E. Pavoni and L. Moretti (Leavitt Observatory), in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
We observed the field of GRB 230818A (Fermi: GBM team, GCN 34478; Swift: Tohuvavohu et al., GCN 34479; Gompertz et al., GCN 34480; Moskvitin et al., GCN 34483; Malesani et al., GCN 34485; Siegel et al., GCN 34486; Pankov et al., GCN 34487; Quadri et al., GCN 34488) with the telescope of Leavitt Observatory, Italy. Member of:
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
ATA - Associazione Tuscolana di Astronomia.
The observations began at 00:57 UT on 2023/08/18, 90 min after the GRB trigger, with our RC telescope D=250 mm F/D=8.
Weather conditions were good.
We took 32 images of 120 sec each. All images are V filtered, calibrated with master dark and master flat, stacked with ASTAP software.
We have not detected any clearly visible sources, up to 19.60 magnitude with clear sky at
RA (J2000): 19h 03m 33.08s
Dec (J2000): +40d 53' 48.0"
on a field of view 31.1 x 26.8 arcmin.
Start End Vlim
90 min 154 min 19.60
The magnitude limit was estimated with nearby stars from the Gaia EDR3 Catalog and is not corrected for galactic dust extinction.
The message may be cited.
GCN Circular 34489
Subject
GRB 230818A: Swift-XRT refined Analysis
Date
2023-08-19T15:19:55Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
S. Dichiara (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), A.P.
Beardmore (U. Leicester), J.P. Osborne (U. Leicester), E. Ambrosi
(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR)
and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.4 ks of XRT data for GRB 230818A, from 125 s to 40.1
ks after the BAT trigger. The data comprise 41 s in Windowed Timing
(WT) mode (the first 9 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode.
The light curve can be modelled with an initial power-law decay with an
index of alpha=2.2 (+0.5, -0.4), followed by a break at T+385 s to an
alpha of 0.76 (+/-0.06).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.96 (+0.21, -0.20). The
best-fitting absorption column is 1.8 (+/-0.7) x 10^21 cm^-2, in
excess of the Galactic value of 1.1 x 10^21 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 (4.7 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.8 (+/-0.7) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 1.8 sigma
Photon index: 1.96 (+0.21, -0.20)
If the light curve continues to decay with a power-law decay index of
0.76, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x
10^-13 (5.7 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01186032.
This circular is an official product of the Swift-XRT team.
GCN Circular 34488
Subject
GRB 230818A: Bassano Bresciano Observatory optical observations
Date
2023-08-19T14:56:53Z (2 years ago)
From
Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>
Via
legacy email
U.Quadri and L.Strabla (Bassano Bresciano Astronomical Observatory),
Members of:
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili-GRB.
GAC - Gruppo Astrofili Cremonesi.
We imaged the field of GRB 230818A detected by SWIFT(trigger 1186032)
with the robotic telescope of (IAU station 565) Bassano Bresciano
Observatory, Italy.
The observations started 13.61 min after the GRB trigger,
with our Newton automated telescope D=250 mm F/D=4.8.
Weather conditions were good.
We co-added 3 series of 10 exposures of 60 sec each.
We detected afterglow in the error box of the XRTcandidate.
(Fermi GBM team, GCN 34478; Tohuvavohu et al., GCN 34479;
Ben Gompertz et al., GCN 34480; V. Lipunov et al. GCN 34482;
A. S. Moskvitin et al., GCN 34483; D.B. Malesani et al., GCN 34485;
N. Pankov et al., GCN 34487) at the following position (+/- 2 arcsec):
RA (J2000.0) = 19 03 33.21
DEC(J2000.0) = +40 53 49.5
Our photometry of the afterglow are:
Date U.T. R mag Sigma
------------------------------------
2023 08 18.99405 18.90 0.07
2023 08 19.00126 19.21 0.07
2023 08 19.00154 19.47 0.06
----------------------------------
COMPARISON STARS
--------------------------------------------------------------------
pan-STARRS ID g r i Rc
--------------------------------------------------------------------
157072858562487290 17.4025 16.7800 16.5376 16.56
157052858895609613 16.8323 16.3279 16.1482 16.13
157072859081709765 15.0561 14.7054 14.5820 14.53
157092859169446573 16.9397 16.4745 16.2972 16.28
157102858906415897 17.0217 16.4894 16.2798 16.28
157062859601321798 15.7561 15.2872 15.0934 15.09
--------------------------------------------------------------------
Magnitudes were estimated with the Pan-STARRS cat.
Rc mag are derived using Lupton (2005) equations.
Not corrected for galactic dust extinction.
Reference:
http://www.osservatoriobassano.org/GRB.asp
The message may be cited.
GCN Circular 34487
Subject
GRB 230818A: KGO RC-25 optical observations
Date
2023-08-19T10:06:00Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
Via
legacy email
N. Pankov (HSE, IKI) A. V. Samokhvalov (citizen scientist, Surgut),
A. Pozanenko (IKI), S. Belkin (IKI, HSE) report on behalf of GRB IKI FuN:
We observed the field of GRB 230818A (Swift: Tohuvavohu et al., GCN 34479; Fermi: GBM team, GCN 34478) with 25cm telescope of KGO observatory. Observation started on 2023-08-18 23:42:15, i.e. 14.5 minutes after GRB trigger. The series consist of images with an exposure of 600 s in R-filter. WE clearly detect the afterglow (Lipunov et al., GCN 34476; Gompertz et al., GCN 34480; Moskvitin et al., GCN 34483; Malesani et al., GCN 34485; Siegel et al., GCN 34486). Preliminary photometry of images is following
Date UT-start Exptime Filter t-T0 OT Err UL
sec days
2023-08-18 23:42:15 1*600 R 0.013667 18.7 0.2 19.3
2023-08-18 23:52:24 6*600 R 0.038080 19.8 0.3 19.9
Ref.stars
PanSTARRS-DR1
RA Dec r i R(Lupton transformation)
19:03:22.0694 +40:55:31.814 14.1600 14.0074 13.97
19:04:17.2714 +40:50:28.744 14.8986 14.7352 14.71
GCN Circular 34486
Subject
GRB 230818A: Swift/UVOT Detection
Date
2023-08-19T07:46:57Z (2 years ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
Via
Web form
M. H. Siegel (PSU) and A. Tohuvavohu (U. Toronto)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230818A
144 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 34479).
A source consistent with the optical position (Lipunov et al., GCN
Circ. 34476) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 19:03:33.13 = 285.88806 (deg.)
Dec (J2000) = +40:53:49.0 = 40.89695 (deg.)
with an estimated uncertainty of 0.48 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits 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
white 144 294 147 19.09 +/- 0.07
v 379 572 39 18.40 +/- 0.30
b 477 1513 117 19.68 +/- 0.20
u 452 1487 117 >19.5
w1 428 1463 97 >20.2
w2 1026 4987 255 >20.1
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.101 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 34485
Subject
GRB 230818A: NOT photometry and spectroscopy
Date
2023-08-19T06:20:27Z (2 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Via
email
D.B. Malesani (Radboud and DAWN/NBI), D. Xu, S.Q. Jiang, T.H. Lu, Z.P. Zhu (NAOC), J.P.U Fynbo (DAWN/NBI), L. Izzo, (INAF-OACN & DAWN/NBI), Z. Gray (NOT) report:
We observed the optical counterpart (Lipunov et al., GCN 34476; Gompertz et al., GCN 34480) of GRB 230818A detected by Fermi/GBM (Fermi/GBM team, GCN 34478) and Swift/BAT (Tohuvavohu et al., GCN 34479), using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera.
Observations started at 23:53:33 UT on 2023-08-18, i.e., 26 min post-burst, and 2x1200 s spectra were obtained, with a spectral coverage of 3600 - 9500 AA.
The spectrum shows a trace throughout the whole range, with a broad absorption feature at ~ 4150 AA, which can be interpreted as Lya at z~2.4. Redward several prominent absorption features are present, which can be interpreted as due to Si II, O I, C II, Si IV, C IV, Ni II, Fe II at a common redshift of z = 2.42, being consistent with the Lya feature. We thus think this is the redshift of the burst.
After the spectroscopy, an 150 s exposure in the Sloan i-band was obtained. We measured m(i) = 20.02 +/- 0.02 at 1.21 hr post-burst, calibrated with nearby SDSS stars.
GCN Circular 34484
Subject
GRB 230818A: Enhanced Swift-XRT position
Date
2023-08-19T03:42:13Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1669 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 230818A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 285.88784, +40.89668 which is equivalent
to:
RA (J2000): 19h 03m 33.08s
Dec (J2000): +40d 53' 48.0"
with an uncertainty of 2.2 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
GCN Circular 34483
Subject
GRB 230818A: SAO RAS Zeiss-1000 observations
Date
2023-08-19T03:12:38Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin, D. V. Oparin, V. S. Shergin and
V. V. Komarov (SAO RAS), report on behalf of the GRB follow-up team.
We observed the field of GRB 230818A (Fermi GBM team, 34478;
Tohuvavohu et al., GCN 34479) with the 1-m telescope of SAO RAS
Zeiss-1000 equipped with the CCD photometer. We started observations
on August 18, 23:32:18 UT (~5 minutes after the trigger) and obtained
multiple images in BVRcIc bands (principally in Rc).
We clearly detected the OT (Lipunov et al., GCNs 34476, 34477,
34481, 34482; Gompertz et al., GCN 34480) in our individual
frames with the coordinates
R. A. (J2000) = 19:03:33.11
Decl. (J2000) = +40:53:49.2 (+/- 0".5)
and the following brightness:
UT_start exp, s t_mid-T0, h Rmag +/- err
23:32:18 60 0.0872 17.79 +/- 0.06
23:34:00 60 0.1156 18.07 +/- 0.06
23:45:06 120 0.3089 19.18 +/- 0.08
23:57:27 120 0.5147 19.68 +/- 0.10
00:29:01 300 1.0658 20.52 +/- 0.13
00:45:26 2 x 300 1.39333 20.48 +/- 0.09
This preliminary photometry is based on nearby USNO-B1 stars (R2 mag),
the magnitude is not corrected for MW extinction.
GCN Circular 34482
Subject
Fermi GRB 230818A: Global MASTER-Net observations report
Date
2023-08-19T01:33:49Z (2 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
legacy email
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko,
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov
(Blagoveschensk Educational State University)
MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 230818A ( Fermi GBM team, GCN 34478) errorbox 2 sec after notice time and 36 sec after trigger time at 2023-08-18 23:28:11 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 48 deg. The sun altitude is -28.4 deg.
MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 230818A errorbox 5 sec after notice time and 38 sec after trigger time at 2023-08-18 23:28:14 UT, with upper limit up to 18.1 mag. The observations began at zenith distance = 79 deg. The sun altitude is -17.2 deg.
MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 230818A errorbox 7 sec after notice time and 40 sec after trigger time at 2023-08-18 23:28:15 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 54 deg. The sun altitude is -26.2 deg.
The galactic latitude b = 13 deg., longitude l = 73 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2256099
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
41 | 2023-08-18 23:28:11 | MASTER-Tavrida | (19h 04m 27.69s , +40d 41m 46.2s) | C | 10 | 17.3 |
44 | 2023-08-18 23:28:14 | MASTER-OAFA | (19h 02m 32.62s , +40d 55m 41.9s) | C | 10 | 15.8 |
89 | 2023-08-18 23:28:14 | MASTER-OAFA | (19h 02m 32.61s , +40d 55m 41.9s) | C | 100 | 17.1 | Coadd
189 | 2023-08-18 23:28:14 | MASTER-OAFA | (19h 02m 32.61s , +40d 55m 41.9s) | C | 300 | 17.6 | Coadd
189 | 2023-08-18 23:28:14 | MASTER-OAFA | (19h 02m 32.61s , +40d 55m 41.9s) | C | 300 | 17.6 | Coadd
46 | 2023-08-18 23:28:15 | MASTER-Kislovodsk | (19h 03m 26.12s , +40d 50m 05.7s) | P- | 10 | 14.2 |
46 | 2023-08-18 23:28:15 | MASTER-Kislovodsk | (19h 03m 25.92s , +41d 13m 18.9s) | P| | 10 | 16.4 |
56 | 2023-08-18 23:28:15 | MASTER-Kislovodsk | (19h 03m 25.92s , +41d 13m 18.9s) | P| | 30 | 17.1 | Coadd
166 | 2023-08-18 23:28:15 | MASTER-Kislovodsk | (19h 03m 25.91s , +41d 13m 18.9s) | P| | 250 | 18.5 | Coadd
58 | 2023-08-18 23:28:28 | MASTER-Tavrida | (19h 04m 22.05s , +40d 40m 49.5s) | C | 10 | 17.9 |
64 | 2023-08-18 23:28:33 | MASTER-Kislovodsk | (19h 03m 23.93s , +40d 51m 33.7s) | P- | 10 | 14.2 |
64 | 2023-08-18 23:28:33 | MASTER-Kislovodsk | (19h 03m 23.75s , +41d 14m 47.2s) | P| | 10 | 16.5 |
75 | 2023-08-18 23:28:45 | MASTER-Tavrida | (19h 04m 22.15s , +40d 41m 48.6s) | C | 10 | 18.0 |
81 | 2023-08-18 23:28:51 | MASTER-Kislovodsk | (19h 03m 23.92s , +40d 50m 10.0s) | P- | 10 | 14.5 |
82 | 2023-08-18 23:28:51 | MASTER-Kislovodsk | (19h 03m 23.78s , +41d 13m 23.0s) | P| | 10 | 16.5 |
98 | 2023-08-18 23:29:02 | MASTER-Tavrida | (19h 04m 27.53s , +40d 40m 46.6s) | C | 20 | 18.3 |
94 | 2023-08-18 23:29:03 | MASTER-OAFA | (19h 02m 38.15s , +40d 54m 46.1s) | C | 10 | 15.6 |
104 | 2023-08-18 23:29:09 | MASTER-Kislovodsk | (19h 03m 26.06s , +40d 51m 22.5s) | P- | 20 | 16.0 |
104 | 2023-08-18 23:29:09 | MASTER-Kislovodsk | (19h 03m 25.95s , +41d 14m 36.8s) | P| | 20 | 17.2 |
129 | 2023-08-18 23:29:09 | MASTER-Kislovodsk | (19h 03m 25.95s , +41d 14m 36.8s) | P| | 70 | 17.8 | Coadd
125 | 2023-08-18 23:29:30 | MASTER-Tavrida | (19h 04m 22.51s , +40d 39m 45.1s) | C | 20 | 18.3 |
133 | 2023-08-18 23:29:38 | MASTER-Kislovodsk | (19h 03m 20.94s , +40d 50m 50.5s) | P- | 20 | 16.0 |
133 | 2023-08-18 23:29:38 | MASTER-Kislovodsk | (19h 03m 20.93s , +41d 14m 04.7s) | P| | 20 | 17.0 |
150 | 2023-08-18 23:29:50 | MASTER-OAFA | (19h 02m 33.15s , +40d 53m 48.4s) | C | 30 | 16.2 |
150 | 2023-08-18 23:29:50 | MASTER-OAFA | (19h 02m 33.15s , +40d 53m 48.4s) | C | 30 | 16.2 |
158 | 2023-08-18 23:29:57 | MASTER-Tavrida | (19h 04m 27.91s , +40d 39m 58.3s) | C | 30 | 18.4 |
166 | 2023-08-18 23:30:06 | MASTER-Kislovodsk | (19h 03m 20.88s , +40d 51m 47.9s) | P- | 30 | 16.1 |
166 | 2023-08-18 23:30:06 | MASTER-Kislovodsk | (19h 03m 20.92s , +41d 15m 01.9s) | P| | 30 | 17.5 |
200 | 2023-08-18 23:30:35 | MASTER-Tavrida | (19h 04m 25.14s , +40d 41m 36.2s) | C | 40 | 18.6 |
209 | 2023-08-18 23:30:44 | MASTER-Kislovodsk | (19h 03m 26.59s , +40d 50m 47.8s) | P- | 40 | 16.1 |
209 | 2023-08-18 23:30:44 | MASTER-Kislovodsk | (19h 03m 26.71s , +41d 14m 01.5s) | P| | 40 | 17.7 |
264 | 2023-08-18 23:30:44 | MASTER-Kislovodsk | (19h 03m 26.70s , +41d 14m 01.5s) | P| | 150 | 18.3 | Coadd
225 | 2023-08-18 23:31:00 | MASTER-OAFA | (19h 02m 39.38s , +40d 53m 58.2s) | C | 40 | 16.6 |
225 | 2023-08-18 23:31:00 | MASTER-OAFA | (19h 02m 39.38s , +40d 53m 58.2s) | C | 40 | 16.6 |
252 | 2023-08-18 23:31:22 | MASTER-Tavrida | (19h 04m 25.14s , +40d 39m 55.8s) | C | 50 | 18.6 |
262 | 2023-08-18 23:31:32 | MASTER-Kislovodsk | (19h 03m 20.78s , +40d 49m 45.3s) | P- | 50 | 16.2 |
262 | 2023-08-18 23:31:32 | MASTER-Kislovodsk | (19h 03m 21.04s , +41d 12m 58.3s) | P| | 50 | 17.8 |
289 | 2023-08-18 23:31:59 | MASTER-OAFA | (19h 02m 35.47s , +40d 55m 39.5s) | C | 50 | 16.8 |
289 | 2023-08-18 23:31:59 | MASTER-OAFA | (19h 02m 35.47s , +40d 55m 39.5s) | C | 50 | 16.8 |
315 | 2023-08-18 23:32:20 | MASTER-Tavrida | (19h 04m 28.52s , +40d 41m 33.0s) | C | 60 | 18.8 |
325 | 2023-08-18 23:32:30 | MASTER-Kislovodsk | (19h 03m 25.74s , +40d 50m 06.7s) | P- | 60 | 16.2 |
325 | 2023-08-18 23:32:30 | MASTER-Kislovodsk | (19h 03m 26.12s , +41d 13m 19.2s) | P| | 60 | 17.9 |
387 | 2023-08-18 23:33:27 | MASTER-Tavrida | (19h 04m 22.43s , +40d 40m 31.1s) | C | 70 | 18.9 |
389 | 2023-08-18 23:33:29 | MASTER-OAFA | (19h 02m 35.66s , +40d 54m 01.9s) | C | 70 | 16.8 |
389 | 2023-08-18 23:33:29 | MASTER-OAFA | (19h 02m 35.66s , +40d 54m 01.9s) | C | 70 | 16.8 |
398 | 2023-08-18 23:33:38 | MASTER-Kislovodsk | (19h 04m 24.74s , +41d 13m 15.6s) | P| | 70 | 12.3 |
475 | 2023-08-18 23:34:45 | MASTER-Tavrida | (19h 04m 21.84s , +40d 41m 27.3s) | C | 90 | 19.0 |
489 | 2023-08-18 23:34:59 | MASTER-OAFA | (19h 02m 39.29s , +40d 55m 39.9s) | C | 90 | 17.0 |
489 | 2023-08-18 23:34:59 | MASTER-OAFA | (19h 02m 39.29s , +40d 55m 39.9s) | C | 90 | 17.0 |
534 | 2023-08-18 23:34:59 | MASTER-OAFA | (19h 02m 39.29s , +40d 55m 39.8s) | C | 180 | 17.3 | Coadd
585 | 2023-08-18 23:36:24 | MASTER-Tavrida | (19h 04m 27.65s , +40d 40m 22.8s) | C | 110 | 19.0 |
628 | 2023-08-18 23:37:08 | MASTER-OAFA | (19h 02m 31.74s , +40d 54m 56.2s) | C | 110 | 17.2 |
628 | 2023-08-18 23:37:08 | MASTER-OAFA | (19h 02m 31.74s , +40d 54m 56.2s) | C | 110 | 17.2 |
712 | 2023-08-18 23:38:22 | MASTER-Tavrida | (19h 04m 22.34s , +40d 39m 18.4s) | C | 130 | 19.0 |
773 | 2023-08-18 23:39:18 | MASTER-OAFA | (19h 02m 32.53s , +40d 55m 57.9s) | C | 140 | 17.1 |
867 | 2023-08-18 23:40:42 | MASTER-Tavrida | (19h 04m 28.58s , +40d 39m 31.5s) | C | 160 | 19.1 |
967 | 2023-08-18 23:42:17 | MASTER-OAFA | (19h 02m 38.09s , +40d 54m 58.5s) | C | 170 | 17.3 |
1045 | 2023-08-18 23:43:30 | MASTER-Tavrida | (19h 04m 25.91s , +40d 41m 04.7s) | C | 180 | 19.1 |
1162 | 2023-08-18 23:45:27 | MASTER-OAFA | (19h 02m 31.91s , +40d 54m 00.8s) | C | 180 | 16.8 |
1233 | 2023-08-18 23:46:38 | MASTER-Tavrida | (19h 04m 26.01s , +40d 39m 01.5s) | C | 180 | 19.1 |
1258 | 2023-08-18 23:47:03 | MASTER-Kislovodsk | (19h 03m 21.94s , +40d 53m 32.1s) | C | 180 | 16.6 |
1258 | 2023-08-18 23:47:03 | MASTER-Kislovodsk | (19h 03m 26.43s , +41d 17m 09.3s) | C | 180 | 18.1 |
1423 | 2023-08-18 23:49:48 | MASTER-Tavrida | (19h 04m 29.85s , +40d 40m 44.6s) | C | 180 | 19.0 |
1459 | 2023-08-18 23:50:23 | MASTER-Kislovodsk | (19h 03m 21.84s , +40d 51m 33.0s) | C | 180 | 18.1 |
1639 | 2023-08-18 23:50:23 | MASTER-Kislovodsk | (19h 03m 21.84s , +40d 51m 33.0s) | C | 540 | 18.8 | Coadd
1459 | 2023-08-18 23:50:23 | MASTER-Kislovodsk | (19h 03m 26.64s , +41d 15m 12.7s) | C | 180 | 18.5 |
1612 | 2023-08-18 23:52:57 | MASTER-Tavrida | (19h 04m 22.42s , +40d 39m 49.1s) | C | 180 | 19.1 |
1659 | 2023-08-18 23:53:44 | MASTER-Kislovodsk | (19h 03m 24.49s , +40d 53m 10.0s) | C | 180 | 18.2 |
1659 | 2023-08-18 23:53:44 | MASTER-Kislovodsk | (19h 03m 29.72s , +41d 16m 49.4s) | C | 180 | 18.5 |
1839 | 2023-08-18 23:53:44 | MASTER-Kislovodsk | (19h 03m 29.72s , +41d 16m 49.2s) | C | 540 | 19.2 | Coadd
1802 | 2023-08-18 23:56:06 | MASTER-Tavrida | (19h 04m 24.04s , +40d 40m 43.5s) | C | 180 | 19.0 |
1991 | 2023-08-18 23:59:16 | MASTER-Tavrida | (19h 04m 30.28s , +40d 39m 37.6s) | C | 180 | 19.0 |
2066 | 2023-08-19 00:00:31 | MASTER-Kislovodsk | (19h 03m 19.42s , +40d 53m 01.7s) | C | 180 | 18.3 |
2066 | 2023-08-19 00:00:31 | MASTER-Kislovodsk | (19h 03m 25.40s , +41d 16m 38.0s) | C | 180 | 18.6 |
2181 | 2023-08-19 00:02:26 | MASTER-Tavrida | (19h 04m 23.56s , +40d 38m 32.6s) | C | 180 | 19.0 |
2267 | 2023-08-19 00:03:52 | MASTER-Kislovodsk | (19h 03m 24.05s , +40d 51m 55.1s) | C | 180 | 18.3 |
2447 | 2023-08-19 00:03:52 | MASTER-Kislovodsk | (19h 03m 24.02s , +40d 51m 55.0s) | C | 540 | 18.3 | Coadd
2267 | 2023-08-19 00:03:52 | MASTER-Kislovodsk | (19h 03m 30.34s , +41d 15m 31.0s) | C | 180 | 18.7 |
2371 | 2023-08-19 00:05:36 | MASTER-Tavrida | (19h 04m 29.48s , +40d 38m 45.7s) | C | 180 | 19.0 |
2553 | 2023-08-19 00:08:38 | MASTER-Kislovodsk | (19h 03m 26.78s , +40d 51m 59.9s) | P- | 180 | 17.1 |
2553 | 2023-08-19 00:08:38 | MASTER-Kislovodsk | (19h 03m 33.03s , +41d 15m 28.9s) | P| | 180 | 18.1 |
2733 | 2023-08-19 00:08:38 | MASTER-Kislovodsk | (19h 03m 33.03s , +41d 15m 28.9s) | P| | 540 | 18.7 | Coadd
2560 | 2023-08-19 00:08:45 | MASTER-Tavrida | (19h 04m 27.19s , +40d 40m 02.0s) | C | 180 | 18.9 |
2642 | 2023-08-19 00:10:07 | MASTER-OAFA | (19h 02m 31.47s , +40d 55m 53.4s) | C | 180 | 17.6 |
2748 | 2023-08-19 00:11:53 | MASTER-Tavrida | (19h 04m 27.32s , +40d 38m 25.3s) | C | 180 | 18.9 |
2753 | 2023-08-19 00:11:58 | MASTER-Kislovodsk | (19h 03m 23.68s , +40d 53m 29.5s) | P- | 180 | 17.2 |
2753 | 2023-08-19 00:11:58 | MASTER-Kislovodsk | (19h 03m 30.38s , +41d 16m 58.6s) | P| | 180 | 18.2 |
2877 | 2023-08-19 00:14:02 | MASTER-OAFA | (19h 02m 37.86s , +40d 54m 57.1s) | C | 180 | 17.8 |
2936 | 2023-08-19 00:15:01 | MASTER-Tavrida | (19h 04m 30.09s , +40d 39m 46.5s) | C | 180 | 18.8 |
2954 | 2023-08-19 00:15:19 | MASTER-Kislovodsk | (19h 03m 23.50s , +40d 51m 43.7s) | P- | 180 | 17.0 |
3134 | 2023-08-19 00:15:19 | MASTER-Kislovodsk | (19h 03m 23.50s , +40d 51m 43.6s) | P- | 540 | 17.6 | Coadd
2954 | 2023-08-19 00:15:19 | MASTER-Kislovodsk | (19h 03m 30.67s , +41d 15m 13.6s) | P| | 180 | 18.2 |
3114 | 2023-08-19 00:17:59 | MASTER-OAFA | (19h 02m 31.97s , +40d 53m 59.3s) | C | 180 | 17.9 |
3123 | 2023-08-19 00:18:08 | MASTER-Tavrida | (19h 04m 24.56s , +40d 39m 05.8s) | C | 180 | 18.8 |
3155 | 2023-08-19 00:18:39 | MASTER-Kislovodsk | (19h 03m 26.10s , +40d 53m 01.5s) | P- | 180 | 17.1 |
3155 | 2023-08-19 00:18:39 | MASTER-Kislovodsk | (19h 03m 33.83s , +41d 16m 32.2s) | P| | 180 | 18.1 |
3335 | 2023-08-19 00:18:39 | MASTER-Kislovodsk | (19h 03m 33.83s , +41d 16m 32.3s) | P| | 540 | 18.6 | Coadd
3311 | 2023-08-19 00:21:15 | MASTER-Tavrida | (19h 04m 24.82s , +40d 40m 00.4s) | C | 180 | 18.7 |
3355 | 2023-08-19 00:22:00 | MASTER-Kislovodsk | (19h 03m 19.81s , +40d 52m 23.1s) | P- | 180 | 17.0 |
3355 | 2023-08-19 00:22:00 | MASTER-Kislovodsk | (19h 03m 28.06s , +41d 15m 54.1s) | P| | 180 | 18.1 |
3498 | 2023-08-19 00:24:23 | MASTER-Tavrida | (19h 04m 31.83s , +40d 38m 54.8s) | C | 180 | 18.6 |
3516 | 2023-08-19 00:24:41 | MASTER-OAFA | (19h 02m 34.21s , +40d 55m 52.1s) | C | 180 | 17.8 |
3516 | 2023-08-19 00:24:41 | MASTER-OAFA | (19h 02m 34.21s , +40d 55m 52.1s) | C | 180 | 17.8 |
3555 | 2023-08-19 00:25:20 | MASTER-Kislovodsk | (19h 03m 18.96s , +40d 53m 14.5s) | P- | 180 | 17.0 |
3735 | 2023-08-19 00:25:20 | MASTER-Kislovodsk | (19h 03m 18.96s , +40d 53m 14.5s) | P- | 540 | 17.5 | Coadd
3555 | 2023-08-19 00:25:20 | MASTER-Kislovodsk | (19h 03m 27.59s , +41d 16m 45.5s) | P| | 180 | 18.0 |
3686 | 2023-08-19 00:27:31 | MASTER-Tavrida | (19h 04m 26.57s , +40d 37m 50.4s) | C | 180 | 18.6 |
3715 | 2023-08-19 00:28:00 | MASTER-OAFA | (19h 02m 34.00s , +40d 54m 26.3s) | C | 180 | 17.9 |
3715 | 2023-08-19 00:28:00 | MASTER-OAFA | (19h 02m 34.00s , +40d 54m 26.3s) | C | 180 | 17.9 |
3756 | 2023-08-19 00:28:41 | MASTER-Kislovodsk | (19h 03m 25.70s , +40d 52m 09.0s) | P- | 180 | 17.0 |
3756 | 2023-08-19 00:28:41 | MASTER-Kislovodsk | (19h 03m 34.73s , +41d 15m 39.4s) | P| | 180 | 18.0 |
3936 | 2023-08-19 00:28:41 | MASTER-Kislovodsk | (19h 03m 34.73s , +41d 15m 39.4s) | P| | 540 | 18.5 | Coadd
3877 | 2023-08-19 00:30:42 | MASTER-Tavrida | (19h 04m 31.80s , +40d 37m 54.0s) | C | 180 | 18.6 |
3956 | 2023-08-19 00:32:01 | MASTER-Kislovodsk | (19h 03m 19.48s , +40d 51m 00.6s) | P- | 180 | 17.0 |
3956 | 2023-08-19 00:32:01 | MASTER-Kislovodsk | (19h 03m 28.95s , +41d 14m 31.0s) | P| | 180 | 18.0 |
3989 | 2023-08-19 00:32:33 | MASTER-OAFA | (19h 02m 36.07s , +40d 55m 58.0s) | C | 180 | 17.5 |
3989 | 2023-08-19 00:32:33 | MASTER-OAFA | (19h 02m 36.07s , +40d 55m 58.0s) | C | 180 | 17.5 |
4034 | 2023-08-19 00:33:19 | MASTER-OAFA | (19h 02m 37.30s , +40d 55m 01.6s) | C | 180 | 17.0 |
4034 | 2023-08-19 00:33:19 | MASTER-OAFA | (19h 02m 37.30s , +40d 55m 01.6s) | C | 180 | 17.0 |
4066 | 2023-08-19 00:33:51 | MASTER-Tavrida | (19h 04m 28.83s , +40d 39m 32.6s) | C | 180 | 18.6 |
4157 | 2023-08-19 00:35:22 | MASTER-Kislovodsk | (19h 03m 25.50s , +40d 51m 05.7s) | P- | 180 | 17.0 |
4337 | 2023-08-19 00:35:22 | MASTER-Kislovodsk | (19h 03m 25.50s , +40d 51m 05.7s) | P- | 540 | 17.6 | Coadd
4157 | 2023-08-19 00:35:22 | MASTER-Kislovodsk | (19h 03m 35.40s , +41d 14m 36.0s) | P| | 180 | 18.0 |
4254 | 2023-08-19 00:36:59 | MASTER-Tavrida | (19h 04m 28.96s , +40d 37m 36.7s) | C | 180 | 18.6 |
4357 | 2023-08-19 00:38:42 | MASTER-Kislovodsk | (19h 03m 22.52s , +40d 52m 38.1s) | P- | 180 | 17.0 |
4357 | 2023-08-19 00:38:42 | MASTER-Kislovodsk | (19h 03m 32.76s , +41d 16m 08.7s) | P| | 180 | 18.0 |
4537 | 2023-08-19 00:38:42 | MASTER-Kislovodsk | (19h 03m 32.76s , +41d 16m 08.7s) | P| | 540 | 18.6 | Coadd
4441 | 2023-08-19 00:40:06 | MASTER-Tavrida | (19h 04m 32.13s , +40d 39m 19.8s) | C | 180 | 18.5 |
4558 | 2023-08-19 00:42:03 | MASTER-Kislovodsk | (19h 03m 22.46s , +40d 51m 03.8s) | P- | 180 | 17.1 |
4558 | 2023-08-19 00:42:03 | MASTER-Kislovodsk | (19h 03m 33.07s , +41d 14m 34.4s) | P| | 180 | 18.0 |
4629 | 2023-08-19 00:43:14 | MASTER-Tavrida | (19h 04m 27.31s , +40d 38m 24.6s) | C | 180 | 18.5 |
4662 | 2023-08-19 00:43:47 | MASTER-OAFA | (19h 02m 35.32s , +40d 55m 01.3s) | C | 180 | 17.7 |
4662 | 2023-08-19 00:43:47 | MASTER-OAFA | (19h 02m 35.32s , +40d 55m 01.3s) | C | 180 | 17.7 |
4758 | 2023-08-19 00:45:23 | MASTER-Kislovodsk | (19h 03m 25.24s , +40d 52m 27.5s) | P- | 180 | 17.0 |
4938 | 2023-08-19 00:45:23 | MASTER-Kislovodsk | (19h 03m 25.24s , +40d 52m 27.5s) | P- | 540 | 17.5 | Coadd
4758 | 2023-08-19 00:45:23 | MASTER-Kislovodsk | (19h 03m 36.19s , +41d 15m 58.0s) | P| | 180 | 18.0 |
4820 | 2023-08-19 00:46:25 | MASTER-Tavrida | (19h 04m 26.18s , +40d 39m 19.5s) | C | 180 | 18.6 |
4947 | 2023-08-19 00:48:32 | MASTER-OAFA | (19h 02m 35.77s , +40d 54m 19.3s) | C | 180 | 16.8 |
4947 | 2023-08-19 00:48:32 | MASTER-OAFA | (19h 02m 35.77s , +40d 54m 19.3s) | C | 180 | 16.8 |
4959 | 2023-08-19 00:48:44 | MASTER-Kislovodsk | (19h 03m 18.30s , +40d 51m 25.8s) | P- | 180 | 17.0 |
4959 | 2023-08-19 00:48:44 | MASTER-Kislovodsk | (19h 03m 29.69s , +41d 14m 55.6s) | P| | 180 | 18.0 |
5139 | 2023-08-19 00:48:44 | MASTER-Kislovodsk | (19h 03m 29.69s , +41d 14m 55.6s) | P| | 540 | 18.4 | Coadd
5007 | 2023-08-19 00:49:32 | MASTER-Tavrida | (19h 04m 32.82s , +40d 38m 14.5s) | C | 180 | 18.5 |
5195 | 2023-08-19 00:52:39 | MASTER-Tavrida | (19h 04m 27.62s , +40d 37m 10.2s) | C | 180 | 18.5 |
5360 | 2023-08-19 00:55:25 | MASTER-Kislovodsk | (19h 03m 24.81s , +40d 51m 11.9s) | P- | 180 | 16.9 |
5360 | 2023-08-19 00:55:25 | MASTER-Kislovodsk | (19h 03m 36.96s , +41d 14m 41.4s) | P| | 180 | 17.8 |
5385 | 2023-08-19 00:55:50 | MASTER-Tavrida | (19h 04m 33.92s , +40d 37m 26.2s) | C | 180 | 18.6 |
5560 | 2023-08-19 00:58:45 | MASTER-Kislovodsk | (19h 03m 17.85s , +40d 50m 03.1s) | P- | 180 | 17.0 |
5740 | 2023-08-19 00:58:45 | MASTER-Kislovodsk | (19h 03m 17.85s , +40d 50m 03.1s) | P- | 540 | 17.3 | Coadd
5560 | 2023-08-19 00:58:45 | MASTER-Kislovodsk | (19h 03m 30.45s , +41d 13m 33.0s) | P| | 180 | 17.8 |
5573 | 2023-08-19 00:58:58 | MASTER-Tavrida | (19h 04m 30.63s , +40d 38m 50.1s) | C | 180 | 18.5 |
5761 | 2023-08-19 01:02:05 | MASTER-Kislovodsk | (19h 03m 24.65s , +40d 50m 08.8s) | P- | 180 | 16.8 |
5761 | 2023-08-19 01:02:06 | MASTER-Kislovodsk | (19h 03m 37.62s , +41d 13m 38.4s) | P| | 180 | 17.6 |
5941 | 2023-08-19 01:02:06 | MASTER-Kislovodsk | (19h 03m 37.62s , +41d 13m 38.4s) | P| | 540 | 18.1 | Coadd
5761 | 2023-08-19 01:02:06 | MASTER-Tavrida | (19h 04m 30.82s , +40d 37m 18.8s) | C | 180 | 18.5 |
5840 | 2023-08-19 01:03:25 | MASTER-OAFA | (19h 02m 28.43s , +40d 55m 54.7s) | C | 180 | 17.9 |
5840 | 2023-08-19 01:03:25 | MASTER-OAFA | (19h 02m 28.43s , +40d 55m 54.7s) | C | 180 | 17.9 |
5949 | 2023-08-19 01:05:14 | MASTER-Tavrida | (19h 04m 34.73s , +40d 38m 37.4s) | C | 180 | 18.4 |
5961 | 2023-08-19 01:05:26 | MASTER-Kislovodsk | (19h 03m 21.57s , +40d 51m 24.2s) | P- | 180 | 16.7 |
5961 | 2023-08-19 01:05:26 | MASTER-Kislovodsk | (19h 03m 34.90s , +41d 14m 54.1s) | P| | 180 | 17.5 |
6082 | 2023-08-19 01:07:26 | MASTER-OAFA | (19h 02m 34.34s , +40d 54m 53.2s) | C | 180 | 18.0 |
6082 | 2023-08-19 01:07:26 | MASTER-OAFA | (19h 02m 34.34s , +40d 54m 53.2s) | C | 180 | 18.0 |
6139 | 2023-08-19 01:08:24 | MASTER-Tavrida | (19h 04m 28.83s , +40d 37m 45.8s) | C | 180 | 18.4 |
6162 | 2023-08-19 01:08:47 | MASTER-Kislovodsk | (19h 03m 35.31s , +41d 13m 27.2s) | P| | 180 | 17.3 |
6162 | 2023-08-19 01:08:47 | MASTER-Kislovodsk | (19h 03m 21.57s , +40d 49m 57.6s) | P- | 180 | 16.6 |
6301 | 2023-08-19 01:11:06 | MASTER-OAFA | (19h 02m 28.75s , +40d 53m 52.5s) | C | 180 | 18.0 |
6326 | 2023-08-19 01:11:31 | MASTER-Tavrida | (19h 04m 29.40s , +40d 38m 41.0s) | C | 180 | 18.4 |
6362 | 2023-08-19 01:12:07 | MASTER-Kislovodsk | (19h 03m 23.15s , +40d 51m 24.1s) | P- | 180 | 16.2 |
6362 | 2023-08-19 01:12:07 | MASTER-Kislovodsk | (19h 03m 37.34s , +41d 14m 54.1s) | P| | 180 | 16.9 |
6516 | 2023-08-19 01:14:41 | MASTER-Tavrida | (19h 04m 35.04s , +40d 37m 36.4s) | C | 180 | 18.2 |
6521 | 2023-08-19 01:14:46 | MASTER-OAFA | (19h 02m 33.90s , +40d 54m 16.7s) | C | 180 | 18.1 |
6563 | 2023-08-19 01:15:27 | MASTER-Kislovodsk | (19h 03m 17.09s , +40d 50m 26.2s) | P- | 180 | 16.0 |
6563 | 2023-08-19 01:15:28 | MASTER-Kislovodsk | (19h 03m 31.77s , +41d 13m 56.3s) | P| | 180 | 16.5 |
6707 | 2023-08-19 01:17:52 | MASTER-Tavrida | (19h 04m 29.10s , +40d 36m 31.7s) | C | 180 | 18.2 |
6897 | 2023-08-19 01:21:02 | MASTER-Tavrida | (19h 04m 35.81s , +40d 36m 39.4s) | C | 180 | 18.1 |
7088 | 2023-08-19 01:24:13 | MASTER-Tavrida | (19h 04m 32.58s , +40d 38m 07.9s) | C | 180 | 18.1 |
7276 | 2023-08-19 01:27:20 | MASTER-Tavrida | (19h 04m 32.71s , +40d 36m 37.4s) | C | 180 | 17.9 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 34480
Subject
GRB 230818A: GOTO optical afterglow detection
Date
2023-08-19T01:17:17Z (2 years ago)
From
Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>
Via
email
B. P. Gompertz, A. Kumar, K. Wiersema, B. Godson, D. O’Neill, B. Warwick, R. Starling, K. Ackley; M. J. Dyer; J. Lyman; K. Ulaczyk; F. Jimenez-Ibarra; D. Steeghs; D. K. Galloway; V. Dhillon; P. O'Brien; G. Ramsay; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:
The Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) observed the field of the X-ray (Tohuvavohu et al., GCN 34479) and optical (Lipunov et al, GCN 34476) counterparts to GRB 230818A (Fermi GBM Team, GCN 34478; Tohuvavohu et al., GCN 34479) at 23:32:00 UT on 2023-08-18, 266 seconds after trigger. The observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm).
Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using recent survey observations of the same pointing. We detect the optical counterpart reported by MASTER (GCN 34476) with a preliminary magnitude of L = 17.75 ± 0.02 mag.
Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.
Observations are ongoing.
GOTO (https://goto-observatory.org) is a network of telescopes operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).
GCN Circular 34479
Subject
GRB 230818A: Swift detection of a burst
Date
2023-08-18T23:44:09Z (2 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
Via
email
A. Tohuvavohu (U Toronto), S. Dichiara (PSU), J.D. Gropp (PSU),
D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII),
B. Sbarufatti (INAF-OAB) and M. A. Williams (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 23:27:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230818A (trigger=1186032). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 285.883, +40.876 which is
RA(J2000) = 19h 03m 32s
Dec(J2000) = +40d 52' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single complex
peak structure with a duration of about 10 sec. The peak count rate
was ~6000 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 23:29:55.4 UT, 141.1 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 285.88966, 40.89504 which is equivalent
to:
RA(J2000) = 19h 03m 33.52s
Dec(J2000) = +40d 53' 42.1"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 70 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. We
cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.13
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 144 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.101.
Burst Advocate for this burst is A. Tohuvavohu (aaron.tohu AT gmail.com).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)
GCN Circular 34478
Subject
GRB 230818A: Fermi GBM Final Real-time Localization
Date
2023-08-18T23:38:02Z (2 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 23:27:35 UT on 18 Aug 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230818A (trigger 714094060.372856 / 230818977).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 289.2, Dec = 41.0 (J2000 degrees, equivalent to J2000 19h 16m, 41d 00'), with a statistical uncertainty of 2.7 degrees.
The angle from the Fermi LAT boresight is 79.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230818977/quicklook/glg_skymap_all_bn230818977.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230818977/quicklook/glg_healpix_all_bn230818977.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230818977/quicklook/glg_lc_medres34_bn230818977.gif