GRB 240809A
GCN Circular 37110
Subject
GRB 240809A: Swift detection of a burst with a bright optical counterpart
Date
2024-08-09T08:44:45Z (a year ago)
From
P.A. Evans at U. Leicester <pae9@leicester.ac.uk>
Via
email
P. A. Evans (U Leicester), R. A. J. Eyles-Ferris (U Leicester),
K. L. Page (U Leicester) and A. Tohuvavohu (U Toronto) report on
behalf of the Neil Gehrels Swift Observatory Team:
At 08:30:29 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 240809A (trigger=1247745). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 237.551, -2.321 which is
RA(J2000) = 15h 50m 12s
Dec(J2000) = -02d 19' 15"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 30 sec. The peak count rate
was ~22500 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 08:31:57.9 UT, 88.3 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 237.5464, -2.3178 which is equivalent to:
RA(J2000) = 15h 50m 11.14s
Dec(J2000) = -02d 19' 04.1"
with an uncertainty of 12 arcseconds (radius, 90% containment). This
location is 20 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 98 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 15:50:10.51 = 237.54381
DEC(J2000) = -02:19:03.2 = -2.31756
with a 90%-confidence error radius of about 0.61 arc sec. This position is 9.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.47 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.249.
Burst Advocate for this burst is P. A. Evans (pae9 AT leicester.ac.uk).
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 37113
Subject
GRB 240809A: SVOM/GRM observation
Date
2024-08-09T12:04:42Z (a year ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Yue Huang, Yong-Wei Dong, Jiang-Tao Liu, Shi-Jie Zheng, Jian-Chao Sun, Wen-Jun Tan, Jiang He, Min Gao, Hao-Xuan Guo, Lu Li, Yong-Ye Li, Hong-Wei Liu, Xin Liu, Hao-Li Shi, Li-Ming Song, You-Li Tuo, Hao-Xi Wang, Jin Wang, Jin-Zhou Wang, Ping Wang, Rui-Jie Wang, Yu-Xi Wang, Bo-Bing Wu, Shao-Lin Xiong, Jian-Ying Ye, Yi-Tao Yin, Wen-Hui Yu, Fan Zhang, Li Zhang, Peng Zhang, Shuang-Nan Zhang, Wen-Long Zhang, Yan-Ting Zhang, Shu-Min Zhao, Xiao-Yun Zhao, Chao Zheng (IHEP), Maria-Grazia Bernardini (LUPM/INAF-OAB), Laurent Bouchet (IRAP), David Corre (CEA), Tais Maiolino (LUPM), Frédéric Piron (LUPM) , Stéphane Schanne (CEA), Jingwei Wang (IAP)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), JeanLuc Attéia (IRAP), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Bing Zhang (UNLV)
report on behalf of the SVOM team:
During the commissioning phase, the SVOM/GRM was triggered in-flight by a long GRB 240809A at 2024-08-09T08:30:28 UT (T0), which also triggered Swift/BAT (GCN 37110).
The real-time alert data and light curves of SVOM/GRM were downlinked to the ground through the VHF system with low latency. The light curves show that this burst consists of a single pulse with a T90 of 13.0+1.1 s.
The GRM light curve can be found here:
https://www.bursthub.cn/admin/static/svgrb240809A.png
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)
GCN Circular 37114
Subject
GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
Date
2024-08-09T12:38:21Z (a year ago)
From
maedubay@unc.edu
Via
Web form
Megan Dubay, Dylan Dutton, Donovan Schlekat, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, Ruide Fu, Arie Verveer, Daryl Janzen, John Kennewall, Colin Armstrong, Ken Stranger (Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill); Michael Fitzgerald, Wayne Rosing, Andrew Yen (Photon Ranch/Las Cumbres Observatory).
We observed the field of GRB 240809A with one of the Photon Ranch’s 0.4m telescopes at Eltham College Observatory (ECO1) beginning at ~540s post-trigger by the Swift-BAT instrument. Continuing observations on both the ECO1 telescope and Skynet’s PROMPT telescopes at both Meckering Observatory and Perth Observatory are underway. Our first detection occurred at 09:42 UTC on August 9, 2024, approximately 40 minutes after the optical counterpart discovery by Swift (Evans et al., GCN 37110).
We detect the optical afterglow at coordinates consistent with the reported coordinates from the Swift-UVOT observation.
The coordinates are:
R.A. (J2000): 15:50:10.47
Dec. (J2000): -02:19:02.89
We report the most recent photometry below. Additional measurements are underway.
ExpLen | Telescope | Filter | Mag | Mag Error | MJD
——————————————————————————————————————————————————————————————————
155 | PROMPT-MO-1 | I | 17.798 | 0.101 | 60531.4581
186 | PROMPT-MO-1 | R | 18.125 | 0.069 | 60531.4561
254 | R-COP | R | 18.634 | 0.253 | 60531.4669
Our images have been calibrated using stars from the APASS catalog.
GCN Circular 37115
Subject
GRB 240809A: Enhanced Swift-XRT position
Date
2024-08-09T14:00:39Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1278 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 240809A, 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 = 237.54399, -2.31789 which is equivalent
to:
RA (J2000): 15h 50m 10.56s
Dec (J2000): -02d 19' 04.4"
with an uncertainty of 2.0 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 37116
Subject
GRB 240809A: JinShan optical observations
Date
2024-08-09T17:17:02Z (a year ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Via
Web form
S.Q. Jiang, Z.P. Zhu, S.Y. Fu, X. Liu, J. An, D. Xu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration:
We observed the field of GRB 240809A detected by Swift (Evans et al. GCN 37110) using the 100C telescope of the JinShan project located at Altay, Xinjiang, China. A series of 200 s and 300 s frames were obtained in the Sloan g-, r-, i- and z- bands, starting at 15:08:20.24 UT on 2024-08-09, i.e., 6.63 hr after the Swift/BAT trigger.
The optical afterglow (Evans et al. GCN 37110; Dubay et al. GCN 37114) of the burst is clearly detected in our stacked images. Preliminary photometric results are as follows:
-----------------------------------------------------------------
Tmid-T0(hr) Exp(s) Filter Mag+/-MagErr
-----------------------------------------------------------------
7.404 3x200 g 20.05 +/- 0.05
7.578 3x200 r 19.86 +/- 0.09
6.758 3x300 i 19.49 +/- 0.04
7.100 5x300 z 19.47 +/- 0.08
-----------------------------------------------------------------
calibrated with nearby PanSTARRS stars and not corrected for Galactic extinction.
We acknowledge the excellent support from S.W Luo, M.M. Yang, Z. K. Feng, Q. C. Zhao and L.F. Huo for enabling these observations.
GCN Circular 37117
Subject
Swift GRB 240809A: Global MASTER-Net observations report
Date
2024-08-09T17:46:34Z (a year 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, V.Senik, D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(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),
V. Yurkov, A. Gabovich
(Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global 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 Swift GRB 240809A ( P. A. Evans et al., GCN 37110) errorbox 32075 sec after notice time and 32089 sec after trigger time at 2024-08-09 17:25:19 UT, with upper limit up to 16.4 mag. Observations started at twilight. The observations began at zenith distance = 30 deg. The sun altitude is -16.8 deg.
The galactic latitude b = 37 deg., longitude l = 6 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2556110
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
32180 | MASTER-SAAO | C | 180 | 16.4 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 37121
Subject
GRB 240809A: Swift-XRT refined Analysis
Date
2024-08-09T22:48:09Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato
(INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), J. D. Gropp
(PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester) and P.A. Evans
report on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 240809A, from 77 s to 45.8
ks after the BAT trigger. The data comprise 1.3 ks 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 a series of power-law decays. The
initial decay index is alpha=1.02 (+0.06, -0.05). At T+257 s the decay
flattens to an alpha of 0.825 (+/-0.028) before breaking again at
T+2884 s to a final decay with index alpha=1.57 (+/-0.06).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.706 (+/-0.030). The
best-fitting absorption column is 1.94 (+0.13, -0.12) x 10^21 cm^-2,
in excess of the Galactic value of 1.5 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.66 (+/-0.10) and a
best-fitting absorption column of 1.9 (+/-0.4) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 4.4 x 10^-11 (5.3 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.9 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^21 cm^-2
Excess significance: 1.8 sigma
Photon index: 1.66 (+/-0.10)
If the light curve continues to decay with a power-law decay index of
1.57, the count rate at T+24 hours will be 0.050 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.2 x
10^-12 (2.6 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01247745.
This circular is an official product of the Swift-XRT team.
GCN Circular 37122
Subject
GRB 240809A: Tentative redshift from NOT
Date
2024-08-09T23:39:17Z (a year ago)
From
Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>
Via
email
Rashmi Gottumukkala (DAWN/NBI), Chandana Chandrasherkhar Hegde (DAWN/DTU), Jens Reersted Larsen (IFA), Ulrika Woulhoj Jakobsen (DTU), Rasmus Damgaard Nielsen (DAWN/NBI), Nikolaj Bjerregaard Sillassen (DAWN/DTU), Albert Bjerregard Sneppen (DAWN/NBI), Johan P. U. Fynbo (DAWN/NBI), Antonio de Ugarte Postigo (CNRS), Daniele B. Malesani (DAWN/NBI and Radboud Univ.) and Nial R. Tanvir (U. Leicester) report:
We observed the afterglow of GRB 240809A (Evans et al. GCN 37110; Want et al. GCN37113; Dubai et al. GCN37114; Jiang et al. GCN 37116) with ALFOSC on the 2.5 m Nordic Optical Telescope (La Palma, Spain). The observation consisted of 300 s imaging in r-band followed by 4x1200 s spectroscopy covering the range between 3500 and 9500 AA. The observation started at 2024 Aug 9.87846 UT, 12.575 hr after the burst.
The afterglow is well detected in imaging at r ~ 20.3 mag. The spectrum shows continuum emission over the complete spectral range. We identify marginal spectral features which seem to match Mg II, Mg I and Fe II at a common redshift of 1.495, which we propose as the most likely redshift of this GRB.
Further observations to confirm this measurement are encouraged.
GCN Circular 37123
Subject
GRB 240809A: Swift/UVOT Detection
Date
2024-08-10T01:58:51Z (a year ago)
From
Sam Shilling at Lancaster University <shilling.sam@gmail.com>
Via
Web form
S.P.R. Shilling (Lancaster U.) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 240809A
98 s after the BAT trigger (Evans et al., GCN Circ. 37110).
A source consistent with the enhanced XRT position
(Osborne et al., GCN Circ. 37115) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 15:50:10.52 = 237.54385 (deg.)
Dec (J2000) = -02:19:03.0 = -2.31751 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).
Preliminary detections using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 98 248 147 14.42 +/- 0.02
v 640 660 19 16.11 +/- 0.14
b 565 585 19 16.28 +/- 0.09
u 310 560 246 15.13 +/- 0.03
w1 689 709 19 16.19 +/- 0.17
m2 665 1263 78 17.31 +/- 0.18
w2 616 1387 97 18.33 +/- 0.24
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.249 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 37125
Subject
GRB 240809A: GIT afterglow observations
Date
2024-08-10T04:21:01Z (a year ago)
From
Varun Bhalerao at IIT Bombay <varunb@iitb.ac.in>
Via
Web form
T. Mohan, A. Mehla, R. Kumar, V. Swain, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the field of GRB 240809A detected by Swift (Evans et al., GCN 37110; optical follow-up Dubay et al GCN 37114; Jiang et al GCN 37116; Lipunov et al GCN 37117; Gottumukkala et al GCN 37122) with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2024-08-09 17:15:14 UT, i.e., 8.75 hours after the Swift trigger. We obtained one exposure of 300 seconds in the r' filter. In our image, we clearly detected the afterglow at the coordinates reported by Swift/UVOT Detection (Evans et al., GCN 37110). The photometry results follow as:
--------------------------------------------------------------------------------------------------
| JD (mid) | t-t0 (hours) | Filter | Total Exposure (s) | Magnitude (AB) | Limiting mag |
| ----------------- | ------------ |------- | ------------------ | -------------- | ------------ |
| 2460532.218912037 | 8.75 | r' | 300 | 19.8 +/- 0.2 | 20.26 |
--------------------------------------------------------------------------------------------------
Our observations are consistent with those reported by Dubay et al. in GCN 37114 and Jiang et al. in GCN 37116. The magnitude is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular 37127
Subject
GRB 240809A: KAIT optical observations
Date
2024-08-10T06:19:23Z (a year ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
legacy email
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to GRB 240809A detected by Swift
(Evans et al., GCN 37110) starting about 0.86 days after the bust.
Observations were performed in the clear (roughly R) filter, and
the exposure time was 60s per image. A total of 30 images were
obtained. We detected the optical afterglow (Evans et al.,
GCN 37110; Dubay et al., GCN 37114; Jiang et al., GCN 37116;
Gottumukkala et al., GCN 37122; Mohan et al., GCN 37125) in our
coadd image in clear band. We measured its brightness of 21.0 +/-
0.2 mag at a mid time of ~0.86 days after the burst, calibrated to
the Pan-STARRS1 catalog.
GCN Circular 37129
Subject
GRB 240809A: Conclusive redshift from VLT
Date
2024-08-10T10:16:16Z (a year ago)
From
Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl>
Via
Web form
B. Schneider (MIT), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. de Ugarte Postigo (CNRS), J. P. U. Fynbo (DAWN/NBI), R. Gottumukkala (DAWN/NBI), L. Izzo (INAF/OACn and DARK/NBI), N. R. Tanvir (Univ. Leicester), D. Xu (NAOC), report on behalf of the Stargate collaboration:
We observed the afterglow of GRB 240809A (Evans et al., GCN 37110; Wang et al., GCN 37113; Dubay et al., GCN 37114; Jiang et al., GCN 37116; Gottumukkala et al., GCN 37122; Shilling & Evans, GCN 37123; Mohan et al., GCN 37125; Zheng & Filippenko, GCN 37127) using the X-shooter spectrograph mounted on the ESO VLT UT3 (Melipal). The observation mid time was 2024 Aug 10.056 UT (16.84 hr after the GRB), consisted of 6 exposures of 600 s each and covered the wavelength range 3000-21000 AA.
In images taken with the acquisition camera, we clearly detect the optical afterglow. In the r band, we measure an AB magnitude of r ~ 20.9, calibrated against the Pan-STARRS catalog.
In a preliminary reduction, we clearly detect continuum over the entire wavelength range. From detection of multiple absorption features, which we interpret as due to Fe II, Mg II, C IV, Al lI and Si II, we infer a common redshift of z = 1.494. No emission lines from the underlying host galaxy are detected in a preliminary analysis. This redshift is perfectly consistent with the value by Gottumukkala et al. (GCN 37122). We thus confirm that z = 1.494 is the redshift of GRB 240809A. We also note the presence of additional absorption features, likely due to an intervening system at z = 0.844.
We acknowledge expert support from the ESO staff in Paranal, in particular Maria Jose Rain, Rob van Holstein, and Boris Haeussler.
GCN Circular 37131
Subject
GRB 240809A: Bassano Bresciano Observatory optical observations
Date
2024-08-10T12:21:02Z (a year ago)
From
Ulisse Quadri at Bassano Bresciano Observatory <osservatoriobassano@gmail.com>
Via
Web form
U.Quadri, L.Strabla and P.Madurini (Bassano Bresciano Astronomical Observatory),
Members of:
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/SSV-GRB section.
GAC - Gruppo Astrofili Cremonesi.
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 imaged the field of GRB 240809A detected by SWIFT(trigger 1247745) with the robotic telescope of (IAU station 565) Bassano Bresciano Observatory, Italy.
The observations started 11.38 hours after the GRB trigger, At the end of twilight with our Newton telescope D=450 mm F/D=4.5.
We co-added 150 exposures of 20 sec each (total 50 min).
Start T0+ End T0+ CR lim
11.38 hour 12.29 hour 20.6
We detected a (fading) afterglow in the error box of the XRTcandidate (Evans et al., GCN 37110; Wang et al., GCN 37113; Dubay et al., GCN 37114; Jiang et al., GCN 37116; V. Lipunov et al., GCN 37117; Gottumukkala et al., GCN 37122; Shilling & Evans, GCN 37123; Mohan et al., GCN 37125; Zheng & Filippenko, GCN 37127; B. Schneider et al., GCN 37129) at the following position (+/- 3 arcsec):
RA (J2000.0) = 15 50 10.46
DEC(J2000.0) = -02 19 04.6
The results of our photometry are:
---------------------------------------------
Date UT Exp Afterglow
Middle (Min) CR-mag
---------------------------------------------
2024 08 09.84773 50 19.7 +/- 0.2
---------------------------------------------
CR magnitude is unfiltered with R zero point.
Comparison stars used:
------------------------------
Pan-STARRS obj ID R-Mag
------------------------------
105212375756448208 16.639
105202375684658035 17.916
105202375288851708 17.912
105192375172794156 17.312
105182375066235940 17.998
------------------------------
Magnitudes were estimated with the pan-STARRS cat and are derived using Lupton (2005) equations and are not corrected for galactic dust extinction.
Reference:
http://www.osservatoriobassano.org/grb.asp
The message may be cited.
GCN Circular 37132
Subject
GRB 240809A: REM detection of the optical afterglow
Date
2024-08-10T19:17:29Z (a year ago)
Edited On
2024-08-12T18:22:56Z (a year ago)
From
Riccardo Brivio <riccardo.brivio@inaf.it>
Edited By
Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov> on behalf of Sam Shilling at Lancaster University <shilling.sam@gmail.com>
Via
Web form
R. Brivio, Y.-D. Hu, S. Covino, P. D’Avanzo, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 240809A (Evans et al., GCN 37110; Want et al., GCN 37113; Dubai et al., GCN 37114; Jiang et al., GCN 37116) with the REM 60cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, J, H, K bands, starting on 2024 August 09 at 23:07:36 UT (i.e. 14.6 hours after the burst), and lasting for about 1 hour.
From preliminary photometry, we detect the optical afterglow at a position consistent with the UVOT detection (Shilling & Evans, GCN 37123), at the following AB magnitude in the r band:
r = 20.75 +- 0.20 (calibrated against PanSTARRS catalogue)
at a mid-time of t-t0 ~ 15.1 hours after the GRB trigger.
GCN Circular 37134
Subject
GRB240809A: Liverpool Telescope optical follow-up observations
Date
2024-08-10T21:29:26Z (a year ago)
From
A. Bochenek at Liverpool John Moores University <a.m.bochenek@2023.ljmu.ac.uk>
Via
Web form
A. Bochenek and D. A. Perley (LJMU) report:
We observed the Gamma-Ray Burst GRB240809A (Evans et al. GCN 37110 ; Want et al. GCN37113) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 5x120s exposures with the SDSS-R and SDSS-I filters starting at 2024-08-09 21:48:46 UT, approximately 13.3 hours after the trigger.
The afterglow is detected in every exposure at a position consistent with previous detections reported by Dubay et al. (GCN 37114) and Jiang et al. (GCN 37116). The obtained results are given below:
MJD (mid) T_mid - T_0 Filter Mag. (AB)
60531.91279 13.40 h r 20.54 ± 0.05
60531.18419 13.60 h i 20.43 ± 0.05
The photometry was obtained using nearby PanSTARRS secondary standards and was not corrected for extinction.
GCN Circular 37139
Subject
Konus-Wind detection of GRB 240809A
Date
2024-08-11T17:39:32Z (a year ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long-duration GRB 240809A
(Swift-BAT detection: Evans et al., GCN 37110;
SVOM-GRM detection: Wang et al., GCN 37113)
triggered Konus-Wind at T0=30629.035 s UT (08:30:29.035).
The burst light curve shows a multipeaked structure
which starts at ~T0-4.7 s and has a total duration of ~36.9 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240809_T30629/
As observed by Konus-Wind, the burst
had a fluence of 1.30(-0.09,+0.09)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+5.488 s,
of 3.14(-0.45,+0.44)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+32.768 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.84(-0.07,+0.07),
the high energy photon index beta = -2.54(-0.62,+0.28),
the peak energy Ep = 1097(-146,+164) keV
(chi2 = 118/97 dof).
The spectrum near the maximum count rate
(measured from T0+0.256 to T0+6.144 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.59(-0.07,+0.08),
the high energy photon index beta = -2.50(-0.32,+0.21),
the peak energy Ep = 1240(-146,+160) keV
(chi2 = 111/82 dof).
Assuming the redshift z=1.494 (Schneider et al., GCN 37129)
and a standard cosmology model with H_0 = 67.3 km/s/Mpc,
Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is 7.8(-0.5,+0.5)x10^53 erg,
the peak luminosity L_iso is 4.7(-0.7,+0.7)x10^53 erg/s,
the rest-frame peak energy of the time-integrated spectrum Ep,i,z is 2736(-364,+409) keV,
and the rest-frame peak energy at the peak of the emission Ep,p,z is 3093(-364,+399) keV.
With the obtained estimates, GRB 240809A is inside 90% prediction bands
for both 'Amati' and 'Yonetoku' relations 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/GRB240809_T30629/GRB240809A_rest_frame.pdf
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 37154
Subject
GRB 240809A: Swift-BAT refined analysis
Date
2024-08-12T18:06:35Z (a year ago)
From
Tyler Parsotan at NASA GSFC <tyler.parsotan@nasa.gov>
Via
email
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC),
R. Gupta (GSFC), H. A. Krimm (NSF),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. J. Moss (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC),
T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 240809A (trigger #1247745)
(Evans, et al., GCN Circ. 37110). The BAT ground-calculated position is
RA, Dec = 237.545, -2.331 deg which is
RA(J2000) = 15h 50m 10.8s
Dec(J2000) = -02d 19' 51.1"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 72%.
The mask-weighted light curve shows a single peaked fast rise exponential decay
structure with a tail that lasts until ~100 seconds after the trigger time.
T90 (15-350 keV) is 72.86 +- 19.39 sec (estimated error including systematics).
The time-averaged spectrum from -10.876 to 180.52 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.17 +- 0.05. The fluence in the 15-150 keV band is 9.7 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+2.68 sec in the 15-150 keV band
is 12.8 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1247745
GCN Circular 37157
Subject
GRB 240809A: ALMA detection
Date
2024-08-12T21:44:40Z (a year ago)
From
Tanmoy Laskar at U of Bath <tanmoylaskar@gmail.com>
Via
legacy email
T. Laskar (University of Utah), C. Christy (University of Arizona), K. D.
Alexander (University of Arizona), G. Schroeder (Northwestern University),
C. Peña (University of Utah), E. Berger (Harvard University), R. Chornock
(UC Berkeley), W. Fong (Northwestern University), R. Margutti (UC
Berkeley), and P. Schady (University of Bath) report on behalf of a larger
collaboration:
"We observed GRB 240809A (Evans et al., GCN 37110) with the Atacama Large
Millimeter/Submillimeter Array (ALMA) at 97.5 GHz over two epochs,
beginning on 2024 August 09 19:30 UT and 2024 August 10 23:28 UT, at 11 h
and 39 h after the burst, respectively. Preliminary analysis reveals a
fading mm source, with flux density of ~ 0.1 mJy in the first epoch, which
we identify as the radio counterpart of GRB 240809A. Further observations
are planned.
We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help
with these observations."
GCN Circular 37158
Subject
GRB 240809A: VLA detection
Date
2024-08-12T21:45:54Z (a year ago)
From
Tanmoy Laskar at U of Bath <tanmoylaskar@gmail.com>
Via
legacy email
C. Christy (University of Arizona), T. Laskar (University of Utah), K. D.
Alexander (University of Arizona), G. Schroeder (Northwestern University),
C. Peña (University of Utah), E. Berger (Harvard University), R. Chornock
(UC Berkeley), W. Fong (Northwestern University), R. Margutti (UC
Berkeley), and P. Schady (University of Bath) report on behalf of a larger
collaboration:
"We observed GRB 240809A (Evans et al., GCN 37110) with the Karl G. Jansky
Very Large Array (VLA) beginning on 2024 August 10 02:25 UTC (17.9 h after
the burst) at multiple frequencies. In preliminary analysis, we detect the
radio counterpart (Laskar et al., GCN 37157) with a flux density of ~ 0.2
mJy at 15 GHz, and position:
RA (J2000) = 15h 50m 10.5s
Dec (J2000) = -02d 19' 5.1"
with a (statistical) uncertainty of 0.2" in each coordinate. This position
is consistent with the X-ray and optical position (Evans et al., GCN
37110). Further observations are planned.
We thank the VLA staff for scheduling and executing these observations"
GCN Circular 37159
Subject
GRB 240809A : RAPAS follow-up observations
Date
2024-08-12T21:51:25Z (a year ago)
Edited On
2024-08-12T22:25:05Z (a year ago)
From
Thierry Midavaine at GRANDMA <thierrymidavaine@sfr.fr>
Edited By
Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
Via
Web form
Thierry Midavaine on behalf of the RAPAS network reports (#1) :
P. Martinez and C. Latgé [1], M. Serrau [2] and A. Leroy [3] observed the Gamma-Ray Burst GRB240809A (Evans et al. GCN 37110 ; Want et al. GCN 37113) using [1] ADAGIO N 820mm telescope at Belesta Observatory (IAU A05) equiped with a Moravian CMOS camera, [2] SC 300mm telescope at Vidauban [A77] equiped with a QHYCCD CMOS camera and [3] SC 350mm telescope at Madagascar equiped with a ZWO ASI CMOS camera. [1] and [2] are equiped with the set of 3 RAPAS filters meeting the Gaia G, Gbp and Grp photometric bands. The FITS files are reduced with the Gaia photometric catalog in respective spectral bands.
The afterglow is detected RA(J2000) = 5h 50m 10.55s ; Dec(J2000) = -02d 19' 03.3" [1]
MJD (mid) Gaia filter band mag.(Gaia) RAPAS station
60531.66128 G 19.75 ± 0.14 [3]
60531.86667 Grp 20.48 ± 0.60 [1]
60531.86736 G 20.52 ± 0.47 [2]
60531.87778 Gbp 20.10 ± 0.32 [1]
60531.89444 G 20.58 ± 0.19 [1]
RAPAS ( https://proam-gemini.fr/rapas/ ) is a new ProAm collaboration funded by Paris Observatory, delivering to a network of french amateur observatories a set of 3 filters meeting the Gaia spectral bands. This network is dedicated to deliver data in the Gaia photometric system on selected astrophysical alerts by Astro-COLIBRI ( https://astro-colibri.com/ ) or from Gaia alerts.
GCN Circular 37162
Subject
GRB 240809A: ATA radio non-detection
Date
2024-08-12T23:39:16Z (a year ago)
From
Tanmoy Laskar at U of Bath <tanmoylaskar@gmail.com>
Via
legacy email
C. Christy (University of Arizona), W. Farah (SETI Institute), T. Laskar
(University of Utah), K. D. Alexander (University of Arizona), G. Schroeder
(Northwestern University), C. Peña (University of Utah), A. Pollak (SETI
Institute), A. Siemion (SETI Institute), E. Berger (Harvard University), R.
Chornock (UC Berkeley), W. Fong (Northwestern University), R. Margutti (UC
Berkeley), and P. Schady (University of Bath) report on behalf of a larger
collaboration:
"We observed GRB 240809A (Evans et al., GCN 37110) with the Allen Telescope
Array (ATA) beginning on 2024 August 09 23:25 UTC (14.9 h after the burst)
at 5GHz and 8GHz. In our preliminary analysis, we do not detect any radio
emission at or near the X-ray and optical position (Evans et al., GCN
37110) or radio position (Christy et al., GCN 37158) to a 3-sigma limit of
~0.9mJy at 5GHz and ~2.0mJy at 8GHz.
We thank the ATA staff for quickly scheduling these observations"
GCN Circular 37167
Subject
GRB 240809A: Correction to the VLA source position in GCN 37158
Date
2024-08-13T02:57:53Z (a year ago)
From
Tanmoy Laskar at U of Utah <tanmoylaskar@gmail.com>
Via
legacy email
C. Christy (University of Arizona), T. Laskar (University of Utah), K. D.
Alexander (University of Arizona), G. Schroeder (Northwestern University),
C. Peña (University of Utah), E. Berger (Harvard University), R. Chornock
(UC Berkeley), W. Fong (Northwestern University), R. Margutti (UC
Berkeley), and P. Schady (University of Bath) report on behalf of a larger
collaboration:
"The declination of the VLA radio counterpart of GRB 240809A given in GCN
37158 is incorrect. The correct source position is:
RA (J2000) = 15h 50m 10.5s
Dec (J2000) = -02d 19' 3.4"
with a (statistical) uncertainty of 0.2" in each coordinate. We apologize
for any confusion caused."
GCN Circular 37194
Subject
GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
Date
2024-08-16T19:54:06Z (10 months ago)
From
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com>
Via
Web form
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
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:
Following the Swift trigger no. 1247745 (GCN 37110 P. A. Evans (U Leicester), R. A. J. Eyles-Ferris (U Leicester),K. L. Page (U Leicester) and A. Tohuvavohu (U Toronto) report on
behalf of the Neil Gehrels Swift Observatory Team) from the Swift Burst Alert Telescope (BAT), we pointed at the coordinates RA(J2000)=15h 50m 12s: Dec(J2000)=-02d 19' 15" and started our observations with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy.
Member of:
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
The observations started at 19:25 UT of 2023/08/09, after about 11 hours after the GRB trigger, with clear sky, with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 48 unfiltered images of 60 sec .
Start End Rlim
19:25:37 UT 20:35:28 UT 20.5
All images, calibrated with masterdark and masterflat have been measured with Thycho Tracker software
We have detected a faint source at the enhanced position reported by Swift-XRT teamat following position
RA (J2000.0) 15 50 10.54
Dec (J2000.0) -02 19 05.3
with the following photometry and astrometry:
GRB 240809A 15 50 10.54 -02 19 05.3 20.0 C82
Magnitudes were estimated with the GAIA DR2 cat. and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular 37244
Subject
GRB 240809A: Mondy and AbAO Optical Observations
Date
2024-08-23T11:19:52Z (10 months ago)
From
Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>
Via
legacy email
S. Belkin (HSE, IKI), N. Pankov (HSE, IKI), E. Klunko (ISTP), R. Ya.
Inasaridze (AbAO), A. Pozanenko (IKI) report on behalf of GRB-IKI-FuN:
We observed the field of GRB 240809A, detected by Swift (Evans et al., GCN
37110) and SVOM (Wang et al., GCN 37113), using the AZT-33IK 1.5-meter
telescope at the Sayan Observatory (Mondy) and the AS-32 0.7-meter
telescope at the Abastumani Observatory (AbAO). The observations began on
2024-08-09 at 13:54:52 (UT) and 17:27:38 (UT), respectively, i.e., about
0.2 and 7 hours after the Swift trigger. The preliminary photometry of the
optical counterpart (Evans et al., GCN 37110; Dubay et al., GCN 37114;
Jiang et al., GCN 37116; Gottumukkala et al., GCN 37122; Shilling et al.,
GCN 37123; Mohan et al., GCN 37125; Zheng & Filippenko, GCN 37127;
Schneider et al., GCN 37129; Quadri et al., GCN 37131; Brivio et al., GCN
37132; Midavaine et al., GCN 37159; Ruocco et al., GCN 37194) is provided
below:
Date UT Start t-T0 Exp. Filter OT Err. UL Telescope
(mid, days) (s) (3sigma)
2024-08-09 13:54:52 0.24228 49*60 R 19.45 0.05 22.3 AZT-33IK
2024-08-09 17:27:38 0.37302 44*60 R n/d n/d 20.0 AS-32
The magnitudes were calibrated using nearby comparison stars from the
USNO-B1.0 catalog (R2 magnitudes). No correction was made for the Galactic
extinction toward the GRB, corresponding to E(B-V) = 0.213 (S&F 2011). The
optical light curve is well fitted by a power-law model with an index of
-1.3, which is typical for GRBs.