GRB 240825A
GCN Circular 37273
Subject
GRB 240825A: Fermi GBM Final Real-time Localization
Date
2024-08-25T16:03:37Z (a year 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 15:53:00 UT on 25 Aug 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240825A (trigger 746293985.085054 / 240825662).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 341.6, Dec = 5.9 (J2000 degrees, equivalent to J2000 22h 46m, 5d 54'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 47.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240825662/quicklook/glg_skymap_all_bn240825662.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240825662/quicklook/glg_healpix_all_bn240825662.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240825662/quicklook/glg_lc_medres34_bn240825662.gif
GCN Circular 37274
Subject
GRB 240825A: Swift detection of a burst with a bright optical counterpart
Date
2024-08-25T16:04:17Z (a year ago)
From
David Palmer at LANL <palmer@lanl.gov>
Via
email
R. Gupta (NASA GSFC), R. Brivio (INAF-OAB), S. Dichiara (PSU),
M. Ferro (INAF-OAB), J. A. Kennea (PSU), K. L. Page (U Leicester),
D. M. Palmer (LANL) and T. Sbarrato (INAF-OAB) report on behalf of the
Neil Gehrels Swift Observatory Team:
At 15:52:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 240825A (trigger=1250617). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 344.551, +1.036 which is
RA(J2000) = 22h 58m 12s
Dec(J2000) = +01d 02' 10"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a bright complex peak
structure with a duration of at least 10 sec. The peak count rate
was ~160k counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 15:54:22.9 UT, 83.1 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 344.5691, 1.0253 which is equivalent to:
RA(J2000) = 22h 58m 16.58s
Dec(J2000) = +01d 01' 31.1"
with an uncertainty of 12.3 arcseconds (radius, 90% containment). This
location is 75 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 92 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 22:58:17.26 = 344.57192
DEC(J2000) = +01:01:36.7 = 1.02686
with a 90%-confidence error radius of about 0.74 arc sec. This position is 11.6
arc sec. from the center of the XRT error circle. The estimated magnitude is
15.57 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.063.
Burst Advocate for this burst is R. Gupta (rahulbhu.c157 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 37275
Subject
GRB 240825A: Nanshan/HMT optical afterglow observations
Date
2024-08-25T16:58:28Z (a year ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Via
Web form
S.Q. Jiang, X. Liu, J. An, Z.P. Zhu, S.Y. Fu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report on behalf of a large collaboration:
We observed the field of GRB 240825A detected by Swift (Gupta et al., GCN 37274) and Fermi (Fermi GBM team, GCN 37273), using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. A series of 60 s and 200 s images were obtained in the clear filter, starting at 16:06:38 UT on 2024-08-25, i.e., 819 s after the Swift/BAT trigger.
An uncatalogued and fading optical source is detected in our individual images at coordinates
R.A. (J2000) = 22:58:17.265
Dec. (J2000) = +01:01:36.83
with an uncertainty of ~ 0.4 arcsec, being consistent with the Swift/UVOT position (Gupta et al., GCN 37274). The source has ~ 17.0 mag in our first image, calibrated with Gaia G-band and not corrected for Galactic extinction. We thus think the source is the optical afterglow of the burst.
Observations are still ongoing.
GCN Circular 37276
Subject
GRB 240825A: Skynet Optical Afterglow observations
Date
2024-08-25T16:58:32Z (a year ago)
From
Dylan Dutton at UNC Chapel Hill <ddutton59@gmail.com>
Via
Web form
Dylan Dutton, Megan Dubay, Donovan Schlekat, Ruide Fu, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, John Kennewall, Arie Veever, and Daryl Janzen report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill.
We observed the field of GRB 240825A with the PROMPT telescope located in Meckering, Australia. The observation began at 15:55:45 UT on August 25 2024, roughly 150 seconds post-trigger by the Swift-BAT instrument.
We detect a bright object with coordinates consistent with the Swift UVOT candidate (GCN 37274) at:
R.A. (J2000): 22:58:17.287
Dec. (J2000): 01:01:37.121
The object is fading with a temporal index of roughly 1.1 and appears to be very red. We detect the object in the V, R, and I band. The initial I-band detection photometry is reported below.
Tmid - T0 | Telescope | Filter | Exposure Duration | Mag | Mag Error
360s | PROMPT-MO | I | 14s | 14.955 | 0.035
Our images have been calibrated using stars from the APASS catalog. Additional Skynet observations are ongoing.
GCN Circular 37277
Subject
GRB 240825A: AKO Optical Afterglow Detection
Date
2024-08-25T17:37:42Z (a year ago)
From
Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>
Via
legacy email
Mohammad Odeh (Al-Khatim Observatory, AKO, operated by the International
Astronomical Center in Abu Dhabi, UAE), and Nidhal Guessoum (American
University of Sharjah, UAE), report:
We observed the field of GRB 240825A detected by Fermi (Fermi GBM team, GCN
37273) and Swift (Gupta et al., GCN 37274), with our 0.36m f/7.7 robotic
telescope. The observation started on 25 August 2024 at 16:48 (UT), 55
minutes from the trigger.
We obtained multiple 180-sec exposures in Ic filter. We clearly detected the
optical afterglow at:
R.A. (J2000): 22:58:17.3
Dec. (J2000): +01:01:36.4
Our detection is consistent with the results of (Jiang et al., GCN 37275;
and Dutton et al., GCN 37276).
The following observation was calculated using Atlas catalogue as a
reference:
----------------------------------------------------------------------------
-
ObsTime (mid), Exposure (sec), Filter, Mag
----------------------------------------------------------------------------
-
2024-08-25T17:08:55Z, 13 x 180s (stacked), Ic, 17.6 +/- 0.16
----------------------------------------------------------------------------
-
The magnitude is not corrected for galactic extinction.
GCN Circular 37278
Subject
GRB 240825A: 1.6m Mephisto multi-band detection
Date
2024-08-25T18:03:57Z (a year ago)
From
Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn>
Via
Web form
Jinghua Zhang (SWIFAR, YNU), Guowang Du (SWIFAR, YNU), Helong Guo (SWIFAR, YNU), Brajesh Kumar (SWIFAR, YNU), Tao Wang (SWIFAR, YNU), Zhenfei Qin (SWIFAR, YNU), Yicheng Jin (SWIFAR, YNU), Xingzhu Zou (SWIFAR, YNU), Yu Pan (SWIFAR, YNU), Xinlei Chen (SWIFAR, YNU), Yuan Fang (SWIFAR, YNU), Xuhui Han (NAOC), Pinpin Zhang (NAOC), Liping Xin (NAOC), Chao Wu (NAOC), Yuanpei Yang (SWIFAR, YNU), Xinzhong Er (SWIFAR, YNU), Xiangkun Liu (SWIFAR, YNU), Xiaowei Liu (SWIFAR, YNU) report on behalf of Mephisto Team:
Simultaneous multi-band photometric observations of the Swift GRB 240825A (Gupta et al., GCN 37274), Fermi (Fermi GBM team, GCN 37273) was performed with 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. Mephisto was triggered immediately after the notice and the observations were started at (UTC) 2024-08-25 15:55:07 in moderate sky conditions. Multiple frames in uvgriz -bands were acquired. The OT (Gupta et al., GCN 37274, Jiang et al., GCN 37275, Dutton et al., GCN 37276, Odeh et al., 37277) is clearly detected in each frame. The preliminary magnitudes in initial frames are below:
Time (2024-08-25 UT) Filter Exp (sec) Mag (AB)
15:55:07 v 180 16.73 +- 0.01
15:55:07 r 60 14.46 +- 0.01
15:55:07 z 120 13.61 +- 0.01
16:08:10 u 180 19.15 +- 0.09
16:08:10 g 60 17.49 +- 0.03
16:08:10 i 120 16.42 +- 0.01
-----------------------------------------------------------------------------------------------------
Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21.
-----------------------------------------------------------------------------------------------------
GCN Circular 37279
Subject
Swift GRB 240825A: Global MASTER-Net observations report
Date
2024-08-25T18:08:32Z (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-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) was pointed to the Swift GRB 240825A ( R. Gupta et al., GCN 37274) errorbox 7109 sec after notice time and 7126 sec after trigger time at 2024-08-25 17:51:46 UT, with upper limit up to 18.0 mag. Observations started at twilight. The observations began at zenith distance = 74 deg. The sun altitude is -14.2 deg.
The galactic latitude b = -51 deg., longitude l = 75 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2574610
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
7217 | MASTER-Tavrida | C | 180 | 16.8 |
7409 | MASTER-Tavrida | C | 180 | 17.4 |
7602 | MASTER-Tavrida | C | 180 | 17.7 |
7802 | MASTER-Tavrida | C | 180 | 18.0 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 37280
Subject
GRB 240825A: GMG Optical Observation
Date
2024-08-25T18:13:19Z (a year ago)
Edited On
2024-08-25T20:36:57Z (a year ago)
From
Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi@ynao.ac.cn>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi@ynao.ac.cn>
Via
Web form
R.-Z. Li, B.-T. Wang, F.-F. Song, J. Mao, Y.-X. Xin, and J.-M. Bai (YNAO, CAS) report:
We observed the field of GRB 240825A (Gupta et al., GCN 37274, T0 at 2024-08-25T15:52:59) using the GMG-2.4m telescope at the Lijiang Observatory. The observation began at 2024-08-25T17:42:38, about 1.83 hours after the trigger.
The optical counterpart of GRB 240825A, not visible in the Pan-STARRS1 r-band image, was clearly detected at the coordinates (J2000):
RA = 22h58m17.26s
DEC = +01d01'36.7"
, with a positional uncertainty of 0.5" or better. The position is consistent with Swift/UVOT (GCN 37274), Nanshan/HMT (GCN 37275), Skynet (GCN 37276) and AKO (GCN 37277).
The preliminary analysis results are shown as follows:
+----------------+------------+----------+--------------+----------------+
| Tmid-T0 [hr] | Exp. [s] | Filter | Mag | 5-sigma U.L. |
+================+============+==========+==============+================+
| 1.91 | 600 | R | 18.97 ± 0.04 | 21 |
+----------------+------------+----------+--------------+----------------+
The given magnitudes are derived based on calibration against Pan-STARRS1 field stars, and are not corrected for the expected Galactic foreground extinction, corresponding to a reddening of E(B-V) = 0.053 mag in the direction of the optical counterpart (Schlafly & Finkbeiner 2011).
The optical spectroscopic observation is ongoing, but there are thin clouds in the sky.
We acknowledge the staff at the Lijiang Observatory for their efforts in conducting the observation. In particular, we extend our gratitude to the on-duty observers for promptly resolving the instrumental cooling problems with the GMG-2.4m telescope that arose during the night.
GCN Circular 37283
Subject
Fermi GRB 240825A: Global MASTER-Net observations report
Date
2024-08-25T20:30:46Z (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-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 240825A ( Fermi GBM team, GCN 37273) errorbox 15929 sec after notice time and 15970 sec after trigger time at 2024-08-25 20:19:11 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 46 deg. The sun altitude is -32.2 deg.
The galactic latitude b = -45 deg., longitude l = 77 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2574669
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
16001 | 2024-08-25 20:19:11 | MASTER-Tavrida | (22h 43m 16.81s , +04d 47m 27.0s) | C | 60 | 17.9 |
16001 | 2024-08-25 20:19:11 | MASTER-Tavrida | (22h 43m 15.65s , +04d 52m 02.2s) | C | 60 | 18.1 |
16079 | 2024-08-25 20:20:29 | MASTER-Tavrida | (22h 51m 24.13s , +04d 47m 44.8s) | C | 60 | 18.2 |
16080 | 2024-08-25 20:20:29 | MASTER-Tavrida | (22h 51m 22.93s , +04d 52m 18.7s) | C | 60 | 18.5 |
16154 | 2024-08-25 20:21:44 | MASTER-Tavrida | (22h 46m 19.62s , +06d 05m 31.5s) | C | 60 | 17.8 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 37287
Subject
GRB 240825A: LCO optical observations
Date
2024-08-25T22:27:56Z (a year ago)
From
luca.izzo@inaf.it
Via
Web form
L. Izzo (INAF-OACn and DARK/NBI) and D. B. Malesani (DAWN/NBI and Radboud Univ.) report:
We observed the field of GRB 240825A (Gupta et al., GCN #37274) with the Sinistro instrument mounted on the 1-m telescope of the LCO network, located in Sutherland, South Africa. Observations started on 2024 August 25 at 20:43:23 UT (4.85 hr after the GRB trigger). We obtained a series of 3x120 s images in the SDSS-r filter and 5x120s images in the PS1-z filter.
The optical afterglow counterpart is clearly detected at a location consistent with the source reported by the Swift-UVOT (Gupta et al., GCN #37274) and by other optical observations (Jiang et al., GCN #37275; Dutton et al., GCN #37276; Odeh et al., GCN #37277, Li et al., GCN #37280).
We measure preliminary magnitudes of r = 20.1 +/- 0.1 mag (AB), and z = 19.3 +/- 0.1 mag (AB), calibrated against nearby stars from the Pan-STARRS catalog.
We also notice the presence of an archival source, with an offset of <1" from the GRB optical afterglow, with magnitude r = 22.7 mag (AB) in the Pan-STARRS DR1 catalog. This is a potential host galaxy of GRB 240825A, and is clearly reported in the Legacy Survey DR10 images as well.
This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 101004719.
GCN Circular 37288
Subject
GRB 240825A: Fermi-LAT detection
Date
2024-08-25T22:58:40Z (a year ago)
From
Rahul Gupta at NASA GSFC <rahulbhu.c157@gmail.com>
Via
email
N. Di Lalla (Stanford University), R. Gupta (NASA GSFC), and A. Holzmann
(DF, University of Buenos Aires, Argentina) report on behalf of the
Fermi-LAT Collaboration:
On Aug 25, 2024, Fermi-LAT detected high-energy emission from GRB 240825A,
which was also detected by Fermi-GBM (trigger 746293985 / 240825662, GCN
37273) and Swift-BAT (Gupta et al., GCN 37274).
The best LAT on-ground location is found to be:
RA, Dec = 344.56, 1.04 (J2000)
with an error radius of 0.07 deg (90 % containment, statistical error only).
This was 52 deg from the LAT boresight at the time of the GBM trigger: T0 =
15:53:00 UT.
The data from the Fermi-LAT show a significant increase in the event rate
that is spatially and temporally correlated with the GBM emission with high
significance. The photon flux above 100 MeV in the time interval 0-2000 s
after the GBM trigger is (2.9 +/- 0.2) E-5 ph/cm2/s. The estimated photon
index above 100 MeV is -2.65 +/- 0.09.
The highest-energy photon is a 40 GeV event which is observed ~ 240 seconds
after the GBM trigger.
The Fermi-LAT point of contact for this burst is Francesco Longo (
francesco.longo@ts.infn.it).
The Fermi-LAT is a pair conversion telescope designed to cover the energy
band from 20 MeV to greater than 300 GeV. It is the product of an
international collaboration between NASA and DOE in the U.S. and many
scientific institutions across France, Italy, Japan and Sweden.
GCN Circular 37289
Subject
GRB 240825A: MASTER optical counterpart observation
Date
2024-08-25T23:03:31Z (a year ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
legacy email
V.Lipunov (MSU), D.Buckley (SAAO),
K.Zhirkov, I.Gorbunov, P.Balanutsa, G.Antipov, A.Kuznetsov, N.Tiurina,
E.Gorbovskoy, D.Vlasenko, Ya.Kechin, Yu.Tselik, V..Senik (Lomonosov MSU,SAI,PhysicsDepartment),
O.Gress, N.Budnev(ISU),
A.Sosnovskij (Crimean Astrophysical Observatory, RAS),
C.Francile. F. Podesta, R.Podesta (Observatorio Astronomico Felix AguilarOAFA),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
MASTER Global robotic net (http://observ.pereplet.ru Lipunov et al.,2010,Advances in Astronomy,2010,30L)
started observation (Lipunov et al. GCN 37279) of Swift GRB240825A
(R.Gupta et al. GCN 37274) in MASTER-SAAO and MASTER-Tavrida (rain in MASTER-Amur, -Tunka and -Kislovodsk).
The optical transient, discovered by Swift and also observed by
Nanshan HMT / Jiang et al., GCN #37275; Skynet / Dutton et al., GCN #37276; AKO / Odeh et al., GCN #37277,
Mephisto / Zhang et al. GCN 37278, GMG / Li et al., GCN #37280)
was detected at MASTER-SAAO images started 2024-08-25 18:05:12 with unfiltered m_OT=20.1 (mlim=21.0).
There are several SDSS objects inside 3" from Swift-UVOT position in VIZIER database,
the closest is SDSS galaxy (also visible in Pan-STARRs images) in 0.07" with rmag=23.095 https://skyserver.sdss.org/dr9/en/tools/quicklook/quickobj.asp?id=1237663785264350187 .
Observations and reduction will be continued.
GCN Circular 37290
Subject
GRB 240825A: Enhanced Swift-XRT position
Date
2024-08-25T23:19:53Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1085 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 240825A, 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 = 344.57200, +1.02675 which is equivalent
to:
RA (J2000): 22h 58m 17.28s
Dec (J2000): +01d 01' 36.3"
with an uncertainty of 2.7 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 37291
Subject
GRB 240825A: Montarrenti Observatory optical observations
Date
2024-08-25T23:40:44Z (a year ago)
From
Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini@iol.it>
Via
Web form
S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy, part of UAI/SSV-GRB section), M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy) and B. De Simone (Università degli Studi Di Salerno) report:
We observed the field of GRB 240825A (Swift trigger 1250617, Gupta et al., GCN 37274; Fermi/GBM trigger 746293985.085054 / 240825662, GCN 37273) with the automated and remoted 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88).
The observations were started at 2024-08-25 21:12:38 UT (approximately 5.5 hours after burst) stacking 50x40s Rc-band CCD images.
The OT was detected at the following position:
RA (J2000.0) 22h 58m 17.26s +/-0.05
Decl. (J2000.0) +01° 01' 37.5" +/-0.13
Preliminary photometry was obtained using nearby PanSTARRS stars as follows:
MJD Filter Mag. Err.
60548.39591 Rc 19.81 +/-0.10
Magnitude was calibrated with the nearby PanSTARRS stars converted using Lupton (2005) equations. No correction for galactic dust extinction was applied.
Our observations are consistent with other already reported (Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN 37277; Zhang et al., GCN 37278; Li et al., GCN 37280; Izzo et al., GCN 37287).
Further observations are ongoing.
GCN Circular 37292
Subject
GRB 240825A: SVOM/C-GFT optical observations
Date
2024-08-26T03:35:03Z (a year ago)
Edited On
2024-08-26T13:41:45Z (a year ago)
From
Chao Wu at NAOC <wuchao.lamost@gmail.com>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Chao Wu at NAOC <wuchao.lamost@gmail.com>
Via
Web form
SVOM/C-GFT team: Chao Wu (NAOC), Zhe Kang (CHO)，Liping Xin(NAOC),Xuhui Han(NAOC),Pinpin Zhang (NAOC)，Xiaomeng Lu (NAOC), Zhenwei Li (CHO)，You Lv (CHO)，Ruosong Zhang (NAOC)，Yujie Xiao(NAOC)
SVOM JSWG: Jian-Yan Wei (NAOC, China), Bertrand Cordier (CEA, F), Shuang-Nan Zhang (IHEP, CN), Stephane Basa (LAM, F), Jean-Luc Attéia (IRAP, F), Arnaud Claret (CEA, F), Zi-Gao Dai (USTC, CN), Frederic Daigne (IAP, F), Jin-Song Deng (NAOC, CN), Andrea Goldwurm (APC, F), Diego Götz (CEA, F), Xu-Hui Han (NAOC, CN), Cyril Lachaud (APC, F), En-Wei Liang (GXU, CN), Yu-Lei Qiu (NAOC, CN), Susanna Vergani (Obs.Paris, F), Jing Wang (NAOC, CN), Chao Wu(NAOC, CN), Li-Ping Xin (NAOC,CN), Bing Zhang (UNLV, CN)
We observed the burst GRB 240825A (Swift trigger 1250617, Gupta et al., GCN 37274; Fermi/GBM trigger 746293985.085054 / 240825662, GCN 37273) on 15:54:05 UT, Aug. 25, 2024, about 65 seconds after the Swift trigger with C-GFT (Chinese Ground Follow-up Telescope in SVOM mission) in System Test Mode (STM). C-GFT is located at Jilin (long.=126.33 deg, lat.=43.8243778 deg), Changchun Observatory, National Astronomical Observatories, CAS. It has FOV of 1.28 deg X 1.28 deg with a 4k*4k CMOS detector mounted on the primary focus of 1.2-meter-aperure telescope.
A series of g,r and i band images were obtained. The exposure time was 10 seconds for each frame. The optical optical afterglow reported (Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN 37277; Zhang et al., GCN 37278; Li et al., GCN 37280; Izzo et al., GCN 37287, Lipunov GCN 37289, Leonini GCN 37291) are clearly detected in our images.
The preliminary photometric results are listed as following,
-----------------------------------------------------------
Filter (t-T0) sec mag +/- mag_error
g 65 -> 2555 14.56 +/- 0.02 -> 19.18 +/- 0.20
r 206 -> 2088 14.56 +/- 0.02 -> 19.33 +/- 0.15
i 294 -> 2162 16.79 +/- 0.02 -> 19.33 +/- 0.15
The photometry was calibrated with nearby PS1 catalogs. More detailed analysis is continuing.
We thank the observation assistant Chunlei Guo at Jilin observatory for their excellent support.
The SVOM/C-GFT point of contact for this burst is: Chao Wu (cwu@bao.ac.cn)
GCN Circular 37293
Subject
GRB 240825A: VLT/X-shooter redshift
Date
2024-08-26T08:44:45Z (a year ago)
From
Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo@ucd.ie>
Via
Web form
A. Martin-Carrillo (UCD), B. Schneider (MIT), G. Pugliese (API-UvA), L. Izzo (INAF-OACn & DARK/NBI), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Saccardi (GEPI/Obs. de Paris), T. Laskar (Utah), J. F. Agui Fernandez (CAHA) and S. D. Vergani (GEPI/Obs. de Paris) report on behalf of the Stargate collaboration:
We observed the optical counterpart of the Swift/Fermi GRB 240825A (Gupta et al., GCN 37274; Fermi GBM team, GCN 37273; Di Lalla et al., GCN 37288) using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, and consist of 4 exposures of 1200 s each. The observation was carried out under good seeing (1”) with mid-time 03:03:55 UT on 2024 August 26 (~11.2 hours after the Swift trigger).
In a 60 s image taken with the acquisition camera, we clearly detect the optical afterglow (Gupta et al., GCN 37274; Jiang et al. GCN 37275; Dutton et al. GCN 37276; Odeh et al. GCN 37277; Zhang et al. GCN 37278; Li et al. GCN 37280; Izzo & Malesani, GCN 37287; Lipunov et al. GCN 37289; Leonini et al. GCN 37291; Wu et al. GCN 37292), for which we measure an AB magnitude r = 20.8 (calibrated against nearby stars from the Pan-STARRS catalogue).
In a preliminary reduction of the spectra, we clearly detect the continuum over the entire wavelength range. From detection of multiple absorption features, which we interpret as due to Fe II, Fe II*, Mn II, Mg II, Mg I, Ca II and Na I, we infer a common redshift of z = 0.659. We also detect bright emission lines ([O II] and [O III] doublets, Halpha and Hbeta) at a consistent redshift, which we interpret as being due to the GRB host galaxy (Izzo & Malesani, GCN 37287). We conclude that GRB 240825A is at z = 0.659.
We acknowledge expert support from the ESO staff in Paranal, in particular Matias Jones.
GCN Circular 37294
Subject
GRB 240825A: Swift-XRT refined Analysis
Date
2024-08-26T10:43:16Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR),
V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), S. Dichiara
(PSU), J.A. Kennea (PSU) and P.A. Evans report on behalf of the
Swift-XRT team:
We have analysed 8.6 ks of XRT data for GRB 240825A, from 71 s to 56.6
ks after the BAT trigger. The data comprise 1.2 ks in Windowed Timing
(WT) mode (the first 10 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=3.13 (+0.24, -0.21). At T+119 s the decay
flattens to an alpha of 0.83 (+/-0.06). The light curve breaks again at
T+406 s to a decay with alpha=1.121 (+0.019, -0.028), and again at
T+1288 s s to alpha=1.52 (+6.48, -0.05), before a final break at
T+6251 s s after which the decay index is 1.25 (+0.06, -0.08).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.661 (+/-0.017). The
best-fitting absorption column is 1.09 (+/-0.04) x 10^22 cm^-2, at a
redshift of 0.659, in addition to the Galactic value of 5.3 x 10^20
cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index
of 1.76 (+/-0.09) and a best-fitting absorption column of 9.1 (+1.6,
-1.4) 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 (5.9
x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Galactic foreground: 5.3 x 10^20 cm^-2
Intrinsic column: 9.1 (+1.6, -1.4) x 10^21 cm^-2 at z=0.659
Photon index: 1.76 (+/-0.09)
If the light curve continues to decay with a power-law decay index of
1.25, the count rate at T+24 hours will be 0.093 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.1 x
10^-12 (5.5 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01250617.
This circular is an official product of the Swift-XRT team.
GCN Circular 37295
Subject
GRB 240825A: REM detection of the optical/NIR afterglow
Date
2024-08-26T12:03:35Z (a year ago)
From
Riccardo Brivio <riccardo.brivio@inaf.it>
Via
Web form
R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 240825A (Gupta et al., GCN 37274; Fermi GBM team, GCN 37273; Di Lalla et al., GCN 37288) 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 and K bands, starting on 2024 Aug 26 at 00:28:43 UT (i.e. about 8.6 hours after the Swift trigger) and lasted for about 1 hour.
The optical afterglow is detected in the r band at a position coincident with that reported by Swift-UVOT (Gupta et al., GCN 37274) and other optical observations (Jian et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN 37277; Zhang et al., GCN 37278; Li et al., GCN 37280; Izzo & Malesani, GCN 37287). The NIR afterglow is detected in the J band at a position consistent with the optical counterpart.
From preliminary photometry, we derive the following magnitudes:
r = 20.5 +/- 0.3 (AB; calibrated against the Pan-STARRS catalogue)
at a mid-time of t-t0 ~ 9.1 hours after the trigger,
J = 17.7 +/- 0.3 (Vega; calibrated against the 2MASS catalogue)
at a mid-time of t-t0 ~ 9.2 hours after the trigger.
GCN Circular 37296
Subject
GRB 240825A: Swift/UVOT Detection
Date
2024-08-26T12:54:52Z (a year ago)
Edited On
2024-08-26T13:40:13Z (a year ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Rahul Gupta at NASA GSFC <rahulbhu.c157@gmail.com>
Via
email
N. P. M. Kuin (UCL-MSSL) and R. Gupta (NASA GSFC)
report on behalf of the Swift/UVOT team:The Swift/UVOT began settled
observations of the field of
GRB 240825A 93 s after the BAT trigger (Gupta et al.,
GCN Circ. 37274). A source consistent with the XRT
position (Evans et al. GCN Circ. 37290 is detected
in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 22:58:17.26 = 344.57192 (deg.)
Dec (J2000) = +01:01:36.9 = 1.02691 (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 93 243 147 15.58 +/- 0.02
v 807 827 20 17.02 +/- 0.20
b 561 580 20 17.54 +/- 0.15
u 305 555 246 16.93 +/- 0.05
w1 684 1281 58 18.55 +/- 0.30
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.063 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 37298
Subject
GRB 240825A: AstroSat CZTI detection of the long bright burst
Date
2024-08-26T15:39:53Z (a year ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
J. Joshi (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 a bright long-duration GRB 240825A which was also detected by Fermi/GBM (Fermi GBM team, GCN Circ. 37273), Swift/BAT (R. Gupta et al., GCN Circ. 37274), and INTEGRAL/SPI-ACS (Trigger 10871).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-08-25 15:53:01.50 UTC. Due to the extremely bright nature of the GRB, all four quadrants of CZT detectors were saturated. This affects the total counts and peak counts reported. The measured peak count rate associated with the burst is 2791 (+90, -96) counts/s above the background in the combined data of three quadrants (out of four), with a total of 6260 (+168, -178) counts. The local mean background count rate was 251 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 6.2 (+0.9, -0.8) s. In the preliminary analysis, we find 600 Compton events associated with this event.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-08-25 15:53:01.57 UTC. The measured peak count rate associated with the burst is 9409 (+168, -183) counts/s above the background in the combined data of all quadrants, with a total of 24203 (+406, -428) counts. The local mean background count rate was 1473 (+7, -9) counts/s. We measure a T90 of 6.1 (+0.7, -0.6) 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 37299
Subject
GRB 240825A: AKO Optical Follow-Up Observations
Date
2024-08-26T15:40:54Z (a year ago)
From
Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>
Via
legacy email
Mohammad Odeh (Al-Khatim Observatory, AKO, operated by the International
Astronomical Center in Abu Dhabi, UAE), and Nidhal Guessoum (American
University of Sharjah, UAE), report:
We followed up our observations (Odeh & Guessoum, GCN 37277) of GRB 240825A
(Fermi GBM team, GCN 37273; Gupta et al., GCN 37274; Swift-XRT team, GCN
37290), with our 0.36m f/7.7 robotic telescope, performing 5 observations
between 25 August 2024 at 16:48 UT (0.92 hour after the trigger) and 25
August 2024 at 18:57 UT (3.1 hours after the trigger).
We obtained multiple 180-sec exposures in Ic filter. The optical afterglow
was fading:
Our measurements are consistent with other reports (Jiang et al., GCN 37275;
Lipunov et al., GCN 37279; and Wei et al., GCN 37292).
The following magnitudes were determined using the Atlas catalogue as a
reference:
----------------------------------------------------------------------------
ObsTime (mid), t-T0 (hour), Exposure (sec), Filter, Mag & Mag_Err
----------------------------------------------------------------------------
2024-08-25T16:59Z, 1.1, 7x180s (stacked), Ic, 17.3 +/- 0.15
2024-08-25T17:23Z, 1.5, 7x180s (stacked), Ic, 17.9 +/- 0.18
2024-08-25T17:48Z, 1.9, 7x180s (stacked), Ic, 18.1 +/- 0.13
2024-08-25T18:17Z, 2.4, 7x180s (stacked), Ic, 18.2 +/- 0.13
2024-08-25T18:42Z, 2.8, 7x180s (stacked), Ic, 18.4 +/- 0.17
----------------------------------------------------------------------------
The magnitudes were not corrected for galactic extinction.
GCN Circular 37300
Subject
GRB 240825A : MISTRAL/T193 OHP optical follow-up of the afterglow
Date
2024-08-26T15:52:26Z (a year ago)
From
Emeric Le Floc'h at CEA-Saclay <emeric.lefloch@cea.fr>
Via
Web form
E. Le Floc’h (CEA Paris-Saclay, DAp/AIM), C. Adami (LAM), B. Schneider (MIT), A. Saccardi (GEPI, Obs. De Paris), S. Basa (OSU Pytheas, LAM), M. Dennefeld (IAP), F. Schüssler (CEA Paris-Saclay, DPhP), report on behalf of the MISTRAL GRB collaboration :
We observed the field of GRB 240825A (Gupta et al., GCN 37274; Fermi GBM team, GCN 37273) with the MISTRAL instrument mounted on the 193cm telescope at Observatoire de Haute-Provence (France). Three exposures of 5min were obtained in the SDSS r’ band, for a total exposure time of 15min and an observation mid-time of 2024 August 25, ~22:40 UT (~6.85 hr after the GRB trigger).
The optical afterglow is clearly detected, at a position consistent with the counterpart reported earlier by other telescopes (e.g., Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN 37277, Li et al., GCN 37280, Izzo et al., GCN 37287; Lipunov et al. GCN.37289; Leonini et al. GCN 37291; Wu et al., GCN 37292; Martin-Carrillo et al., GCN 37293; Brivio et al., GCN 37295; Odeh, GCN 37299).
We obtain a magnitude of r’ = 20.63 +/- 0.03 mag (AB), calibrated against nearby stars from the Pan-STARRS catalog, and where the photometric uncertainty does not include any systematics. The photometry is not corrected for Galactic extinction.
We are grateful to Xavier Delfosse (IPAG) and we also thank the support from the Observatoire de Haute-Provence, in particular Jean-Pierre Troncin and Jérome Schmitt.
GCN Circular 37301
Subject
GRB 240825A: Fermi GBM Observation
Date
2024-08-26T16:12:52Z (a year ago)
From
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov>
Via
Web form
V. Sharma (NASA GSFC/UMBC), and C. Meegan (UAH) report on behalf of the
Fermi Gamma-ray Burst Monitor Team:
At 15:53:00 UT on 25 August 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240825A (trigger 746293985/240825662),
which was also detected Swift (R. Gupta et al. 2024, GCN 37274),
Fermi-LAT (N. Di Lalla et al. 2024, GCN 37288), and
VLT/X-shooter (A. Martin-Carrillo et al. 2024, GCN 37293).
The Final Real-time Localization (Fermi GBM Team 2024, GCN 37273)
is consistent with Swift and Fermi-LAT.
The angle from the Fermi LAT boresight is 52 degrees.
The GBM light curve many overlapping short pulses with a
duration (T90) of about 4 s (50-300 keV). The time-averaged
spectrum from T0+0.96 to T0+6.85 s best fit by a Band function
with Epeak = 442 +/- 8 keV, alpha = -0.82 +/- 0.01,
and beta = -2.22 +/- 0.02.
The event fluence (10-1000 keV) in this time interval is
(1.01 +/- 0.01)E-04 erg/cm^2. The 1-s peak photon flux measured
starting from T0+1.22 s in the 10-1000 keV band is 203 +/- 1 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 37302
Subject
Konus-Wind detection of GRB 240825A (bright/long)
Date
2024-08-26T17:10:30Z (a year 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 bright, long GRB 240825A (Fermi GBM detection:
Fermi GBM team, GCN 37273; Sharma & Meegan, GCN 37303;
Swift detection: Gupta et al., GCN 37274;
Fermi LAT detection: Di Lalla et al., GCN 37288;
AstroSat CZTI detection: Joshi al., GCN 37298)
triggered Konus-Wind (KW) at T0=57185.048 s UT (15:53:05.048).
The burst light curve shows a bright multi-peaked emission pulse,
which starts at ~T0 - 0.1 s, peaks around ~T0 + 0.256 s,
and has a total duration of ~2 s.
This pulse is followed by a weaker emission, which lasts
until ~T0 + 25 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/GRB240825_T57185/
As observed by Konus-Wind, the burst had
a fluence of (1.66 ± 0.08)x10^-4 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 0.256 s,
of (1.52 ± 0.07)x10^-4 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
A time-averaged spectrum (measured from T0 to T0+28.16 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.79 (-0.04,+0.05),
the high energy photon index beta = -2.10 (-0.8,+0.06),
the peak energy Ep = 403 (-37,+40) keV,
chi2 = 99/97 dof.
A spectrum near the peak count rate (measured from T0 to T0+0.512 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.30 (-0.11,+0.12),
the high energy photon index beta = -2.30 (-0.09,+0.08),
the peak energy Ep = 405 (-36,+41) keV,
chi2 = 68/63 dof.
Assuming the redshift z=0.659 (Martin-Carrillo et al., GCN 37253)
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 (2.00 ± 0.96)x10^53 erg,
the isotropic peak luminosity L_iso to (3.04 ± 0.14)x10^53 erg/s,
the rest-frame peak energy Ep,i,z to (670 ± 60) keV.
With the obtained estimates, GRB 240825A is inside 68% 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/GRB240825_T57185/GRB240825A_rest_frame.pdf
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.
GCN Circular 37303
Subject
GRB 240825A: PRIME near-infrared detection
Date
2024-08-26T17:12:41Z (a year ago)
Edited On
2024-08-26T21:15:09Z (a year ago)
From
Joe Durbak at UMD <gcn.joedurbak@gmail.com>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Joe Durbak at UMD <gcn.joedurbak@gmail.com>
Via
Web form
O. Guiffreda (UMD), J. Durbak (UMD), S. Atri (U Rome), A. S. Kutyrev (NASA/GSFC), E. Troja (U Rome), K. De (MIT), S. B. Cenko (NASA/GSFC)
Following the Swift BAT detection (GCN 37274), and Fermi GBM detection (GCN 37273), we observed the transient field in J and H filters with PRIME ~8 hours after FERMI & Swift detection.
At the position of the optical counterpart reported by Swift UVOT (GCN 37274), we detect an uncatalogued source in J and H bands. Using nearby VISTA Hemispherical Survey (VHS) stars for preliminary calibration we derive the following magnitudes, not corrected for Galactic extinction:
Filter | Mag(AB) | SNR | Seeing | Exp. time (s)
-------|--------------|------|--------|---------------
J | 18.9 +/- 0.2 | 17.5 | 2.1” | 600
H | 18.5 +/- 0.2 | 34.0 | 2.3” | 600
The J-band results are consistent with the REM detection of 17.7 +/- 0.3 Mag(Vega) (GCN 32795) taken an hour later.
Further observations are planned.
PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO) (Kutyrev et al. 2023, Yama et al. 2023).
We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations.
GCN Circular 37304
Subject
GRB 240825A: KAIT optical observations
Date
2024-08-26T17:49:29Z (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 240825A (Gupta et al., GCN 37274;
Fermi GBM team, GCN 37273) starting at 05:36 UT, Aug. 26th, about
13.73 hours after the bust. Observations were performed in the clear
(roughly R) filter, and the exposure time was 60s per image, with a
total of 31 images were obtained. We clearly detected the optical
afterglow (Gupta et al., GCN 37274; Jiang et al., GCN 37275; Dutton
et al., GCN 37276; Odeh et al., GCN 37277, Zhang et al., GCN 37278;
Li et al., GCN 37280, Izzo et al., GCN 37287; Lipunov et al., GCN
37289; Leonini et al., GCN 37291; Wu et al., GCN 37292; Martin-Carrillo
et al., GCN 37293; Brivio et al., GCN 37295; Kuin et al., GCN 37296;
Odeh et al., GCN 37299; Le Floc’h et al., GCN 37300; Guiffreda et al.,
GCN 37303) in our coadd image, which we measured its brightness of
20.8 +/- 0.2 mag at a mid time of ~14.04 hours after the burst,
calibrated to the Pan-STARRS1 catalog.
GCN Circular 37306
Subject
GRB 240825A: GMG Continued Optical Observation on the Second Night
Date
2024-08-27T02:34:35Z (a year ago)
From
wangbaiting@ynao.ac.cn
Via
Web form
B.-T. Wang, F.-F. Song, R.-Z. Li, J. Mao, Y.-X. Xin, and J.-M. Bai (YNAO, CAS) report:
We observed the field of GRB 240825A (Gupta et al., GCN 37274, T0 at 2024-08-25T15:52:59) for the second time using the GMG-2.4m telescope at the Lijiang Observatory. The observation began at 2024-08-26T15:14:04, about 23.4 hours after the trigger. A optical counterpart was still observable.
The preliminary analysis results are shown as follows:
+----------------+------------+----------+--------------+----------------+
| Tmid-T0 [hr] | Exp. [s] | Filter | Mag | 5-sigma U.L. |
+================+============+==========+==============+================+
| 23.4 | 1800 | sdssr |21.34 +/-0.09 | 22.3 |
+----------------+------------+----------+--------------+----------------+
We acknowledge the staff at the Lijiang Observatory for their efforts in conducting the observation.
GCN Circular 37307
Subject
GRB 240825A: NUTTelA-TAO / BSTI Optical Limits
Date
2024-08-27T04:22:06Z (a year ago)
From
Zhanat Maksut at Nazarbayev University <zhanat.maksut@nu.edu.kz>
Via
Web form
Z. Maksut (NU), B. Grossan (UCB, NU), T. Komesh (NU), Z. Abdullayev (NU), M. Krugov (FAI) and E. Abdikamalov (NU) report on behalf of the Energetic Cosmos Laboratory:
The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) observed the field of GRB 240825A, 3.7 h after receipt an automated GCN / BAT position alert, observing in Sloan g' and r' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).
We started observations of GRB 240825A (Gupta et al., GCN 37274; Jiang et al. GCN 37275; Dutton et al. GCN 37276; Odeh et al. GCN 37277; Zhang et al. GCN 37278; Li et al. GCN 37280; Izzo & Malesani, GCN 37287; Lipunov et al. GCN 37289; Leonini et al. GCN 37291; Wu et al. GCN 37292; Martin-Carrillo et al. GCN 37293) at UT 19:34:01 on 2024-08-25, 3.7 h after the BAT trigger. Observations were made in partly cloudy conditions. We report the following upper limit results:
start time t-t0(h) end time UL g' UL r' exposure_time (s)
-----------------------------------------------------------------------
19:34:01 3.7 19:43:01 19.31 19.38 10x60
start time is in UT. t-t0(h) gives the time since the trigger, in hours. UL gives the 5 sigma upper limit sensitivity in magnitudes, for images co-added to the given exposure time. Calibration was done with 4 Pan-STARRS catalog stars on our images.
----------------------------------
NU = Nazarbayev University, Nur-Sultan, Kazakhstan
UCB = University of California, Berkeley, USA
FAI = Fesenkov Astrophysical Institute, Kazakhstan
This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP14870504). The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazakhstan.
GCN Circular 37310
Subject
GRB 240825A: TNG optical photometry and spectroscopy
Date
2024-08-27T10:19:29Z (a year ago)
From
Andrea Melandri at INAF-OAR <andrea.melandri@inaf.it>
Via
Web form
A. Melandri (INAF-OAR), P. D'Avanzo, M. Ferro (INAF-OAB), V. D'Elia (INAF/OAR & ASI/ASDC), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Rossi (INAF-OAS), A. Harutyunyan , and D. Carosati (INAF-TNG) report on behalf of the CIBO collaboration:
We observed the optical afterglow of long bright GRB 240825A (Gupta et al., GCN 37274; Fermi GBM team, GCN 37273; Di Lalla et al., GCN 37288; Frederiks et al., GCN 37302) with the 3.6m Telescopio Nazionale Galileo (TNG) equipped with the DOLoRes camera in spectroscopic mode. Observations were carried out with the LR-B grism, covering the range 3500-8000 AA. The observations consisted of one spectrum carried out at a mean time of Aug 25.9562 UT (~7.4 hours after the burst).
In the acquisition image we clearly detect the optical afterglow (Gupta et al., GCN 37274; Jiang et al. GCN 37275; Dutton et al. GCN 37276; Odeh et al. GCN 37277; Zhang et al. GCN 37278; Li et al. GCN 37280; Izzo & Malesani, GCN 37287; Lipunov et al. GCN 37289; Leonini et al. GCN 37291; Wu et al. GCN 37292; Brivio et al. GCN 32795; Odeh, GCN 37299) with a magnitude r~20, calibrated against the Pan-STARRS catalogue.
The spectrum has a low SNR. From a preliminary reduction, we identify a single absorption feature consistent with Mg II at a redshift of z~0.66, in agreement with the results reported by Martin-Carrillo et al. (GCN 37293).
GCN Circular 37313
Subject
GRB 240825A: SAO RAS optical observations
Date
2024-08-28T00:51:15Z (a year ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS)
report on behalf of the GRB follow-up team.
We observed the field of the GRB 240825A (The Fermi GBM team,
GCN 37273; Gupta et al., GCN 37274; Lalla et al., GCN 37288;
Evans et al., 37290; Gropp et al., GCN 37294; Joshi et al.,
GCN 37298; Sharma et al., GCN 37301; Frederiks et al., GCN 37302)
with the SAO RAS 1-meter telescope Zeiss-1000 equipped with the
CCD-photometer on August 25/26, 26/27 and 27/28.
The weather conditions and seeing during the first and the second
nights were poor. The third night was good.
We obtained series of exposures in Rc band on
2024-08-25T20:37:53 -- 2024-08-25T22:32:59;
2024-08-26T22:33:48 -- 2024-08-27T01:29:03;
2024-08-27T19:51:04 -- 2024-08-27T21:15:46.
The OT (Gupta et al., GCN 37274; Jiang et al., GCN 37275;
Dutton et al., GCN 37276; Odeh and Guessoum, GCNs 37277, 37299;
Zhang et al., GCN 37278; Li et al., GCN 37280; Izzo and Malesani,
GCN 37287; Lipunov et al., GCN 37289; Leonini et al., GCN 37291;
Wu et al., GCN 37292; Martin-Carrillo et al., GCN 37293;
Brivio et al., GCN 37295; Kuin et al., GCN 37296; Le Floc’h et al.,
GCN 37300; Zheng and Filippenko, GCN 37304; Wang et al., GCN 37306;
Maksut et al., GCN 37307; Melandri et al., GCN 37310) is clearly
detected in the stacked frame only during the third night.
The non-detection of OT during our first and second nights is
consistent with the magnitudes reported by the other teams.
Our results are following.
Date T_mid - T0, d exp, s magnitude
Aug 25 0.2378 1080 R_lim = 19.5
Aug 26/27 1.3392 1483 R_lim = 21.0
Aug 27 2.1948 4200 R = 21.88 +/- 0.07
Our stacked frames are calibrated against nearby Pan-STARRS objects
and not corrected for the MW extinction.
GCN Circular 37314
Subject
GRB 240825A: ALMA detection
Date
2024-08-28T01:28:11Z (a year ago)
From
Tanmoy Laskar at U of Utah <tanmoylaskar@gmail.com>
Via
legacy email
T. Laskar (University of Utah), K. D. Alexander (University of Arizona), C.
Christy (University of Arizona), C. Peña (University of Utah), G. Schroeder
(Northwestern University), 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 240825A (Gupta et al., GCN 37274) with the Atacama Large
Millimeter/Submillimeter Array (ALMA) at 97.5 GHz beginning on 2024 August
27 03:22 UT (35.5 h after the burst). ALMA observations of this burst were
delayed due to uninterruptible scheduled Cycle 11 software validation at
the Observatory.
Preliminary analysis reveals a mm source with flux density of ~ 0.3 mJy at
position:
RA (J2000) = 22:58:17.27
Dec (J2000) = +01:01:36.73
with uncertainty ~ 0.07" in each coordinate, consistent with the X-ray
position (Evans et al., GCN 37290) and optical position (Gupta et al., GCN
37274; Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN
37277; Li et al., GCN 37280; Leonini et al., GCN 37291; Kuin et al., GCN
37296). Further observations are planned.
We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help
with these observations."
GCN Circular 37315
Subject
GRB 240825A: GECAM detection
Date
2024-08-28T09:07:31Z (a year ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
Chen-Wei Wang (IHEP), Shao-Lin Xiong (IHEP) report on behalf of the GECAM team:
GECAM-B was triggered in-flight by a long burst, GRB 240825A at 2024-08-25T15:53:00 UTC (denoted as T0), which was also detected by many missions, including Swift (R. Gupta et al., GCN 37274), Fermi/LAT (N. Di Lalla et al., GCN 37288), AstroSat (J. Joshi et al., GCN 37298), Fermi/GBM (V. Sharma et al., GCN 37301) and Konus-Wind (D. Frederiks et al., GCN 37302).
According to the event-by-event data of GECAM-B, this burst mainly consists of a short bright pulse followed by many overlapping short pulses with a T90 of 5.6 s +/- 0.3 s from 40 keV to 6000 keV.
The time-averaged spectrum from T0 to T0+10 s could be adequately fit by Band function with Epeak = 264 +/- 19 keV, alpha = -0.79 +/- 0.08, and beta = -2.10 +/- 0.05. The fluence of this time interval is (1.43 +/- 0.07) E-4 erg/cm2 in 40-8000 keV. With the redshift reported by VLT/X-shooter (A. Martin-Carrillo et al., GCN 37293), the isotropic energy release Eiso is about 1.7E53 erg.
The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecamgrb240825A.png
During GRB 240825A, GECAM-C was in the high latitude region where only two gamma-ray detectors (i.e. GRD01 and GRD07) are set to collect data normally, and both of them clearly detected this bright burst.
We note that these results are preliminary. Refined analysis will be reported later.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular 37322
Subject
GRB 240825A: VLA detection
Date
2024-08-28T16:53:27Z (a year ago)
From
corinna.pena@utah.edu
Via
Web form
C. Peña (University of Utah), T. Laskar (University of Utah), G. Schroeder (Northwestern University), K. D. Alexander (University of Arizona), C. Christy (University of Arizona), 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 240825A (Gupta et al., GCN 37274) with the Very Large Array (VLA) at multiple frequencies beginning on 2024 August 27 at 07:10 UT (39.3 hours post burst).
In preliminary analysis, we detect the radio counterpart (Laskar et al., GCN 37314) at 8.6 GHz with a flux density of F ~ 0.3mJy at the position:
RA(J2000) = 22:58:17.27 +/- 0.01”
Dec(J2000) = +01:01:36.78 +/- 0.02”
This is consistent with the X-ray position (Evans et al., GCN 37290), optical position (Gupta et al., GCN 37274; Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN 37277; Li et al., GCN 37280; Evans et al., GCN 37290; Leonini et al., GCN 37291; Kuin et al., GCN 37296), and radio position (Laskar et al., GCN 37314). Further observations are planned.
We thank the VLA staff for scheduling and executing these observations.”
GCN Circular 37326
Subject
GRB 240825A: Upper limits from a neutrino search with IceCube
Date
2024-08-28T20:37:55Z (a year ago)
From
Jessie Thwaites at IceCube/U Wisc-Madison <thwaites@wisc.edu>
Via
Web form
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
IceCube has performed a search for track-like muon neutrino events arriving from the direction of GRB 240825A (GCN Circular 37274 (Swift); 37301 (Fermi-GBM)). The search was performed at the position of the candidate optical counterpart reported by Swift-UVOT in a time range of -1 hour/+2 hours from the initial trigger reported by Swift-BAT (T0=2024-08-25 15:52:59 UTC) during which IceCube was collecting good quality data.
Zero track-like events are found to be coincident with the position of the GRB. We accordingly derive a time-integrated muon-neutrino flux upper limit for this source of E^2 dN/ dE = 2.8 x 10^-2 GeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum have energies in the approximate energy range between 1 TeV and 5 PeV.
A subsequent search was performed including 2 days of data centered on the Swift-BAT trigger (2024-08-24 15:52:59 UTC to 2024-08-26 15:52:59 UTC). In this case, we report a p-value of 1.0, consistent with background expectation. We accordingly derive a time-integrated muon-neutrino flux upper limit for this source of E^2 dN/ dE = 3.0 x 10^-2 GeV cm^-2 at 90% CL, under the assumption of an E^-2 power law.
The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu.
[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
GCN Circular 37335
Subject
GRB 240825A: iTelescope optical observations
Date
2024-08-29T04:47:21Z (a year ago)
From
Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com>
Via
legacy email
I observed the field of GRB 240825A (Gupta et al., GCN Circ. 37274)
remotely using telescope T73 (0.356-m f/7.2 Corrected Dall-Kirkham +
CMOS) of iTelescope.Net (located in Deep Sky Chile at Rio Hurtado
Valley, Chile) on 2024-08-26. Five images (exposure times of 300
seconds, BINx1) were obtained with Luminance filter with mid time
03:22:03 UT (11.48 h. after the trigger). I clearly detected the
optical afterglow in the UVOT position. I measured the magnitude of it
= 21.0 +/- 0.2 compared to r magnitudes of nearby stars from
Pan-STARRS DR1 catalogue (Chambers et al., 2016).
Magnitude was not corrected for Galactic extinction.
Stacked image: https://www.flickr.com/photos/filipp-romanov/53955441999
F. D. Romanov (AAVSO).
GCN Circular 37336
Subject
GRB 240825A: further SAO RAS optical observations
Date
2024-08-29T09:58:26Z (a year ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS)
report on behalf of the GRB follow-up team.
We observed the field of the GRB 240825A (The Fermi GBM team,
GCN 37273; Gupta et al., GCN 37274; Lalla et al., GCN 37288;
Evans et al., 37290; Gropp et al., GCN 37294; Joshi et al.,
GCN 37298; Sharma et al., GCN 37301; Frederiks et al., GCN 37302;
Wang and Xiong, GCN 37315) with the SAO RAS 1-meter telescope
Zeiss-1000 equipped with the CCD-photometer and UBVRcIc filters.
We obtained 18 x 300 sec. images with Rc filter on August 28,
19:17:07 -- 21:04:35 UT (t_mid - T0 = 3.1791 days).
The OT (Gupta et al., GCN 37274; Jiang et al., GCN 37275;
Dutton et al., GCN 37276; Odeh and Guessoum, GCNs 37277, 37299;
Zhang et al., GCN 37278; Li et al., GCN 37280; Izzo and Malesani,
GCN 37287; Lipunov et al., GCN 37289; Leonini et al., GCN 37291;
Wu et al., GCN 37292; Martin-Carrillo et al., GCN 37293;
Brivio et al., GCN 37295; Kuin et al., GCN 37296; Le Floc’h et al.,
GCN 37300; Zheng and Filippenko, GCN 37304; Wang et al., GCN 37306;
Maksut et al., GCN 37307; Melandri et al., GCN 37310;
Romanov, GCN 37335) is clearly detected in the stacked frame
with the brightness of R = 22.15 +/- 0.07 calibrated against
nearby Pan-STARRS stars (magnitudes converted to R band)
and not corrected for the MW extinction.
GCN Circular 37338
Subject
GRB 240825A: SVOM/VT optical detection
Date
2024-08-29T14:56:40Z (a year ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
SVOM/VT commissioning team: Y. L.Qiu, L. P. Xin, H. L. Li, C. Wu, X. H. Han, H. B. Cai, Y. Xu, Y. J. Xiao, P. P. Zhang, L. Lan, W. J. Xie, X. M. Lu, R. S. Zhang, D. W. Xu, G. W. Li (NAOC), J. Zhang, L. J. Dan, G. Y. Zou, C. J. Wang, Y. F. Du, C. Huang (XIOPM) and P.Jesse (CEA).
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 of SVOM mission, we observed the field of the GRB 240825A (The Fermi GBM team,GCN 37273; Gupta et al., GCN 37274; Lalla et al., GCN 37288; Evans et al., 37290; Gropp et al., GCN 37294; Joshi et al., GCN 37298; Sharma et al., GCN 37301; Frederiks et al., GCN 37302; Wang and Xiong, GCN 37315) with SVOM/VT telescope started at 2024-08-26T18:16:41.50 UT (about 26.4 hours after the burst) in ToO mode. VT made the observations with two channels simultaneously, VT_B (400nm-650nm) and VT_R (650nm-1000nm). The optical afterglow (Gupta et al., GCN 37274; Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN 37277, Zhang et al., GCN 37278; Li et al., GCN 37280, Izzo et al., GCN 37287; Lipunov et al., GCN 37289; Leonini et al., GCN 37291; Wu et al., GCN 37292; Martin-Carrillo et al., GCN 37293; Brivio et al., GCN 37295; Kuin et al., GCN 37296; Odeh et al., GCN 37299; Le Floc'h et al., GCN 37300; Guiffreda et al., GCN 37303, Zheng et al., GCN 37304, Wang et al., GCN 37306, Maksut et al., GCN 37307; Melandri et al., GCN 37310, Romanov, GCN 37335, Moskvitin et al., GCN37336) was detected in the VT stacked images, the magnitudes obtained by VT were: VT_B = 22.39 +/-0.2 mag, and VT_R = 21.12 +/-0.1 mag in AB magnitude.
More detailed analysis is ongoing.
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. VT is an optical telescope on board SVOM with an aperture of 44 cm, designed to automatically follow the Eclairs triggers. It has two channels: VT_B and VT_R, covering wavelengths from 400 nm to 650 nm and 650 nm to 1000 nm, respectively. The two bands are observed simultaneously. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS.
GCN Circular 37353
Subject
GRB 240825A: MeerKAT detection
Date
2024-08-30T21:26:36Z (a year ago)
From
Genevieve Schroeder at Northwestern University <genevieveschroeder@u.northwestern.edu>
Via
Web form
C. Peña (University of Utah), G. Schroeder (Northwestern University), T. Laskar (University of Utah), K. D. Alexander (University of Arizona), C. Christy (University of Arizona), E. Berger (Harvard University), R. Chornock (UC Berkeley), W. Fong (Northwestern University), R. Margutti (UC Berkeley), P. Schady (University of Bath), S. de Wet (University of Cape Town) and
P. Groot (Radboud University) report on behalf of a larger collaboration:
“We observed GRB 240825A (Gupta et al., GCN 37274) with the MeerKAT radio telescope at 1.3 GHz and 3 GHz beginning on 2024 August 29 at 20:34 UT (100.7 hours post burst).
In preliminary analysis, we detect the radio counterpart (Laskar et al., GCN 37314) at 1.3 GHz with a flux density of F ~ 0.16 mJy at the position:
RA (J2000) = 22:58:17.32
Dec (J2000) = +01:01:35.74
with uncertainty ~1.3" in each coordinate, consistent with the X-ray position (Evans et al., GCN 37290), optical position (Gupta et al., GCN 37274; Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN 37277; Li et al., GCN 37280; Evans et al., GCN 37290; Leonini et al., GCN 37291; Kuin et al., GCN 37296), and radio position (Laskar et al., GCN 37314, Peña et al., GCN 37322). Further observations are planned.
We thank the MeerKAT staff for scheduling and executing these observations. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation.”
GCN Circular 37355
Subject
GRB 240825A: Swift-BAT refined analysis
Date
2024-08-30T23:32:53Z (a year ago)
From
Amy <yarleen@gmail.com>
Via
email
M. J. Moss (GSFC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm
(NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (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+800 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 240825A (trigger #1250617)
(Gupta et al., GCN Circ. 37274). The BAT ground-calculated position is
RA, Dec = 344.570, 1.019 deg which is
RA(J2000) = 22h 58m 16.9s
Dec(J2000) = +01d 01' 08.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 53%.
The mask-weighted light curve shows a very bright FRED-like pulse that
starts at ~T0 and peaks at ~T+1.8 s. In addition, there are some secondary
pulses on top of the main FRED-like structure. The main structure ends at
~T+10 s, and there is a long tail emission that lasts till ~T+300 s. T90
(15-350 keV) is 57.20 +- 8.57 sec (estimated error including systematics).
The time-averaged spectrum from T-0.04 to T+216.76 sec is best fit by a
simple power-law model. The power law index of the time-averaged spectrum
is 1.20 +- 0.03. The fluence in the 15-150 keV band is 2.5 +- 0.04 x
10^-05 erg/cm2. The 1-sec peak photon flux measured from T+1.44 sec in the
15-150 keV band is 100.0 +- 1.7 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/1250617
GCN Circular 37361
Subject
GRB 240825A: SOAR observations
Date
2024-08-31T13:26:09Z (a year ago)
From
James Freeburn at Swinburne University of Technology <jamesfreeburn54@gmail.com>
Via
Web form
J. Freeburn (Swinburne/OzGrav) and I. Andreoni (UNC/UMD/NASA)
We observed the field of GRB 240825A (The Fermi GBM team,
GCN 37273; Gupta et al., GCN 37274; Lalla et al., GCN 37288;
Evans et al., 37290; Gropp et al., GCN 37294; Joshi et al.,
GCN 37298; Sharma et al., GCN 37301; Frederiks et al., GCN 37302;
Wang and Xiong, GCN 37315; Moss et al., GCN 37355) with the
Goodman High Throughput Spectrograph mounted on the SOAR telescope
in imaging mode. We took one 300s exposure each in filters
g,r and i between 2024-08-31T04:45:51 and 2024-08-31T05:00:23 UTC.
We place upper limits on the optical counterpart to GRB 240825A
(Gupta et al., GCN 37274; Jiang et al., GCN 37275; Dutton et al.,
GCN 37276; Odeh et al., GCN 37277; Zhang et al., GCN 37278;
Li et al., GCN 37280; Izzo et al., GCN 37287; Lipunov et al.,
GCN 37289; Leonini et al., GCN 37291; Wu et al., GCN 37292;
Martin-Carrillo et al., GCN 37293; Brivio et al., GCN 37295;
Kuin et al., GCN 37296; Odeh et al., GCN 37299; Le Floc'h et al.,
GCN 37300; Guiffreda et al., GCN 37303; Zheng et al., GCN 37304;
Wang et al., GCN 37306; Maksut et al., GCN 37307; Melandri et al.,
GCN 37310; Romanov, GCN 37335; Moskvitin et al., GCN 37336;
Qiu et al., GCN 37338). Zeropoints for each filter were measured
using the Pan-STARRS1 catalogue. Our AB magnitude 5-sigma upper
limits are as follows:
g > 23.2
r > 23.1
i > 22.8
GCN Circular 37367
Subject
GRB 240825A: TSHAO Optical Upper Limit
Date
2024-09-01T10:49:55Z (a year ago)
From
Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>
Via
legacy email
S. Belkin (HSE, IKI), I. Reva (FAI), A. Pozanenko (IKI), N. Pankov (HSE,
IKI) report on behalf of the IKI GRB FuN:
We observed the field of Fermi GRB 240825A (Fermi GBM Team, GCN 37273;
Gupta et al., GCN 37274; Di Lalla et al., GCN 37288; Kuin et al., GCN
37296; Joshi et al., GCN 37298; Sharma and Meegan, GCN 37301; Frederiks et
al., GCN 37302; Laskar et al., GCN 37314) using the Zeiss-1000 telescope at
Tien Shan Astronomical Observatory, starting on 2024-08-26 at 15:04:36 UT
in the R filter. We did not detect the optical afterglow (Gupta et al., GCN
37274; Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh and
Guessoum, GCN 37277; Zhang et al., GCN 37278; Li et al., GCN 37280; Izzo et
al., GCN 37287; Lipunov et al., GCN 37289; Leonini et al., GCN 37291;
SVOM/C-GFT Team, GCN 37292; Martin-Carrillo et al., GCN 37293; Brivio et
al., GCN 37295; Kuin et al., GCN 37296; Odeh and Guessoum, GCN 37299; Le
Floc’h et al., GCN 37300; Guiffreda et al., GCN 37303; Zheng and
Filippenko, GCN 37304; Wang et al., GCN 37306; Maksut et al., GCN 37307;
Melandri et al., GCN 37310; Moskvitin et al., GCN 37313, 37336 ; Romanov
GCN 37336; Qiu et al., GCN 37338; Freeburn et al., GCN 37361; ) at a
redshift of z = 0.659 (Martin-Carrillo et al., GCN 37293; Melandri et al.,
GCN 37310).
Preliminary photometry is as follows:
Date UT Start t-T0 (mid, days) Filter Exp. (s) OT Err. UL (3σ)
2024-08-26 15:04:36 0.98097 R 21x120 n/d n/d 21.3
The photometry was based on nearby USNO-B1.0 stars:
RA DEC R2
22:58:26.6335 +01:01:11.863 14.45
22:58:14.8740 +00:55:48.392 13.57
GCN Circular 37372
Subject
GRB 240825A: MeerLICHT afterglow detection
Date
2024-09-02T08:12:26Z (a year ago)
From
Simon de Wet at University of Cape Town <simdewet@gmail.com>
Via
Web form
S. de Wet (UCT), P.M. Vreeswijk (Radboud) and P.J. Groot (Radboud/UCT/SAAO) report on behalf of the MeerLICHT consortium:
The 0.6 m wide-field MeerLICHT optical telescope located in Sutherland, South Africa, obtained a repeated series of 60 s exposures in the q,u,g,r,i,z bands of GRB 240825A following the Swift detection (Gupta et al., GCN 37274). Observations started at 20:55:58 UT on 2024 August 25 (5.03 hours post-trigger) and continued for a further 5.87 hours, following the filter sequence quqgqrqiqz.
Since the afterglow was near our single-exposure detection limit due to poor seeing conditions, we coadded multiple exposures in each filter in order to obtain deeper images. We detect the optical afterglow at the UVOT position with the following AB magnitudes at a mean time of 01:03:03 UT on 2024 August 26:
g = 20.68 +/- 0.23
q = 20.81 +/- 0.20
i = 20.24 +/- 0.36
MeerLICHT is built and run by a consortium consisting of Radboud University, University of Cape Town, the South African Astronomical Observatory, the University of Oxford, the University of Manchester and the University of Amsterdam.
GCN Circular 37373
Subject
GRB 240825A: Magnitude Correction in SVOM/C-GFT Optical Observations
Date
2024-09-02T13:29:52Z (a year ago)
From
Chao Wu at NAOC <wuchao.lamost@gmail.com>
Via
Web form
SVOM/C-GFT team: Chao Wu (NAOC), Zhe Kang (CHO)，Liping Xin(NAOC),Xuhui Han(NAOC),Pinpin Zhang (NAOC)，Xiaomeng Lu (NAOC), Zhenwei Li (CHO)，You Lv (CHO)，Ruosong Zhang (NAOC)，Yujie Xiao(NAOC)
SVOM JSWG: Jian-Yan Wei (NAOC, China), Bertrand Cordier (CEA, F), Shuang-Nan Zhang (IHEP, CN), Stephane Basa (LAM, F), Jean-Luc Attéia (IRAP, F), Arnaud Claret (CEA, F), Zi-Gao Dai (USTC, CN), Frederic Daigne (IAP, F), Jin-Song Deng (NAOC, CN), Andrea Goldwurm (APC, F), Diego Götz (CEA, F), Xu-Hui Han (NAOC, CN), Cyril Lachaud (APC, F), En-Wei Liang (GXU, CN), Yu-Lei Qiu (NAOC, CN), Susanna Vergani (Obs.Paris, F), Jing Wang (NAOC, CN), Chao Wu(NAOC, CN), Li-Ping Xin (NAOC,CN), Bing Zhang (UNLV, CN)
After taking refined analysis on the Optical Observations (Wu et al. GCN 37292), we fixed a bug in the flux calibration pipeline. We update the afterglow magnitude of GRB 240825A as following,
-----------------------------------------------------------
Filter (t-T0) sec mag +/- mag_error
g 65 -> 2555 13.73 +/- 0.02 -> 18.58 +/- 0.28
r 206 -> 2088 15.11 +/- 0.02 -> 17.93 +/- 0.15
i 294 -> 2162 15.14 +/- 0.02 -> 17.68 +/- 0.15
The magnitudes were calibrated using nearby PS1 stars.
We apologize for any confusion caused.
GCN Circular 37388
Subject
GRB 240825A: ATCA Detection of Radio Counterpart
Date
2024-09-05T02:51:28Z (10 months ago)
From
agul8829@uni.sydney.edu.au
Via
Web form
A. Gulati (USyd), J. K. Leung (UofT/HUJI), G. E. Anderson (Curtin)
We observed GRB 240825A (Gupta et al., GCN 37274; Fermi GBM team, GCN 37273) with the the Australia Telescope Compact Array (ATCA) at multiple frequencies starting at 09:00 UTC on 1st September 2024.
In our preliminary analysis, we detect a radio counterpart at 5.5 GHz with a flux density of ~0.2 mJy at a position consistent with the X-ray position (Evans et al., GCN 37290), optical position (Gupta et al., GCN 37274; Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN 37277; Li et al., GCN 37280; Evans et al., GCN 37290; Leonini et al., GCN 37291; Kuin et al., GCN 37296), and radio position (Laskar et al., GCN 37314, Peña et al., GCN 37322,37353). Further observations are planned.
We thank the CSIRO Space and Astronomy staff for supporting these observations.
We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.
GCN Circular 37400
Subject
GRB 240825A: Montarrenti Observatory optical follow-up observations
Date
2024-09-05T20:40:42Z (10 months ago)
From
Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini@iol.it>
Via
Web form
S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy, part of UAI/SSV-GRB section), A. Lorini, G. Verna (University of Siena – DSFTA), G. Bonnoli (INAF – Brera Astronomical Observatory) report:
As a follow-up of our early observations of the GRB 240825A (Fermi/GBM team, GCN 37273; Gupta et al., GCN 37274; Di Lalla et al., GCN 37288; Evans et al., GCN 37290; Gropp et al., GCN 37294; Kuin et al., GCN 37296; Joshi et al., GCN 37298; Sharma et al., GCN 37301; Frederiks et al., GCN 37302; Chen-Wei et al., GCN 37315; Moss et al., GCN 37355) already reported in GCN 37291, we kept on imaging the afterglow until 2024-08-26 01:32:48 UT with the same set-up and data analysis procedure. Observations were performed under thin cloud cover in the second part of the night.
Here is our complete set of measurements:
Observation Mid-Time T-T0 (hr) Exposure Filter Mag. Err.
2024-08-25 21:12:38 UT 5.33 50x40s Rc 19.81 +/-0.10
2024-08-25 21:47:40 UT 5.92 60x40s Rc 19.97 +/-0.11
2024-08-25 22:33:13 UT 6.66 60x40s Rc 20.26 +/-0.12
2024-08-25 23:18:46 UT 7.43 58x40s Rc 20.49 +/-0.16
2024-08-26 00:04:19 UT 8.18 50x40s Rc 20.78 +/-0.22
2024-08-26 00:49:57 UT 8.95 60x40s Rc 20.71 +/-0.19
Along the span of our observations and within our uncertainties, the afterglow evolves in agreement with a power-law decay with a rate alpha=1.87+/-0.20
GCN Circular 37454
Subject
GRB 240825A: 7DT Optical Upper Limit
Date
2024-09-11T10:38:02Z (10 months ago)
From
Gregory Paek at Seoul National University <gregorypaek94@gmail.com>
Via
Web form
Gregory S.H. Paek (SNU ARC/SNU), Myungshin Im (SNU ARC/SNU), Hyeonho Choi (SNU ARC/SNU), Seo-Won Chang (SNU ARC/SNU), and Ji Hoon Kim (SNU ARC/SNU) report on behalf of the 7-Dimensional Telescope collaboration
We searched for the bright optical counterpart of the gamma-ray burst, GRB240825A (Fermi GBM team, GCN 37273; Gupta et al., GCN 37274) using the 7-Dimensional Telescopes (7DT). Approximately 10 hours following the initial detection (2024-08-25T15:53:00 UTC), we targeted the UVOT coordinate (Gupta et al., GCN 37274). Observations were made with nine 7DT units in medium-band filters, denoted as m400, m425, then through m825, in which the numeric values indicate their central wavelengths in nanometers. Each filter has a bandwidth of 25nm. In the preliminary result, no significant signal was found. Photometric flux calibration was performed using synthetic photometries derived from the Gaia DR3 XP catalog (Gaia Collaboration et al. 2022) within the AB magnitude system. The first unit of 7DT (m400 and m425 filters) temporarily experienced an electronic issue with the camera, resulting in relatively low sensitivity.
------
Filter Date-obs[UT] Exp.time[s] Depth(5sigma)
m400 2024-08-26T01:54:47 300 15.415
m425 2024-08-26T02:00:23 300 17.851
m450 2024-08-26T01:54:43 300 19.651
m475 2024-08-26T02:00:09 300 19.790
m500 2024-08-26T01:54:42 300 19.952
m525 2024-08-26T02:00:07 300 19.883
m550 2024-08-26T01:54:43 300 19.304
m575 2024-08-26T02:00:10 300 19.456
m600 2024-08-26T01:54:48 300 19.313
m625 2024-08-26T02:00:21 300 18.892
m650 2024-08-26T01:54:44 300 19.068
m675 2024-08-26T02:00:09 300 19.156
m700 2024-08-26T01:54:39 300 19.041
m725 2024-08-26T02:00:02 300 18.658
m750 2024-08-26T01:54:48 300 18.258
m775 2024-08-26T02:00:14 300 17.792
m850 2024-08-26T01:54:46 300 17.067
m875 2024-08-26T02:00:11 300 16.834
The 7-Dimensional Telescope (7DT), comprising 20 wide-field telescopes equipped with 40 medium-bandwidth (~25nm) filters located in Chile, aims to detect optical counterparts of GW sources and conduct the 7-Dimensional Sky Survey (7DS) of the Southern Hemisphere. Further information about the 7DT is available at http://gwuniverse.snu.ac.kr/.
GCN Circular 37536
Subject
GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
Date
2024-09-17T16:54:17Z (10 months ago)
From
Remo Ruffini at ICRA <ruffini@icra.it>
Via
Web form
R. Ruffini, C.L. Bianco, M. Della Valle, Liang Li, M.T. Mirtorabi, R. Moradi, F. Rastegar Nia, J.A. Rueda, Y. Wang, on behalf of the ICRANet team, report:
The T90 of GRB 240825A is only 4 seconds (GCN 37301), and it is located at a relatively close distance (z=0.659, GCN 37293). The fluence reaches a high level of 10^{-4} erg/cm^2. Through spectral analysis, we find that peak energy Ep is about 400 keV and isotropic energy Eiso is about 2x10^{53} erg, consistent with the Amati relation for long-duration gamma-ray bursts. Comparing its X-ray afterglow (see figure attached below, blue dots), its luminosity falls within the range of other long-duration bursts which are associated with supernovae, higher than those of short-duration bursts which have merge origins. Based on these findings, we conclude that GRB 240825A is a long-duration burst (BdHN I; see, e.g., Bianco, et al., 2024, ApJ, 966, 219) and is associated with a SN. The supernova may reach its optical peak in the observer's rest-frame approximately one month after the trigger. Its peak brightness should be within the detection limits of both ground- and space-based telescopes. Therefore, we encourage further observations in the coming weeks.
Figure: https://www.icranet.org/documents/GRB_240825A.png
GCN Circular 37537
Subject
GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
Date
2024-09-17T18:31:44Z (10 months ago)
From
Devraj Pawar at R. J. College, Mumbai - 86, India <devrajdp@gmail.com>
Via
Web form
Devraj Pawar (R. J. College, Mumbai-86, India) on behalf of a collaboration studying transients.
The Fermi GBM team reported the detection of a burst at 2024-08-25T15:53:00 UTC triggered by Fermi Gamma-ray Burst Monitor (GBM) in GCN 37273.
Follow up observations were reported in Gupta et al., GCN 37274; Di Lalla et al., GCN 37288; Evans et al., GCN 37290; Gropp et al., GCN 37294; Kuin et al., GCN 37296; Joshi et al., GCN 37298; Sharma et al., GCN 37301; Frederiks et al., GCN 37302; Chen-Wei et al., GCN 37315; Moss et al., GCN 37355; Leonini et al., GCN 37400; Paek al., GCN 37454; Ruffini et al., GCN 37536.
We analyzed the INTEGRAL SPI ACS data around the T0 given in GCN 37273 and detected a peak in the count rate which lasts for about 7 s. The SPI ACS is sensitive above 80 keV; the peak of the burst is at ~35000 counts/s and the steady rate preceding the event is around 3490 counts/s. The peak count rate may be affected by the instruments orientation with respect to the direction of the source. The light curve and the profile is given in the link below :
[GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE](https://docs.google.com/document/d/1de6UrFnIK8YoT4n61gwn11wn92oo9HlvxaronrH8RAk/edit?usp=sharing)
This work is based on observations with INTEGRAL, an ESA project with instruments and a science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), and with the participation of Russia and the USA. The SPI-ACS detector system has been provided by MPE Garching/Germany.
GCN Circular 37638
Subject
GRB 240825A: LBT optical observations
Date
2024-09-30T14:36:08Z (10 months ago)
From
Elisabetta Maiorano at INAF <elisabetta.maiorano@inaf.it>
Via
Web form
E. Maiorano, A. Rossi, E. Palazzi (INAF-OAS), D. Paris (OA Roma), D. B. Malesani (DAWN/NBI and Radboud Univ.), and M. De Pasquale (Univ. of Messina), report on behalf of the CIBO collaboration:
We observed the field of GRB 240825A (Fermi GBM team, GCN 37273; Gupta et al., GCN 37274) with the LBC camera mounted on LBT (Mt. Graham, AZ, USA) in r’ and z’ bands (45 min exposure time per filter) approximately at midtime 05:55:00 UT on 2024-09-12 (17.6 days after the burst).
The optical transient (Jiang et al. GCN 37275; Dutton et al. GCN 37276; Odeh et al. GCN 37277; Zhang et al. GCN 37278; Li et al. GCN 37280; Izzo & Malesani, GCN 37287; Lipunov et al. GCN 37289; Leonini et al. GCN 37291; Wu et al. GCN 37292; Brivio et al. GCN 32795; Odeh, GCN 37299) is well detected in r’ and z’ bands. Using PSF photometry, we measure a preliminary AB magnitude of
r'=22.8+-0.1,
calibrated against Pan-STARRS field stars, and not corrected for the foreground Galactic extinction.
We acknowledge the excellent support from the LBTO and LBTB staff, particularly Jan Snigula in obtaining these observations.