GRB 240805A

S. D. Barthelmy (GSFC), R. Gupta (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
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 240805A (trigger #1246907)
(Dichiara, et al., GCN Circ. 37032
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 ).  The BAT ground-calculated position is
RA, Dec = 190.919, -53.603 deg which is
   RA(J2000)  =  12h 43m 40.6s
   Dec(J2000) = -53d 36' 10.3"
with an uncertainty of 0.79 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 31%.

The mask-weighted BAT light curve shows a complex structure. T90 (15-350 keV) is 37.34 +- 6.22 sec (estimated error including systematics).

The time-averaged spectrum from T-3.936 to T+258.128 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.21 +- 0.06.  The fluence in the 15-150 keV band is 8.7 +- 0.3 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+3.28 sec in the 15-150 keV band
is 8.0 +- 0.5 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/1246907

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 240805A
(Fermi-GBM observation: The Fermi GBM team, GCN 27031
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 ; Godwin et al., GCN 37075
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 ;
Swift-BAT detection: Dichiara et al., GCN 37032
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 ;
INTEGRAL IBIS/ISGRI detection: Mereghetti et al., GCN 37037
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 ; Götz et al., GCN 37041
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 ;
Fermi-LAT detection: Gupta et al., GCN 37042
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 ;
SVOM/GRM observation: Wang et al., GCN 37054
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 )
triggered Konus-Wind at T0=7342.029 s UT (02:02:22.029).

The burst light curve shows a multipeaked structure
which starts at ~T0-2.3 s and has a total duration of ~15.6 s.
The emission is seen up to ~4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240805_T07342/

As observed by Konus-Wind, the burst
had a fluence of 3.43(-0.31,+0.35)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+3.680 s,
of 6.61(-1.44,+1.48)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+15.360 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 = -0.46(-0.11,+0.13),
the high energy photon index beta = -2.76(-0.43,+0.26),
the peak energy Ep = 272(-22,+22) keV
(chi2 = 81/80 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+7.168 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 = -0.51(-0.12,+0.14),
the high energy photon index beta = -2.78(-0.61,+0.29),
the peak energy Ep = 279(-26,+27) keV
(chi2 = 70/71 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.

M. Godwin (UAH), J. Smith (UAH), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:

At 02:02:20.31 UT on 05 August 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240805A (trigger 744516145/240805085),which was also detected by SVOM/GRM (SVOM/GRM team, 2024, GCN 37054
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 ), Fermi-LAT (R. Gupta et al. 2024, GCN 37042
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 ), INTEGRAL IBAS (S.Mereghetti et al. 2024, GCN 37037
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 ), and Swift-BAT (S. Dichiara et al. 2024, GCN 37032
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 ). The Final Real-time Localization (Fermi GBM Team 2024, GCN 37031
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 ) is consistent with the Fermi-LAT, Integral, and Swift positions.

The angle from the Fermi LAT boresight is 59 degrees.

The GBM light curve has many short peaks with a duration (T90) of about 10.8 s (50-300 keV). The time-averaged spectrum from T0-3.6 to T0+16.9 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.67 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 330 +/- 8 keV.

The event fluence (10-1000 keV) in this time interval is (2.91 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+5.8 s in the 10-1000 keV band is 14.3 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well with Epeak= 310 +/- 10 keV, alpha = -0.65 +/- 0.02 and beta = -2.9 +/- 0.3.

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/

M. H. Siegel (PSU) and S. Dichiara (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 240805A
105 s after the BAT trigger (Dichiara et al., GCN Circ. 37032
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 ).
No optical afterglow consistent with the XRT position
(Osborne, GCN Circ. 37045
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 ) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white              105         4086          269         >20.4
v                 4297         4497          197         >18.7
b                 3681         5128          205         >19.5
u                 3476         5113          393         >19.5
w1                4708         4908          197         >19.1
m2                4502         4701          197         >19.1
w2                4092         4292          197         >19.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.191 in the direction of the burst
(Schlegel et al. 1998).

SVOM/GRM team: Chen-Wei Wang, Yong-Wei Dong, Jiang-Tao Liu, Shi-Jie Zheng, Jian-Chao Sun, Wen-Jun Tan, Jiang He, Min Gao, Hao-Xuan Guo, Yue Huang, 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), Patrick Maeght (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 by a long GRB 240805A at 2024-08-05T02:02:21.400 UT (T0), which also triggered Fermi/GBM (GCN 37031
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 ), Swift/BAT (GCN 37032
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 ), INTEGRAL (GCN 37037
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 ), and Fermi/LAT (GCN 37042
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 ).

With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple pulses with a duration of about 12 s.

The GRM light curve can be found here:
https://www.bursthub.cn/admin/static/svgrb240805A.png

At the time of this burst ECLAIRs was not in operational mode.

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)

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) started inspect of the Fermi GRB 240805A ( Fermi GBM team, GCN 37031
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 ) errorbox  53052 sec after notice time and 53084 sec after trigger time at 2024-08-05 16:47:04 UT, with upper limit up to  18.5 mag. Observations started at twilight.  The observations began at zenith distance = 33 deg. The sun  altitude  is -9.3 deg. 

The galactic latitude b = 10 deg., longitude l = 303 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2551244

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   53174 | 2024-08-05 16:47:04 |         MASTER-SAAO | (12h 43m 20.61s , -53d 36m 01.3s) |   C |   180 | 16.1 |        
   53354 | 2024-08-05 16:47:04 |         MASTER-SAAO | (12h 43m 20.63s , -53d 36m 01.3s) |   C |   540 | 17.2 |  Coadd 
   53373 | 2024-08-05 16:50:23 |         MASTER-SAAO | (12h 43m 15.26s , -53d 36m 55.1s) |   C |   180 | 16.9 |        
   53573 | 2024-08-05 16:53:42 |         MASTER-SAAO | (12h 43m 23.40s , -53d 36m 25.3s) |   C |   180 | 17.4 |        
   53772 | 2024-08-05 16:57:02 |         MASTER-SAAO | (12h 43m 20.45s , -53d 34m 46.4s) |   C |   180 | 17.9 |        
   53971 | 2024-08-05 17:00:21 |         MASTER-SAAO | (12h 43m 21.17s , -53d 36m 24.1s) |   C |   180 | 18.2 |        
   54171 | 2024-08-05 17:03:41 |         MASTER-SAAO | (12h 43m 24.63s , -53d 34m 49.4s) |   C |   180 | 18.5 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

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 240805A ( S. Dichiara et al., GCN 37032
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 ) errorbox  53063 sec after notice time and 53081 sec after trigger time at 2024-08-05 16:47:04 UT, with upper limit up to  16.1 mag. Observations started at twilight.  The observations began at zenith distance = 33 deg. The sun  altitude  is -9.3 deg. 

The galactic latitude b =  9 deg., longitude l = 302 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2551196

We obtain a following upper limits.  

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

   53172 |         MASTER-SAAO |   C |   180 | 16.1 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), A.
Melandri (INAF-OAR), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto),
D.N. Burrows (PSU) and P.A. Evans report on behalf of the Swift-XRT
team:

We have analysed 1.7 ks of XRT data for GRB 240805A, from 89 s to 5.1
ks after the  BAT trigger. The data comprise 75 s in Windowed Timing
(WT) mode (the first 6 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. Using 1639 s of PC mode data
and 4 UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 190.91475, -53.59526 which is equivalent to:

RA (J2000): 12h 43m 39.54s
Dec(J2000): -53d 35' 42.9"

with an uncertainty of 2.1 arcsec (radius, 90% confidence).

The light curve can be modelled with an initial power-law decay with an
index of alpha=7.82 (+0.18, -2.12), followed by a break at T+97.3 s to
an alpha of 1.292 (+0.027, -0.026).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.79 (+/-0.08). The
best-fitting absorption column is  5.1 (+/-0.5) x 10^21 cm^-2, in
excess of the Galactic value of 2.3 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.52 (+0.23, -0.22)
and a best-fitting absorption column of 3.8 (+1.5, -1.2) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 5.3 x 10^-11 (6.6 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     3.8 (+1.5, -1.2) x 10^21 cm^-2
Galactic foreground: 2.3 x 10^21 cm^-2
Excess significance: 2.0 sigma
Photon index:	     1.52 (+0.23, -0.22)

If the light curve continues to decay with a power-law decay index of
1.292, the count rate at T+24 hours will be 0.020 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x
10^-12 (1.4 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/01246907.

This circular is an official product of the Swift-XRT team.

R. Gupta (NASA GSFC),  A. Holzmann (DF, University of Buenos Aires, Argentina), and F. Longo (University and INFN, Trieste) report on behalf of the Fermi-LAT Collaboration:

At 02:02:20.31 UT on August 05, 2024, Fermi-LAT detected high-energy emission from GRB 240805A which was also detected by Fermi-GBM (trigger 744516145 / 240805085, GCN 37031
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 ), Swift/BAT (GCN 37032
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 ), and INTEGRAL (GCN 37037
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 ).

The best LAT on-ground location is found to be

RA, Dec = 190.45, -54.02 (J2000)

with an error radius of 0.45 deg (90% containment, statistical error only).

This was 59 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance. The photon flux above 100 MeV in the time interval 0-100 s after the GBM trigger is (3.6 +/- 1.3) E-5 ph/cm2/s. The estimated photon index above 100 MeV is -2.0 +/- 0.3.

The highest-energy photon is a 1.6 GeV event which is observed about 17 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is Lorenzo Scotton (lorenzo.scotton AT uah.edu)

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.

D. Götz (CEA Irfu), S. Mereghetti (INAF, IASF Milano), C.Ferrigno, E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC, Versoix) and J.Borkowski (CAMK, Torun) report:

we performed futher analysis of GRB 240805A detected by GBM, Swift, and INTEGRAL (GCN 37031
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 , 37032
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 , 37037
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 ). Our spectral analysis provides a preliminary peak flux, integrated over 1 s, of 4.2 photons (4e-7 erg)/cmsq/s and a fluence of 2.4e-6 erg/cmsq in the 20-200 keV energy band. We note that both these values are lower limits due to telemetry limitations at satellite level.

S.Mereghetti (INAF, IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC, Versoix) and J.Borkowski (CAMK, Torun) report:

a gamma ray burst lasting about 40 s has been detected by IBAS in the  IBIS/ISGRI data at 02:02:20  UT of 2024 August 5.The burst was detected also by Fermi/GBM (GCN Circ. 37031
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 ) and Swift/BAT (GCN Circ. 37032
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 ).

The refined coordinates (J2000) are:
R.A.= 190.9054 deg
DEC.= -53.5962 deg
with an uncertainty of 1.5 arcmin (90% c.l.).

The burst light curve was affected by gaps due to telemetry saturation.

S. Dichiara (PSU), R. Gupta (NASA GSFC) and D. M. Palmer (LANL) report
on behalf of the Neil Gehrels Swift Observatory Team:

At 02:02:22 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 240805A (trigger=1246907).  Swift slewed immediately to
the burst but the observations was cut short almost immediately
after the end of slew due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 190.911, -53.622 which is 
   RA(J2000) = +12h 43m 39s
   Dec(J2000) = -53d 37' 17"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve is not immediately
available.  However, the original BAT trigger shows an excess
of 3.3k counts in 1.024 s (25-100 keV) at the time of the trigger. 

The XRT and UVOT observations were only a few seconds long, so
X-ray and optical positions and lightcurves will not be
available until the GRB comes out of constraint around 02:58 UT. 

Burst Advocate for this burst is S. Dichiara (sbd5667 AT psu.edu). 
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/)

The Fermi GBM team reports the detection of a likely LONG GRB

At 02:02:20 UT on 5 Aug 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240805A (trigger 744516145.309414 / 240805085).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 192.1, Dec = -52.9 (J2000 degrees, equivalent to J2000 12h 48m, -52d 53'), with a statistical uncertainty of 1.5 degrees.

The angle from the Fermi LAT boresight is 59.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240805085/quicklook/glg_skymap_all_bn240805085.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/bn240805085/quicklook/glg_healpix_all_bn240805085.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240805085/quicklook/glg_lc_medres34_bn240805085.gif