GRB 240805B
GCN Circular 37192
Subject
GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
Date
2024-08-16T19:36:14Z (a year ago)
From
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com>
Via
Web form
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
We imaged the field of the GRB 240805B detected at 14:28:54 UT by SWIFT (trigger num. 1246989) (M. A. Williams (PSU), S. Dichiara (PSU), R. Gupta (NASA GSFC),
J. A. Kennea (PSU) and D. M. Palmer (LANL) GCN 37043) with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy.
Member of:
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione
The observations started at 19:24 UT of 2024/08/05, after about 5 hours after the transient, with clear sky,
with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 45 image of 60 sec each. All images are unfiltered, calibrated with masterdark and masterflat,stacked with Tycho Tracker software
We have not detected any clearly visible sources, up to 19.5th magnitude with clear skies.
Start End Rlim
19:24:41 UT 20:27:39 UT 19.5
We did not found any optical counterpart.
Magnitudes were estimated with the Gaia DR2 cat. and
are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular 37086
Subject
GRB 240805B: GIT optical upper limit
Date
2024-08-06T22:49:44Z (a year ago)
From
vishwajeet.s@iitb.ac.in
Via
Web form
T. Mohan, R. Kumar, Y. Wagh, V. Swain, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the field of GRB240805B (Williams et al., GCN 37043) with the 0.7m GROWTH-India Telescope (GIT). The observations started at 2024-08-06 17:26:53 UT, 1.12 days after the Swift BAT trigger. We obtained 10 images of 240s exposure time in r' filter. We did not detect any new source in our stacked image around the coordinates reported by Swift-XRT detection (Goad et al., GCN 37053) and BTA 6-meter telescope (Moskvitin et al., GCN 37055). The obtained upper limit follows as:
--------------------------------------------------------------------------------------
| JD (mid) | t-t0 (days) | Filter | Exposure (s) | Limiting Magnitude (AB) |
| ------------------ | ----------- |------- | ------------ | ----------------------- |
| 2460529.2419108795 | 1.14 | r' | 10x240 | 22.5 |
--------------------------------------------------------------------------------------
Our result is consistent with the upper limits reported by (Strausbaugh et al, GCN 37052; Maksut et al, GCN 37060; Pankov et al., GCN 37072; Quadri et al., GCN 37076). The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT, Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular 37084
Subject
GRB 240805B: Swift-BAT refined analysis
Date
2024-08-06T20:26:19Z (a year ago)
From
Rahul Gupta at NASA GSFC <rahul.gupta@nasa.gov>
Via
email
H. A. Krimm (NSF), S. D. Barthelmy (GSFC),
R. Gupta (GSFC), 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-239 to T+1121 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 240805B (trigger #1246989)
(Williams, et al., GCN Circ. 37043). The BAT ground-calculated position is
RA, Dec = 254.215, 18.314 deg which is
RA(J2000) = 16h 56m 51.5s
Dec(J2000) = +18d 18' 49.9"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 85%.
The mask-weighted BAT light curve shows a complex structure with a duration of ~ 100 sec.
T90 (15-350 keV) is 64.99 +- 2.56 sec (estimated error including systematics).
The time-averaged spectrum from T-0.76 to T+96.68 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.07 +- 0.26, and Epeak of 72.1 +- 12.0 keV (chi squared 38.84 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.5 +- 0.2 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+15.95 sec in the 15-150 keV band is 2.4 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.71 +- 0.06 (chi squared 59.87 for 57 d.o.f.). 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/1246989
GCN Circular 37076
Subject
GRB 240805B Bassano Bresciano Observatory upper limit
Date
2024-08-06T15:20:26Z (a year ago)
From
Ulisse Quadri at Bassano Bresciano Observatory <osservatoriobassano@gmail.com>
Via
Web form
U.Quadri, L.Strabla and P.Madurini (Bassano Bresciano Astronomical Observatory),
Members of:
AAVSO - American Association of Variable Star Observers.
UAI - Unione Astrofili Italiani/GRB section.
GAC - Gruppo Astrofili Cremonesi.
In a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
We imaged the field of GRB 240805B detected by SWIFT (trigger num. 1246989)
with the robotic telescope of (IAU station 565) Bassano Bresciano Observatory, Italy.
The observations started 6.72 hour after the GRB trigger, At the end of twilight
with our Newton telescope D=450 mm F/D=4.5.
Weather conditions were good.
We co-added 2 series of 50 exposures of 20 sec each.
Start T0+ End T0+ Vlim
6.72 hour 7.02 hour 21.2
7.02 hour 7.35 hour 21.2
We did not found any optical counterpart in the error box of the XRTcandidate:
M. A. Williams et al., GCN 37043; Z.P. Zhu et al., GCN 37050; V. Lipunov et al., GCN 37051;
R. Strausbaugh et al., GCN 37052; A. Moskvitin et al., GCN 37055; Z. Maksut et al., GCN 37060;
Guowang Du et al., GCN 37062; N. Pankov et al., GCN 37072.
Magnitudes were estimated with the pan-STARRS cat.
and are derived using Lupton (2005) equations.
Not corrected for galactic dust extinction.
Reference:
http://www.osservatoriobassano.org/GRB.asp
The
GCN Circular 37074
Subject
GRB 240805B: JinShan optical afterglow detection
Date
2024-08-06T15:03:47Z (a year ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Via
Web form
Z.P. Zhu, X. Liu, J. An, S.Y. Fu, S.Q. Jiang, L.B. He, D. Xu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration:
We reported JinShan optical upper limits (GCN 37050) at the Swift/XRT position of GRB 240805B (Williams et al., GCN 37043).
Later on, the Enhanced Swift-XRT position was available (Goad et al., GCN 37053), which has a quite positional shift compared to the early position (Williams et al., GCN 37043).
Checking the Enhanced Swift-XRT position in the JinShan images, we find the optical afterglow (e.g., Moskvitin et al., GCN 37055; Du et al., GCN 37062) is detected in the r-/i-/z- bands. Thus, the updated preliminary results are as follows:
Telescope Tmid-T0/hr Filter Exptime Mag(AB) MagErr
50D 1.683 g 20x180s >21.5 -
100C 0.582 r 5x200s 20.03 0.06
100C 0.868 i 5x200s 18.79 0.02
100C 1.318 z 7x300s 18.79 0.02
We acknowledge the excellent support from S.W. Luo, M.M. Yang, Z.K. Feng, Q.C. Zhao and L.F. Huo for enabling these observations.
GCN Circular 37072
Subject
GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
Date
2024-08-06T14:20:22Z (a year ago)
From
Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>
Via
legacy email
N. Pankov (HSE, IKI), A. Pozanenko (IKI), V. Rumyantsev (CrAO), R. Ya.
Inasaridze (AbAO), A. Shikherin (KIAM) report on behalf of GRB-IKI-FuN:
We observed the field of GRB 240805B detected by Swift (Williams et al,
GCN 37043; Goad et al, GCN 37053) with AS-32 0.7-meter telescope of
Abastumani observatory (AbAO) in R-filter, ZTSh 2.6-meter telescope of CrAO
in R-filter, and K800 0.8-meter telescope of Terskol observatory in clear
filter. The observations began on 2024-08-05 at 17:30 UT at AbAO (i.e. 3.1
hr since Swift trigger) in variable conditions. We obtain
upper limits on the optical counterpart found and confirmed in (Moskvitin
et al, GCN 37055; Du et al, GCN 37062):
Date UT start t-T0 Exp. Filter OT Err. UL Observ./Scope
(mid, days) (s) (3-sigma)
2024-08-05 17:30:52 0.14442 52x60 R n/d n/d 20.2 AbAO/AS-32
2024-08-05 19:50:58 0.24449 30*120 R n/d n/d 20.5 CrAO/ZTSh
2024-08-05 20:10:07 0.23695 44*30 CR n/d n/d 17.0 Terskol/K800
The photometry was calibrated against nearby stars of USNO-B1.0 (R2
magnitudes). The upper limits are in agreement with no detections by (Zhu
et al, GCN 37050; Strausbaugh et al, GCN 37052; Siegel & Williams,
GCN 37057; Maksut et al, GCN 37060).
GCN Circular 37062
Subject
GRB 240805B: Optical detection with 1.6m Mephisto
Date
2024-08-06T08:26:44Z (a year ago)
From
Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn>
Via
Web form
Guowang Du (SWIFAR, YNU), Yuan Fang (SWIFAR, YNU), Yangwei Zhang (SWIFAR, YNU), Xuhui Han (NAOC), Pinpin Zhang (NAOC), Liping Xin (NAOC), Chao Wu (NAOC), Brajesh Kumar (SWIFAR, YNU), Baokun Sun (SWIFAR, YNU), Yuanpei Yang (SWIFAR, YNU), Xinzhong Er (SWIFAR, YNU), Xiangkun Liu (SWIFAR, YNU), Xiaowei Liu (SWIFAR, YNU)
We did simultaneous multi-band photometric observations of GRB 240805B (Williams et al., GCN 37043) using 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. The observations were started at (UTC) 2024-08-05 15:46:50 and multiple frames were obtained in uvgriz bands. In our preliminary analysis the OT candidate (Moskvitin et al., GCN 37055) is detected in r, i and z bands with the following magnitudes:
MJD Filter Mag (AB)
60527.65751 r 20.3+-0.2
60527.66333 i 18.2+-0.04
60527.65751 z 17.8+-0.08
60527.66333 u >21.1
60527.65751 v >21.2
60527.66333 g >20.9
-----------------------------------------------------------------------------------------------------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 37060
Subject
GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
Date
2024-08-06T06:07:28Z (a year ago)
Edited On
2024-08-06T15:13:50Z (a year ago)
From
Zhanat Maksut at Nazarbayev University <zhanat.maksut@nu.edu.kz>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Zhanat Maksut at Nazarbayev University <zhanat.maksut@nu.edu.kz>
Via
Web form
Z. Maksut (NU), B. Grossan (UCB, NU), T. Komesh (NU), Zh. 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 240805B, 1 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 at 15:29:10 UT on 2024-08-05, 1 h after the BAT trigger. Observations were made in clear conditions. No source consistent with the XRT (Goad et al., GCN 37053) was detected. We report the following results:
start time t-t0(h) end time UL g' UL r' exposure_time (s)
-----------------------------------------------------------------------
15:29:10 1 15:35:19 19.7 19.4 3x120
start time is in UT. t-t0(h) gives the time since 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 the 4 bright Pan-STARRS catalog stars on our images.
----------------------------------
NU = Nazarbayev University, Astana, Kazakhstan
UCB = University of California, Berkeley, USA
FAI = Fesenkov Astrophysical Institute, Almaty, 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 37059
Subject
GRB 240805B: Swift-XRT refined Analysis
Date
2024-08-06T02:27:11Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai
(INAF-IASFPA), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), A.
Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J. D. Gropp (PSU) and P.A.
Evans report on behalf of the Swift-XRT team:
We have analysed 8.2 ks of XRT data for GRB 240805B, from 71 s to 30.3
ks after the BAT trigger. The data comprise 4.5 ks in Windowed Timing
(WT) mode (the first 6 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode.
The late-time light curve (from T0+5.6 ks) can be modelled with a
power-law decay with a decay index of alpha=1.55 (+/-0.26).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.77 (+/-0.06). The
best-fitting absorption column is 1.19 (+0.21, -0.20) x 10^21 cm^-2,
in excess of the Galactic value of 7.6 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.9 (+0.4, -0.3) and
a best-fitting absorption column of 1.5 (+1.4, -0.7) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.6 x 10^-11 (4.6 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.5 (+1.4, -0.7) x 10^21 cm^-2
Galactic foreground: 7.6 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.9 (+0.4, -0.3)
If the light curve continues to decay with a power-law decay index of
1.55, the count rate at T+24 hours will be 3.4 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-13 (1.6 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01246989.
This circular is an official product of the Swift-XRT team.
GCN Circular 37057
Subject
GRB 240805B: Swift/UVOT Upper Limits
Date
2024-08-06T01:35:51Z (a year ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
Via
Web form
M. H. Siegel (PSU) and M. Williams (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 240805B
88 s after the BAT trigger (Williams et al., GCN Circ. 37043).
No optical afterglow consistent with the XRT position
(Goad et al., GCN Circ. 37053) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 88 238 147 >20.9
u_FC 301 551 246 >19.9
white 88 1719 411 >21.6
v 630 1768 136 >19.4
b 556 1694 117 >19.7
u 301 1669 343 >20.2
w1 679 1818 136 >19.6
m2 1256 1620 39 >19.2
w2 606 1744 136 >20.1
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.087 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 37055
Subject
GRB 240805B: BTA optical afterglow candidate
Date
2024-08-06T00:45:23Z (a year ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. Moskvitin, D. Oparin, A Vinokurov (SAO RAS), N. Pankov (HSE, IKI)
and A. Pozanenko (IKI) report:
We observed the field of the GRB 240805B (Williams et al., GCN 37043)
with the BTA 6-meter telescope of SAO RAS equipped with the focal
reducer Scorpio-I. We obtained 7 x 120 + 30 sec images on August 5,
2024-08-05T19:31:44 -- 2024-08-05T20:10:44 (t_mid - T0 = 8.372 hours).
Within the enhanced XRT error circle (Goad et al., GCN 37053) close
to its edge we detected a single source with the coordinates (J2000):
R. A. = 16:56:51.20
Dec. = +18:19:11.7 +/- 0".5
and brightness of R = 21.62 +/- 0.04 (calibrated against nearby SDSS
stars, magnitudes converted with Lupton 2005 equations)
and not corrected for Galactic extinction.
This source is located near SDSS object J165651.21+181914.0
but significantly brighter, thus it may be GRB OT.
GCN Circular 37053
Subject
GRB 240805B: Enhanced Swift-XRT position
Date
2024-08-05T23:15:38Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1007 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 240805B, 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 = 254.21255, +18.31958 which is equivalent
to:
RA (J2000): 16h 56m 51.01s
Dec (J2000): +18d 19' 10.5"
with an uncertainty of 3.1 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 37052
Subject
GRB 240805B: LCOGT Optical Upper Limits
Date
2024-08-05T19:37:57Z (a year ago)
From
Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>
Via
email
R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:
We observed the Swift GRB 240805B field (Williams et al., GCN 37043) with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on August 5, from 18:01 to 18:34 UT (corresponding to 3.55 to 4.10 hours after the GRB trigger time) with the sdss r and i filters.
We performed a series of 3x300s exposures in each band. We do not detect an uncataloged source within the XRT error region in either band. This result is consistent with other optcal upper limits (Zhu et al., GCN 37050; Lipunov et al., GCN 37051).
The following 5-sigma upper limits are calculated using the PanSTARRS catalog as reference:
r > 21.1
i > 20.5
These magnitudes are not corrected for galactic extinction.
GCN Circular 37051
Subject
Swift GRB 240805B: Global MASTER-Net observations report
Date
2024-08-05T19:18:29Z (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 240805B ( M. A. Williams et al., GCN 37043) errorbox 16180 sec after notice time and 16840 sec after trigger time at 2024-08-05 19:09:34 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 32 deg. The sun altitude is -19.2 deg.
The galactic latitude b = 33 deg., longitude l = 38 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2551783
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
16931 | MASTER-Tavrida | C | 180 | 16.5 |
16931 | MASTER-Tavrida | C | 180 | 17.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 37050
Subject
GRB 240805B: JinShan optical upper limits
Date
2024-08-05T17:34:05Z (a year ago)
From
Zipei Zhu at NAOC <zpzhu@nao.cas.cn>
Via
legacy email
Z.P. Zhu, X. Liu, J. An, S.Y. Fu, S.Q. Jiang, L.B. He, D. Xu (NAOC) report on behalf of a large collaboration:
We observed the field of GRB 240805B detected by Swift/BAT (Williams et al., GCN 37043), using the JinShan 100cm-C telescope (100C) and 50cm-D telescope (50D) located at Altay, Xinjiang, China.The observation started at 14:55:19 UT on 2024-08-05, ~ 0.44 hr after the BAT trigger. A series of exposures were obtained in the Sloan g-, r-, i-, and z- filters.
No uncataloged source is found within or around the XRT error circle (Williams et al., GCN 37043). The obtained upper limits are as follows:
Telescope Tmid-T0/hr Filter Exptime Mag(AB)
100C 0.582 r 5x200s >22.0
100C 0.868 i 5x200s >22.2
100C 1.318 z 7x300s >21.5
50D 1.683 g 20x180s >22.0
We acknowledge the excellent support from S.W. Luo, M.M. Yang, Z.K. Feng, Q.C. Zhao and L.F. Huo for enabling these observations.
GCN Circular 37043
Subject
GRB 240805B: Swift detection of a burst
Date
2024-08-05T14:51:03Z (a year ago)
From
David Palmer at LANL <palmer@lanl.gov>
Via
email
M. A. Williams (PSU), S. Dichiara (PSU), R. Gupta (NASA GSFC),
J. A. Kennea (PSU) and D. M. Palmer (LANL) report on behalf of the
Neil Gehrels Swift Observatory Team:
At 14:28:54 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 240805B (trigger=1246989). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 254.239, +18.323 which is
RA(J2000) = 16h 56m 57s
Dec(J2000) = +18d 19' 24"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 70 sec. The peak count rate
was ~2800 counts/sec (15-350 keV), at ~16 sec after the trigger.
The XRT began observing the field at 14:30:12.5 UT, 78.4 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 254.2153, 18.3175 which is equivalent to:
RA(J2000) = 16h 56m 51.67s
Dec(J2000) = +18d 19' 03.0"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 83 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 87 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.087.
Burst Advocate for this burst is M. A. Williams (mjw6837 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/)