GRB 241030B
GCN Circular 38158
R. Jayaraman (MIT), M.M. Fausnaugh (TTU), and G.R. Ricker (MIT) report:
The Transiting Exoplanet Survey Satellite (TESS; Ricker et al. JATIS 1 2015) observed GRB 241030B (Klingler et al., GCN 37981; Fermi GBM Team, GCN 37980) during its scheduled sky survey. TESS observed this region continuously from 3.72 days before the trigger to 2.71 days after the trigger, at a cadence of 200 seconds. The GRB occurred during TESS observational Sector 85, and the localization fell within Camera 1, CCD 4.
We performed forced difference-imaging photometry at the location of the confirmed X-ray afterglow (Evans et al., GCN 37992) using the full-frame images from the publicly available TICA data archived at MAST (https://archive.stsci.edu/hlsp/tica). Our data reduction routine is described in Fausnaugh et al. 2023 (ApJ 956(2):108).
We detect an optical transient at the location of the GRB in the 3 exposures during and after the time of trigger from Klingler et al. The trigger occurred 115 seconds before the end of a concurrent 200-second TESS exposure. The optical transient has a magnitude of 16.40 ± 0.14 in the TESS band in this image. The magnitude falls to 16.50 ± 0.15 in the next exposure, and then 17.08 ± 0.25 mag in the third exposure. These values are in line with the upper limits of 16.2 (r) at T0+1 min, and 17.4 at T0+15 min from Klotz et al., GCN 37989.
This circular includes data collected with the TESS mission, obtained from the MAST data archive at the Space Telescope Science Institute (STScI). Funding for the TESS mission is provided by the NASA Explorer Program. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
GCN Circular 38029
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 5.6 ks of XRT data for GRB 241030B, from 168 s to 51.2
ks after the BAT trigger. The data are entirely in Photon Counting
(PC) mode.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.17 (+/-0.07).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.00 (+0.31, -0.28). The
best-fitting absorption column is 2.9 (+1.3, -0.9) x 10^21 cm^-2,
consistent with the Galactic value of 2.0 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.5 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.9 (+1.3, -0.9) x 10^21 cm^-2
Galactic foreground: 2.0 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.00 (+0.31, -0.28)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01263840.
This circular is an official product of the Swift-XRT team.
GCN Circular 38024
This was a duplicate submission of GCN 38023.
GCN Circular 38023
Zh. Abdullayev (NU), Zh. Maksut (NU), T. Komesh (NU), B. Grossan (UCB, NU), D. Berdikhan (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 241030B 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 20:15:59 UT on 2024-10-30, 1.7 h after the BAT trigger. Observations were made in partly cloudy conditions. No source consistent with the XRT (P.A. Evans 2024, GCN Circ. 37983) was detected. We report the following results:
start time t-t0(s) end time UL g' UL r' exposure_time (s)
--------------------------------------------------------------
20:15:59 6100 20:16:59 19.2 19.0 60
start time is in UT. t-t0(s) gives the time since trigger, in seconds. UL g' and UL r' give the 5 sigma upper limit sensitivity in magnitudes, for images co-added to the given exposure time. The results in in the table corresponds to co-adds of an initial short exposure image sequence of 0.5 s (these sub-second exposures are read-noise suppressed by our EMCCD cameras, with high gain electron multiplication active). Calibration was done with the 3 bright Pan-STARRS catalog stars on our images.
----------------------------------
NU = Nazarbayev University, Astana, 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, Kazkhstan.
GCN Circular 38020
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 (Universita' degli Studi Di Salerno) report:
We performed follow-up observations of the field of GRB 241030B with the automated and remoted 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88).
Observations were started at 2024-10-30 21:55:28 UT, 3.33 hours after burst (Fermi-GBM team, GCN 37980; Swift trigger 1263840, GCN 37981 Klingler et al.; SVOM/ECLAIRs, GCN 37984 Zhao et al.) stacking 140x40s Rc-band CCD images.
In our preliminary analysis, we have not found any optical transient candidate within the error-box (2.4 arcmin.) of the Neil Gehrels Swift Observatory enhanced position (RA 03h 23m 10.19s, Dec. +34d 26m 49.2s - J2000) down to the following 3-sigma optical upper limits:
MJD Exp. Filter UL (3-sigma)
60614.4476 140x40s Rc > 20.91
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 fading detection and upper limits already reported (Fu et al., GCN 37985; Odeh et al., GCN 37986; Moskvitin et al., GCN 37987; Klotz et al., GCN 37989; Brivio et al., GCN 37991; Moskvitin et al., GCN 37995; Watson et al., GCN 37998; Qiu et al., GCN 37999; Hagio et al., GCN 38001; Tanvir et. al., GCN 38004; Strausbaugh et. al., GCN 38012; Swain et al., GCN 38013).
GCN Circular 38013
V. Swain, A.P. Saikia, T. Mohan, R. Kumar, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the field of GRB 241030B (Fermi GBM Team, GCN 37980, Klingler et al. GCN 37981) with 0.7m GROWTH-India Telescope (GIT) in g', r', and i' filters. We started the observation at 2024-10-30 18:42:39 UT, i.e., 8.3 mins after the Fermi GBM trigger. We took multiple exposures and obtained upper limits at the position reported by Fu et. al., (GCN 37985). The photometry results follow as:
------------------------------------------------------------------------------
| JD (mid) | t-t0 (mins) | Filter | Exposure (s) | Upper limit (AB) |
| ----------------- | ----------- |------- | ------------ | -------------- |
| 2460614.279618055 | 8.32 | r' | 20 | 18.9 |
| 2460614.281053241 | 10.38 | g' | 20 | 18.7 |
| 2460614.282048611 | 11.82 | i' | 30 | 18.0 |
| 2460614.434398148 | 231.2 | g' | 440 | 21.2 |
| 2460614.439745370 | 238.9 | r' | 440 | 21.3 |
| 2460614.445185185 | 246.7 | i' | 400 | 20.2 |
------------------------------------------------------------------------------
Our results are consistent with Fu et al.; (GCN 37985), Odeh et al.; (GCN 37986), Moskvitin et al.; (GCN 37987), Brivio et al.; (GCN 37991), Moskvitin et al.; (GCN 37995), Watson et al.; (GCN 37998), Qiu et al.; (GCN 37999), Hagio et al.; (GCN 38001), Tanvir et. al.; (GCN 38004), Breeveld et. al.; (GCN 38008), Strausbaugh et. al.; (GCN 38012).
The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular 38012
R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:
We observed the Fermi/Swift GRB 241030B field (Fermi GBM Team, GCN 37980; Klingler et al., GCN 37981) with the LCOGT 1-meter Sinistro instrument at the Teide Observatory, Tenerife site, on October 30, from 21:50 to 22:22 UT (corresponding to 3.27 to 3.8 hours after the GRB trigger time) with the sdss r and i filters.
We performed a series of 3x300s exposures in i- and r-bands. We do not detect a source within the enhanced Swfit XRT error region (Evans et al., GCN 37983) in either band. This result is consistent with fading from early optical detections (Fu et al., GCN 37985; Odeh et al, GCN 37986; Moskvitin et al., GCN 37987, Brivio et al., GCN 37991; Moskvitin et al., GCN 37995; Qiu et al., GCN 37999; Tanvir et al., GCN 38004; Breeveld et al., GCN 38008) and other optical upper limits (Klotz et al., GCN 37989; Hagio et al., GCN 38001).
The following 5-sigma upper limits are calculated using the PanSTARRS catalog as reference:
r > 22.5
i > 22.0
These magnitudes are not corrected for galactic extinction.
GCN Circular 38011
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), R. Gupta (GSFC),
N. J. Klingler (GSFC/UMBC/CRESSTII), 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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 241030B (trigger #1263840)
(Klingler, et al., GCN Circ. 37981). The BAT ground-calculated position is
RA, Dec = 50.787, 34.439 deg which is
RA(J2000) = 03h 23m 08.8s
Dec(J2000) = +34d 26' 21.9"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 11%.
The mask-weighted light curve shows a single-pulse structure that starts at
T-2 sec, peaks at T+1 sec, and ends at T+9 sec. T90 (15-350 keV) is
6.7 +- 1.6 sec (estimated error including systematics).
The time-averaged spectrum from T-1.58 to T+7.10 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.40 +- 0.16. The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.68 sec in the 15-150 keV band
is 3.2 +- 0.6 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/1263840
GCN Circular 38008
A. A. Breeveld (UCL-MSSL) and N. J. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 241030B 162 s after the BAT trigger (Klingler et al., GCN Circ. 37981).
The optical counterpart (Fu et al., GCN Circ. 37985; Odeh et al., GCN Circ. 37986; Moskvitin et al., GCN Circ. 37987; Brivio et al., GCN Circ. 37991; Moskvitin et.al GCN Circ. 37995 and Qui et al. GCN Circ. 37999) is detected in the initial UVOT exposure in the white filter only.
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 162 538 167 21.00 ± 0.30
v 395 4817 255 >19.4
b 494 857 58 >19.3
u 469 5380 203 >20.2
w1 444 5228 255 >21.1
m2 4822 5021 197 >19.7
w2 371 4612 255 >19.8
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.204 in the direction of the burst (Schlegel et al. 1998).
GCN Circular 38004
N. R. Tanvir (U. Leicester), C. C. Thoene (ASU-CAS, AbAO), J. P. U. Fynbo (DAWN/NBI), A. de Ugarte Postigo (LAM/OCA, CNRS), L. Izzo (INAF-OACn & DARK/NBI), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Martin-Carrillo (UCD), J. F. Agui Fernandez (CAHA), G. Lombardi (GTC), S. Geier (GTC) and G. Gómez Velarde (GTC) report:
We observed the optical counterpart (Fu et al., GCN 37985) of GRB 241030B (Fermi GBM team, GCN 37980; Klingler et al., GCN 37981; Zhao et al., GCN 37984) using OSIRIS+ on the 10.4 m GTC telescope, at the Roque de los Muchachos Observatory (La Palma, Spain). The observation consisted of 4 spectra of 1200 s each, obtained with grism R1000B, covering the spectral range between 3650 and 7800 AA, at a resolving power of 600.
The acquisition image, obtained on 2024-10-31 at 02:42:33 UT, 8.14 hr since the trigger, shows the afterglow at r(AB) = 23.53 +/- 0.12 mag, as compared to Pan-STARRS field stars.
The spectrum shows a faint continuum over the complete spectral range, though a drop in flux is observed blueward of ~4700 AA, suggesting the onset of the Lyman-alpha forest. No clear DLA trough is visible, but several, low S/N absorption features are present to the red of the drop, which we tentatively interpret as Si II 1526, Si IV 1393, C IV 1548,1550 (blended), Al II 1670, Al III 1854,1862 at z = 2.82, which we propose as the redshift of GRB 241030B.
GCN Circular 38002
SVOM/GRM team: Wen-Jun Tan, Chen-Wei Wang, Shi-Jie Zheng, Yong-Wei Dong, Jiang-Tao Liu, Jian-Chao Sun, Yue Huang, Jiang He, Min Gao, Hao-Xuan Guo, Lu Li, Yong-Ye Li, Hong-Wei Liu, Xin Liu, Hao-Li Shi, Li-Ming Song, You-Li Tuo, Wen-Long Zhang, Hao-Xi Wang, Jin Wang, Jin-Zhou Wang, Ping Wang, Rui-Jie Wang, Yu-Xi Wang, Yue 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, Yan-Qiu Zhang, Yan-Ting Zhang, Shu-Min Zhao, Xiao-Yun Zhao, Chao Zheng (IHEP), Maria-Grazia Bernardini (LUPM/INAF-OAB), Laurent Bouchet (IRAP), David Corre (CEA), Tais Maiolino (LUPM), Frédéric Piron (LUPM), Stéphane Schanne (CEA), Jingwei Wang (IAP), JeanLuc Attéia (IRAP)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Olivier Godet (IRAP), 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), Shao-Lin Xiong (IHEP), Bing Zhang (UNLV)
report on behalf of the SVOM team:
During the commissioning phase, the SVOM/GRM was triggered in-flight by GRB 241030B at 2024-10-30T18:34:22.000 UT (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN 37980), Swift/BAT (Klingler et al, GCN 37981), Swift/XRT (Evans et al, GCN 37983) and SVOM/ECLAIRs (Zhao et al, GCN 37984).
The real-time alert data and light curves of SVOM/GRM were downlinked to the ground through the VHF system with low latency. With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 6.8 +1.5/-0.5 s. The SVOM/GRM on-ground position is consistent with the SVOM/ECLAIRs on-board localization.
The GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb241030B.png
This burst is located at about 29.4 degrees from the SVOM optical axis.
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: Wen-Jun Tan (IHEP)(tanwj@ihep.ac.cn)
GCN Circular 38001
H. Hagio, Y. Kubo, N. Higuchi, I. Takahashi, M. Niwano, M. Sasada, S. Hayatsu, H. Seki, S. Joshima, Y. Yatsu and N. Kawai (Science Tokyo) report on behalf of the MITSuME collaboration:
We observed the field of GRB 241030B (Fermi GBM Team, GCN 37980, Klingler et al. GCN 37981) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno.
The observation started at 2024-10-30 18:44:33.72 UT (10.2 minutes after the Swift/BAT trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the enhanced Swift/XRT error region(Evans et al. GCN 37992). We obtained the 5-sigma limits of the stacked images as follows.
T0+[min] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
15.9 | 2024-10-30 18:50:13.75 | 480 | g'>18.7, Rc>18.6, Ic>18.1
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the trigger
T-EXP: Total Exposure time
We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ; https://github.com/MNiwano/Eclaire).
GCN Circular 37999
SVOM/VT commissioning team: Y. L. Qiu, H. L. Li, L. P. Xin, C. Wu, X. H. Han, J. Wang, W. J. Xie, H. B. Cai, Y. Xu, Y. J. Xiao, P. P. Zhang, J. S. Deng, L. Lan, X. M. Lu, R. S. Zhang, (NAOC), J. Zhang, L. J. Dan, G. Y. Zou, C. J. Wang, Y. F. Du, C. Huang (XIOPM), H. Zhou (PMO).
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Olivier Godet (IRAP), 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), Shao-Lin Xiong (IHEP), Bing Zhang (UNLV)
report on behalf of the SVOM team:
VT started to observe the field of GRB 241030B (Fermi GBM team, GCN 37980; Klingler et al., GCN 37981; Evans, GCN 37983; Zhao et al., GCN 37984; Evans et al., GCN 37992; Mukherjee et.al, GCN 37996) after the automatic slew of the platform. The VT conducted observation in B band (400nm-650nm) channel.
The optical counterpart (Fu et al., GCN 37985; Odeh et al., GCN 37986; Brivio et al., GCN 37991; Moskvitin et al., GCN 37987; Moskvitin et.al GCN 37995) was detected at 2024-10-30T18:39:52 in VT_B band image with a exposure time of 100s . The brightness was 19.47+-0.05 mag, at a mid time of 382 s after the burst.
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 was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS.
GCN Circular 37998
Alan M. Watson (UNAM), S. Antier (OCA), Stéphane Basa (UAR Pytheas),
William H. Lee (UNAM), Dahlia Akl (AUS), Jean-Luc Atteia (IRAP), Nathaniel
R. Butler (ASU), Damien Dornic (CPPM), J.-G. Ducoin (CPPM), Francis Fortin
(IRAP), Simona Lombardo (LAM), Francesco Magnani (CPPM), and Margarita
Pereyra (UNAM) report:
We imaged the field of GRB 241030B detected by Fermi/GBM, Swift/BAT,
Swift/XRT, and SVOM/ECLAIRs (Fermi GBM Team, GCN Circ. 37980; Klingler et
al., GCN Circ. 37981; Zhao et al., GCN Circ. 37984) during the
commissioning of the COLIBRÍ (SVOM/F-GFT) telescope at the Observatorio
Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico.
We observed with the engineering test camera in a red filter that
approximates SDSS r. We observed from 2024-10-31 03:51 to 05:46 UTC (9.3 to
11.2 hours after the trigger) and obtained 5160 seconds of exposure. The
data were reduced using custom software and then analyzed and calibrated
against the PS1 catalog using the STDWeb service (Karpov et al., 2022).
We do not detect the optical counterpart (Fu et al., GCN Circ. 37985; Odeh
et al., GCN Circ. 37986; Moskvitin et al., GCN Circ. 37987; Brivio et al.,
GCN Circ. 37991; Moskvitin et al., GCN Circ. 37995) with a 3-sigma limiting
AB magnitude of:
r > 23.2
We warmly thank the COLIBRÍ engineering team and the staff of the
Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir.
GCN Circular 37996
O. Mukherjee (USRA), S. Dalessi (UAH), S. Bala (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 18:34:20.39 UT on 30 October 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB241030B (trigger 752006065/241030774).
which was also detected by Swift/BAT (N. Klingler et al. 2024, GCN 37981),
and SVOM/ECLAIRs (D. Zhao et al. 2024, GCN 37984).
The Fermi GBM on-ground location is consistent with the Swift/BAT position.
The angle from the Fermi LAT boresight is 54 degrees.
The GBM light curve consists of a single bright peak with a duration (T90)
of about 6.8 s (50-300 keV). The time-averaged spectrum
from T0-1.0 to T0+9.2 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.04 +/- 0.07 and the cutoff energy,
parameterized as Epeak, is 200 +/- 20 keV.
The event fluence (10-1000 keV) in this time interval is
(3.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.83 s in the 10-1000 keV band is 6.7 +/- 0.2 ph/s/cm^2.
A Band function fits the spectrum equally well with
Epeak = 190 +/- 26 keV, alpha = -1.03 +/- 0.08 and beta = -2.81 +/- 1.
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 37995
A. S. Moskvitin, A. S. Vinokurov (SAO RAS), A. S. Pozanenko (IKI),
N. Pankov (IKI, HSE) report on behalf of the GRB follow-up team.
We observed the field of GRB 241030B (Fermi GBM team, GCN 37980;
Klingler et al., GCN 37981; Evans, GCN 37983; Zhao et al., GCN 37984;
Evans et al., GCN 37992), with the 6-m telescope of SAO RAS equipped
with the focal reducer Scorpio-I. We obtained quasi-simultaneous
16 x 30 sec images both in B and Rc bands on October 30.
The OT (Fu et al., GCN 37985; Odeh et al., GCN 37986; Brivio et al.,
GCN 37991; Moskvitin t al., GCN 37987) is clearly detected in the Rc
stacked frame, but not presented in the B stacked frame:
UT_start--UT_end t_mid - T0, h filter OT_mag limit (3sigma)
20:17:39--20:43:25 1.9367 R 22.10 +/- 0.08 24.0
20:18:28--20:44:15 1.9504 B n/d 24.0
This preliminary photometry is based on nearby PS1 stars (magnitudes
converted with Lupton 2005 equations) and not corrected
for the Galaxy extinction.
We also obtained 2 x 1200 sec spectrum with VPHG550G grism
(3500--7500 AA, FWHM resolution ~ 10A) on October 30,
19:34:07--20:14:23 UT (T-mid - T0 = 1.3319 hours).
In the spectrum we do not find a continuum lower than 5200A.
Due to non-detection in B filter and absence of continuum
we conclude that redshift of the GRB z >~ 3.3.
GCN Circular 37992
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1712 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 241030B, 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 = 50.79245, +34.44700 which is equivalent
to:
RA (J2000): 03h 23m 10.19s
Dec (J2000): +34d 26' 49.2"
with an uncertainty of 2.4 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 37991
R. Brivio (INAF-OAB), D.B. Malesani (DAWN/NBI and Radboud Univ.), Y.-D. Hu (INAF-OAB), P. D'Avanzo (INAF-OAB), A. Reguitti (INAF-OAB / INAF-OAPd), A. Melandri (INAF-OAR), M. Ferro (INAF-OAB), L. Tomasella (INAF -OAPd), E. Cappellaro (INAF -OAPd) report on behalf of the CIBO collaboration:
We carried out follow-up optical observations of GRB 241030B detected by Fermi (Fermi GBM team, GCN 37980