GRB 241002C
GCN Circular 37674
Subject
GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
Date
2024-10-02T10:21:39Z (8 months ago)
From
Stéphane Schanne at CEA Paris-Saclay/IRFU <s.schanne@cea.fr>
Via
Web form
GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
SVOM/ECLAIRs Commissioning Team: Frédéric Chateau, Stéphane Schanne, Nicolas Dagoneau, Hervé Le Provost (CEA), Wenjin Xie, Donghua Zhao (NAOC), Jean-Luc Atteia, Laurent Bouchet, Sebastien Guillot, Juliette Alaux, Hui Yang (IRAP), Tais Maiolino (LUPM), Floriane Cangemi (APC), Karine Mercier, Marie-Claire Charmeau, Stefano Crepaldi (CNES)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Olivier Godet (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/ECLAIRs telescope triggered and located a long soft transient, labelled GRB 241002C (sbsb24100203) at 2024-10-02T09:20:48 UT (Tb).
The following trigger information was received on the ground with low-latency by the SVOM VHF Alert Network. The burst was detected by the Image Trigger (IMT) which sent 3 Alerts in the 5-8 keV energy band. The best Alert has a signal-to-noise ratio of 8.9 over a time window of 655.36 s starting at Tb. The image transmitted shows a clean point-like source.
The event location is RA, Dec = 62.45, -7.91 (J2000) (or L, B = 159.79, -39.36).
The statistical uncertainty on this position is 9.5 arcminutes, to which we recommend adding 10 arcminutes of systematic uncertainty in quadrature.
SVOM did not slew to the burst since automated slewing was not enabled.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by APC, CEA, CNES, and IRAP.
The SVOM point of contact for this burst is: b.cordier AT cea.fr.
GCN Circular 37688
Subject
GRB 241002C : MITSuME Akeno optical upper limits
Date
2024-10-03T08:01:43Z (8 months ago)
From
joshima@hp.phys.titech.ac.jp
Via
Web form
S.Joshima, M.Niwano, I. Takahashi, M. Sasada, N. Higuchi, S. Hayatsu, H. Seki, Y. Kubo, H. Hagio, Y. Yatsu and N. Kawai (Science Tokyo) report on behalf of the MITSuME collaboration:
We observed the field of GRB 241002C (SVOM/ECLAIRs Team, GCN 37674) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno.
The observation started at 2024-10-02 13:51:00 UT (4.5 hrs after the SVOM/ECLAIRs trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the SVOM/ECLAIRs error region. We obtained the 5-sigma limits of the stacked images as follows.
T0+[hrs] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
5.6 | 2024-10-02 15:31:14.67 | 3240 | g'>18.9, Rc>19.1, Ic>18.7
------------------------------------------------------------------------------------------------
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 37690
Subject
GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
Date
2024-10-03T09:47:13Z (8 months ago)
Edited On
2024-10-03T14:24:44Z (8 months ago)
From
Diego Gotz at CEA <diego.gotz@cea.fr>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Diego Gotz at CEA <diego.gotz@cea.fr>
Via
Web form
SVOM/MXT Commissioning Team: D. Götz (CEA Irfu/DAp), A. Fort, J. Joubert, K. Mercier, S. Crepaldi (CNES), F. Robinet, N. Leroy (IJCLab), P. Ferrando, A. Meuris, M. Moita, C. Plasse, A. Sauvageon, (CEA), P. Maggi, L. Michel (ObAS)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Olivier Godet (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), Shaolin Xiong (IHEP), Bing Zhang (UNLV)
Report on behalf of the SVOM team:
MXT observed the field fo GRB241002C (Schanne et al., GCN 37674) as a TOO from 2024 October 3rd at 02:29 UTC to 05:53 UTC, 17 hours after T0.
A faint source is detected by the on board software at RA: 62.410 Dec =- 7.896 with a 90% c.l. error of 1 arc minute. Further results will be given once the full telemetry is received and analyzed.
We note that the position of 1RXS J040940.8-075327 (V* EI Eri) is compatible with the MXT error box. Further observations will be needed to assess the variability of the source. Observations by other X-ray telescopes are encouraged.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. MXT was developed jointly by CEA, CNES, University of Leicester, IJCLab and MPE.
GCN Circular 37698
Subject
GRB 241002C: Swift ToO observations
Date
2024-10-03T16:43:38Z (8 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the SVOM/ECLAIRs GRB 241002C.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021720
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the SVOM/ECLAIRs event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 37702
Subject
GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
Date
2024-10-03T19:31:51Z (8 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
SVOM/ECLAIRs-trigger named GRB 241002C (GCN Circ. 37674), collecting
1.7 ks of Photon Counting (PC) mode data between T0+113.0 ks and
T0+114.8 ks.
The known RS CVn variable star, EI Eri, is clearly detected as a bright
X-ray source inside the ECLAIRs error region, at a mean count rate of
1.51 +/- 0.06 ct s^-1. Gotz et al. (GCN 37690) noted that the position
of this source was compatible with the SVOM-MXT error box.
No additional uncatalogued X-ray sources have been detected within the
error region. We therefore conclude that GRB 241002C is not a GRB, but
was instead due to EI Eri (also known as 1RXS J040940.8-075327 and 4XMM
J040940.8-075332).
The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021720.
This circular is an official product of the Swift-XRT team.
GCN Circular 37706
Subject
GRB 241002C: SVOM/C-GFT optical upper limit
Date
2024-10-04T06:03:53Z (8 months ago)
From
Chao Wu at NAOC <cwu@nao.cas.cn>
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), 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)
We observed the field of the GRB 241002C (sb24100203) detected by SVOM/ECLAIRs(Chateau et al., GCN 37674) starting at 2024-10-02T15:37:13 UT, ~6.27 hr after the burst trigger with C-GFT (Chinese Ground Follow-up Telescope in SVOM mission) in the commissionig phase. 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. We obtained stacked images of g: 36x30s, r: 36x30s and i: 36x30s. No any uncatalogued optical source detected within the SVOM/ECLAIRs error region down to the limiting magnitude (3 sigma) of mag_g=19.44, mag_r=19.91, and mag_i=19.51 . It is consistent with the results reported by Joshima et al. (GCN 37688) and Page et al. (GCN 37702).
The photometry was calibrated with nearby stars in Pan-STARRS 1 .
We thank the observation assistants Bowen Li and Guangsheng Zhang at Jilin observatory for their excellent support.