GRB 241112B
GCN Circular 38173
Subject
GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
Date
2024-11-12T11:28:07Z (7 months ago)
From
Stéphane Schanne at CEA Paris-Saclay/IRFU <s.schanne@cea.fr>
Via
Web form
SVOM/ECLAIRs Commissioning Team: Hui Yang, Marius Brunet, Jean-Luc Atteia, Laurent Bouchet, Sebastien Guillot, Juliette Alaux (IRAP), Stéphane Schanne, Frédéric Chateau, Nicolas Dagoneau, Hervé Le Provost (CEA), Wenjin Xie, Donhua Zhao (NAOC), 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 the long GRB 241112B (sb24111201) at 2024-11-12T10:57:21 UT (Tb), which was also detected by SVOM/GRM.
The following trigger information was received on the ground with low-latency by the SVOM VHF Alert Network. The burst was detected by both the on-board Count-Rate Trigger (CRT) and Image Trigger (IMT) and 19 alerts were received. The best detection is obtained by CRT with a signal-to-noise ratio of 23.1 in the 8-50 keV energy band over a time window of 10.24 s starting at Tb. The light-curve shows two main peaks of about 10 s duration each, the first is mainly seen below 50 keV, the second below 20 keV.
The GRB localization is RA, Dec = 29.055, 9.146 (J2000).
The statistical uncertainty on this position is 3.7 arcminutes, to which we recommend adding 2 arcminutes of systematic uncertainty in quadrature.
SVOM performed an automatic slew to the burst.
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: stephane.schanne AT cea.fr
GCN Circular 38174
Subject
GRB 241112B: Swift ToO observations
Date
2024-11-12T13:58:16Z (7 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 241112B.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021730
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 38175
Subject
GRB 241112B: GOTO optical upper limits
Date
2024-11-12T14:02:37Z (7 months ago)
From
Amit Kundu at Royal Holloway - U. of London, UK <amitkundu515@gmail.com>
Via
Web form
A. Kumar, K. Ulaczyk, D. O'Neill, G. Ramsay, B. Godson, B. P. Gompertz, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, F. Jimenez-Ibarra, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, E. Palle and D. Pollacco report on behalf of the GOTO collaboration:
The Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) observed the field of SVOM/ECLAIRs detected GRB 241112B (Yang et al., GCN 38173) at 12:35:35 UT on 2024-11-12 (around 1.637 hours post trigger). The observation was taken by GOTO-S (at Siding Spring Observatory in Australia), and consisted of 3x60s exposures in the GOTO L-band (400-700 nm).
Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations of the same pointings.
No new optical source within the SVOM/ECLAIRs localisation region is identified to a 3-sigma limiting magnitude of L > 19.1. The shallower upper limit results from the moon's lower angle relative to the source field.
Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.
GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).
GCN Circular 38176
Subject
GRB 241112B: Mephisto optical upper limits
Date
2024-11-12T14:52:04Z (7 months ago)
From
Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn>
Via
Web form
Guowang Du (SWIFAR, YNU), Weikang Lin (SWIFAR, YNU), Brajesh Kumar (SWIFAR, YNU), Yaosong Yu (SWIFAR, YNU), Yehao Cheng (SWIFAR, YNU), Xinlei Chen (SWIFAR, YNU), Yu Pan (SWIFAR, YNU), Xingzhu Zou (SWIFAR, YNU), Jinghua Zhang (SWIFAR, YNU), Yuanpei Yang (SWIFAR, YNU), Yuan Fang (SWIFAR, YNU), Xuhui Han (NAOC), Pinpin Zhang (NAOC), Liping Xin (NAOC), Chao Wu (NAOC), Xiangkun Liu (SWIFAR, YNU), Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team:
The 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory was triggered to observe GRB 241112B (sb24111201) detected by SVOM/ECLAIRs and SVOM/GRM (Yang et al., GCN 38173). The observations were started at 11:46:00 (UT) 2024-11-12 (~0.8 hr after SVOM trigger) and multiple frames were obtained in uvgriz bands. No new candidate was detected in the stacked images, consistent with Kumar et al. (GCN 38175). The 3-sigma upper limits are the following:
Mid-Time(UT) Band Exp(s) Lim-mag(AB)
2024-11-12T11:50:43 u 180*3 >21.21
2024-11-12T12:01:14 v 180*3 >21.50
2024-11-12T11:50:40 g 50*9 >21.84
2024-11-12T12:01:12 r 50*9 >22.10
2024-11-12T11:49:55 i 79*5 >21.16
2024-11-12T12:01:16 z 79*6 >20.47
--------------------------------------------------------------------------
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 38179
Subject
GRB 241112B: SVOM/VT afterglow detection
Date
2024-11-12T16:52:30Z (7 months ago)
From
Liping Xin at NAOC, SVOM <xlp@nao.cas.cn>
Via
Web form
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), C. W. Wang(IHEP), W. J. Tan(IHEP), R. C. Chen(NJU).
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:
The GRB 241112B (Yang et al., GCN 38173) was observed by on-board VT after the automatic slew of the platform. The VT conducted observations in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously.
An uncatalogued source was detected in data processing results on-board in VT_B and VT_R band images within the errorbox of Eclairs (Yang et al., GCN 38173), and further confirmed with the data downlinked via X band. The source is located near a faint extended source in DESI Dr10 catalog, and its brightness was fading for 3.5 magnitudes in VT_B images in the initial 5.5 hours.
The magnitude was VT_B=18.24 mag and VT_R=17.70 mag in AB magnitude at 2024-11-12T11:04:59 UT, about 7.6 min after the burst.
The coordinates are R.A.= 01:56:09.270, DEC. = 09:06:27.91, Error = 0.1 arcseconds, J2000.
We proposed that this source is the optical counterpart of 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 38180
Subject
GRB 241112B: SVOM/GRM observation
Date
2024-11-12T17:16:45Z (7 months ago)
From
zhengchao_astro@foxmail.com
Via
Web form
SVOM/GRM team: Jia-Cong Liu, 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, Wen-Jun Tan, Yue Wang, 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, Yan-Qiu Zhang, Yan-Ting Zhang, Shu-Min Zhao, Xiao-Yun Zhao, Jin-Peng Zhang, 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 detected GRB 241112B at 2024-11-12T10:57:21 UT (T0), which was also observed by SVOM/ECLAIRs (Yang et al, GCN 38173).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of one pulse, with a T90 of 7.0 +1.6/-0.8 s (15-550 keV). This pulse is followed by a much weaker and softer (<25 keV) pulse that is consistent with the ECLAIRs observation. This burst is located at about 22.3 degrees from the SVOM optical axis.
The GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb241112B.png
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: Jia-Cong Liu (IHEP)(liujiacong@ihep.ac.cn)
GCN Circular 38181
Subject
GRB 241112B: LCO optical detection of the SVOM/VT candidate
Date
2024-11-12T18:18:50Z (7 months ago)
From
Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>
Via
Web form
D. Turpin (CEA/Irfu), A. Saccardi (CEA/Irfu, GEPI/Obs. de Paris), J. T. Palmerio (CEA/Irfu, GEPI/Obs. de Paris), S. Vergani (GEPI/Obs. de Paris), S. Basa (OSU Pytheas, LAM), E. LeFloc'h (CEA Paris-Saclay, DAp/AIM) on behalf of a larger collaboration.
We observed the field of GRB 241112B, detected by SVOM/ECLAIRs (Yang et al., GCN 38173) with the LCO 0.4m telescope at the Haleakala Observatory and the 1m telescope equipped with the Sinistro instrument at Siding Spring Observatory. Our observation started at 2024-11-12T11:41:20.771 (T - TGRB ~ 44min) with a series of 5x120s (sdssr, 0.4m), 4x180s (sdssi, 0.4m) and 5x120s (sdssr, 1.0m) exposures.
At the position of the optical afterglow candidate reported by SVOM/VT (Qiu et al., GCN 38179), we detect a faint optical source at the detection limit of our single exposure frames which does not appear in the USNOB1.0 and SDSS DR12 catalogs. Note that the faint red extended source present in the Legacy Survey DR10 catalog, mentioned by Qiu et al., GCN 38179, is about 3 arcsecond away from the position of the optical counterpart.
From our first exposure, we derive the following magnitude r = 19.0 +/- 0.3 (AB) at T-TGRB = 45 min (mid time).
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101004719
GCN Circular 38182
Subject
GRB 241112B: Swift-XRT afterglow detection
Date
2024-11-12T19:15:04Z (7 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), M.
Ferro (INAF-OAB), M. A. Williams (PSU), S. Dichiara (PSU), J.A. Kennea
(PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT
team:
Swift-XRT has performed follow-up observations of the
SVOM/ECLAIRs-detected burst GRB 241112B, collecting 2.5 ks of Photon
Counting (PC) mode data between T0+11.0 ks and T0+17.6 ks.
Two uncatalogued X-ray sources are detected consistent with being
within 414 arcsec of the SVOM/ECLAIRs position, of which one ("Source
1") is above the LSXPS 3-sigma upper limit at this position, and is
therefore likely the GRB afterglow. The position of this source is RA,
Dec=29.0386, +9.1080 which is equivalent to:
RA (J2000): 01:56:9.26
Dec(J2000): +09:06:29.0
with an uncertainty of 4.1 arcsec (radius, 90% confidence). This
position is 2.5 arcmin from the SVOM/ECLAIRs position. The source has
a mean count rate of 2.1e-02 ct/sec; we cannot determine at the present
time whether it is fading.
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.9 (+0.9, -0.5). The
best-fitting absorption column is 9 (+30, -3) x 10^20 cm^-2,
consistent with the Galactic value of 5.6 x 10^20 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.3 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 9 (+30, -3) x 10^20 cm^-2
Galactic foreground: 5.6 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.9 (+0.9, -0.5)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021730.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021730.
This circular is an official product of the Swift-XRT team.
GCN Circular 38183
Subject
GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
Date
2024-11-12T20:22:30Z (7 months ago)
From
Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn>
Via
Web form
Guowang Du (SWIFAR, YNU), Weikang Lin (SWIFAR, YNU), Brajesh Kumar (SWIFAR, YNU), Yaosong Yu (SWIFAR, YNU), Yehao Cheng (SWIFAR, YNU), Xinlei Chen (SWIFAR, YNU), Yu Pan (SWIFAR, YNU), Xingzhu Zou (SWIFAR, YNU), Jinghua Zhang (SWIFAR, YNU), Yuanpei Yang (SWIFAR, YNU), Yuan Fang (SWIFAR, YNU), Xuhui Han (NAOC), Pinpin Zhang (NAOC), Liping Xin (NAOC), Chao Wu (NAOC), Xiangkun Liu (SWIFAR, YNU), Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team:
The 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory was triggered to observe GRB 241112B (sb24111201) detected by SVOM/ECLAIRs and SVOM/GRM (Yang et al., GCN 38173; Liu et al., GCN 38180). The observations were started at 11:46:00 (UT) on 2024-11-12 (~0.8 hr after SVOM trigger) and multiple images were obtained in uvgriz bands (as mentioned in Du et al., GCN 38176).
Based on the precise localization of the optical afterglow counterpart of GRB 241112B provided by SVOM/VT (Qiu et al., GCN 38179) and other facilities (Turpin et al., GCN 38181; Osborne et al., GCN 38182), we revisited the Mephisto data and identified the optical counterpart at this reported location. Initially, we missed this source while manually searching within the SVOM/ECLAIRs localization region due to its proximity to a faint, extended source in the DESI DR10 image and the lack of template subtraction, which led to confusion in identifying new transient sources.
Preliminary photometry of the optical afterglow of GRB 241112B (without template subtraction) in the griz bands and 3-sigma upper limits in the u and v bands are as follows:
Obs-start time band Exp(s) Mag (AB)
2024/11/12 11:46:00 i 50*1 18.71 +/- 0.10
2024/11/12 11:46:00 g 50*1 19.49+/- 0.31
2024/11/12 11:56:31 r 79*1 19.36 +/- 0.25
2024/11/12 11:56:31 z 79*1 18.90+/- 0.26
2024/11/12 11:46:00 u 180*3 >21.21
2024/11/12 11:56:31 v 180*3 >21.50
--------------------------------------------------------------------------
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 38184
Subject
Fermi-GBM Sub-Threshold Detection of GRB 241112B
Date
2024-11-12T22:00:20Z (7 months ago)
Edited On
2024-11-12T22:14:22Z (7 months ago)
From
Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>
Via
Web form
O.J. Roberts (USRA/NASA-MSFC) and E. Burns (LSU) reports on behalf of the Fermi-GBM Team:
SVOM detected GRB 241112B on 2024-11-12 at 10:57:21 UTC (i.e., Schanne et al., GCN #38173). There was no Fermi-GBM onboard trigger around this event time. An automated, blind search for gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no candidates.
The GBM Targeted Search [1], the most sensitive, coherent search for GRB-like signals, identified an unambiguous transient starting around the SVOM trigger time most significantly on the 16.384 s timescale, with a LogLR = 21.10. The Fermi-MET of the start time of this transient is 753101846.0 s. Using the standard search protocol, the Targeted Search localization was found to be RA=25.7 deg., Dec.= 32.8 deg., and an error of 31 deg. (90 % confidence level, includes the systematic error), at a SNR of 7.4.
Additionally, the GBM Targeted Search event was found with the highest significance using a "normal" spectrum (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.
The Targeted Search data release product for this event can be found here: https://zenodo.org/records/14110881
[1] Goldstein et al. 2019 arXiv:1903.12597
GCN Circular 38188
Subject
GRB 241112B: AbAO optical upper limit
Date
2024-11-13T03:21:14Z (7 months ago)
From
Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>
Via
legacy email
N. Pankov (HSE, IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO) report
on behalf of IKI-GRB-FuN:
We observed the field of GRB 241112B (SVOM/ECLAIRs Commissioning Team &
SVOM JSWG, GCN 38173; Evans, GCN 38174; Kumar et. al, GCN 38175; Du et. al,
GCN 38176; SVOM/VT commissioning team & SVOM JSWG, GCN 38179; SVOM/GRM team
& SVOM JSWG, GCN 38180; Turpin et. al, GCN 38181) with 70-cm AS-32
telescope of Abastumani observatory (AbAO). The observations began on
2024-11-12 at 15:03:45 UT. In total, the series of 101x60 s frames was
taken in the R-filter using CCD-photometer FLI PL4240. We do not detect the
optical afterglow (SVOM/VT commissioning team & SVOM JSWG, GCN 38179;
Turpin et. al, GCN 38181).
The preliminary photometry is as follows:
Date UTstart Exptime t-T0 Filter OT Err UL
(s) (mid, days) (3sigma)
2024-11-12 15:03:45 98*60 0.205139 R n/d n/d 19.6
The magnitudes were calibrated using nearby stars of USNO-B1.0 (R2
magnitudes).
RA Dec R2
01:56:20.7 +09:09:01.4 14.86
01:56:40.2 +09:10:09.0 15.24
GCN Circular 38199
Subject
GRB 241112B: GMG Optical Upper Limit
Date
2024-11-13T14:02:50Z (7 months ago)
From
wangbaiting@ynao.ac.cn
Via
Web form
B.-T. Wang, R.-Z. Li, F.-F. Song, J. Mao, H.-C. Feng and J.-M. Bai (YNAO, CAS) report:
We observed the field of GRB 241112B (SVOM/ECLAIRs team, GCN 38173; Evans, GCN 38174; Kumar et. al, GCN 38175; Du et. al, GCN 38176; SVOM/VT team, GCN 38179; SVOM/GRM team, GCN 38180; Turpin et. al, GCN 38181; Osborne et. al, GCN 38182; Du et. al, GCN 38183; Pankov et.al, GCN 38184) with the GMG-2.4m telescope at the Lijiang Observatory. The observation began at 2024-11-12T16:42:20, about 5.75 hours after the trigger.
No new uncataloged optical counterpart was detected within the SVOM/VT error circle (GCN 38179). It should be noted that due to the proximity and brightness of the Moon on the observational night, the optical signal from the GRB 241112B may have been affectd by the moonlight.
The preliminary photometry is as follows:
-----------------------------------------------------------------------------
UT EXP(s) filter mag
-----------------------------------------------------------------------------
2024-11-12T16:42:20 600 sdss-r >21.4
-----------------------------------------------------------------------------
The magnitudes were calibrated using nearby stars of Pan-STARRS DR1 field and without corrections for Galactic extinction.
We acknowledge the staff at the Lijiang Observatory for conducting the observation.
GCN Circular 38277
Subject
GRB 241112B: Mephisto further optical observations
Date
2024-11-19T09:08:20Z (6 months ago)
From
Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn>
Via
Web form
Xingzhu Zou, Brajesh Kumar, Yehao Cheng, Yuanpei Yang, Guowang Du, Weikang Lin, Yaosong Yu, Xinlei Chen, Yu Pan, Jinghua Zhang, Yuan Fang (all SWIFAR, YNU), Xuhui Han, Pinpin Zhang, Liping Xin, Chao Wu (all NAOC), Xiangkun Liu, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team:
We re-observed the field of GRB 241112B (sb24111201) detected by SVOM/ECLAIRs and SVOM/GRM (Yang et al., GCN 38173; Liu et al., GCN 38180) with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. Multiple frames of 300 s were obtained in uvgriz bands between 16:41:28 - 17:15:14 UT on 2024-11-12 (~5.7 hr after the trigger), although affected with high background due to moon light. The optical afterglow candidate (Qui et al., GCN 38179; Turpin et. al, GCN 38181; Osborne et. al, GCN 38182; Du et. al, GCN 38183) is faintly detected in our stacked r and i band images but not in other bands. The estimated PSF photometric magnitudes and the 3-sigma upper limits are below. Based on the Mephisto observations and estimated magnitudes (Du et. al, GCN 38183), we obtained the temporal decay indexes as alpha = 0.93 and 1.02 for r band and i band, respectively, where alpha is defined as Flux=(t-T0)^-alpha. The T0 is SVOM/ECLAIRs triggered time (Yang et al., GCN 38173).
Obs-start time band Exp(s) Mag (AB)
16:41:28T2024-11-12 u 300*3 >21.78
17:04:47T2024-11-12 v 300*3 >21.75
16:41:28T2024-11-12 g 300*3 >22.03
17:04:47T2024-11-12 r 300*3 21.00 +/- 0.14
16:41:28T2024-11-12 i 294*3 20.68 +/- 0.22
17:04:47T2024-11-12 z 294*3 >20.23
--------------------------------------------------------------------------
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.
--------------------------------------------------------------------------