Guowang Du (SWIFAR, YNU), Weikang Lin (SWIFAR, YNU), Brajesh Kumar (SWIFAR,=
YNU), Yaosong Yu (SWIFAR, YNU), Yehao Cheng (SWIFAR, YNU), Xinlei Chen (SW=
IFAR, YNU), Yu Pan (SWIFAR, YNU), Xingzhu Zou (SWIFAR, YNU), Jinghua Zhang =
(SWIFAR, YNU), Yuanpei Yang (SWIFAR, YNU), Yuan Fang (SWIFAR, YNU), Xuhui H=
an (NAOC), Pinpin Zhang (NAOC), Liping Xin (NAOC), Chao Wu (NAOC), Xiangkun=
Liu (SWIFAR, YNU), Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephi=
sto Team:
=20
The 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan Un=
iversity located at Lijiang Observatory was triggered to observe GRB 241112=
B (sb24111201) detected by SVOM/ECLAIRs and SVOM/GRM (Yang et al., GCN 3817=
3; Liu et al., GCN 38180). The observations were started at 11:46:00 (UT) o=
n 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 G=
RB 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 Me=
phisto data and identified the optical counterpart at this reported locatio=
n. Initially, we missed this source while manually searching within the SVO=
M/ECLAIRs localization region due to its proximity to a faint, extended sou=
rce in the DESI DR10 image and the lack of template subtraction, which led
to confusion in identifying new transient sources.=20
Preliminary photometry of the optical afterglow of GRB 241112B (without tem=
plate 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 ima=
ging the same field of view in three optical bands simultaneously. It provi=
des real-time, high-quality colors of stellar objects. The on-site telescop=
e assemblage and commissioning were carried out in September 2022. The firs=
t light in all three channels was achieved on 2023 December 21.=20
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GCN Circular #38184
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/uploads/https://zenodo.org/records/14110881
[1] Goldstein et al. 2019 arXiv:1903.12597
GCN Circular #38188
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
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
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 Li=
u, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team:
We re-observed the field of GRB 241112B (sb24111201) detected by SVOM/ECLAI=
Rs 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 Universi=
ty located at Lijiang Observatory. Multiple frames of 300 s were obtained i=
n 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. Th=
e optical afterglow candidate (Qui et al., GCN 38179; Turpin et. al, GCN 38=
181; Osborne et. al, GCN 38182; Du et. al, GCN 38183) is faintly detected i=
n 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 th=
e Mephisto observations and estimated magnitudes (Du et. al, GCN 38183), we=
obtained the temporal decay indexes as alpha =3D 0.93 and 1.02 for r band =
and i band, respectively, where alpha is defined as Flux=3D(t-T0)^-alpha. T=
he 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 ima=
ging the same field of view in three optical bands simultaneously. It provi=
des real-time, high-quality colors of stellar objects. The on-site telescop=
e assemblage and commissioning were carried out in September 2022. The firs=
t light in all three channels was achieved on 2023 December 21.=20
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