Gamma-ray Burst 241001A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN Circular #37655
SVOM/ECLAIRs Commissioning Team: Nicolas Dagoneau, St=C3=A9phane Schanne, F= r=C3=A9d=C3=A9ric Chateau, Herv=C3=A9 Le Provost (CEA), Wenjin Xie (NAOC), = Jean-Luc Atteia, Laurent Bouchet, Sebastien Guillot, Juliette Alaux (IRAP),= Tais Maiolino (LUPM), Alexis Coleiro (APC), Karine Mercier, Marie-Claire C= harmeau, Stefano Crepaldi (CNES)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (I= HEP), St=C3=A9phane Basa (LAM), Olivier Godet (IRAP), Arnaud Claret (CEA), = Zi-Gao Dai (USTC), Fr=C3=A9d=C3=A9ric Daigne (IAP), Jin-Song Deng (NAOC), A= ndrea Goldwurm (APC), Diego G=C3=B6tz (CEA), Xu-Hui Han (NAOC), Cyril Lacha= ud (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 lo= cated a soft transient, called GRB 241001A (sb24100102) at 2024-10-01T17:08= :45 UT (TimtTb).
The following information from the ECLAIRs onboard trigger was received on = ground with low-latency by the SVOM VHF Alert Network. The burst was detect= ed by the Count-Rate Trigger (CRT) which produced 3 Alerts in the 5-8 keV e= nergy band. The best Alert has a signal-to-noise ratio of 7.8 over a time w= indow of 5.12 s starting at TimtTb. A clear point-like source is visible in= the deconvolved sky image downloaded.
The GRB location is RA, Dec =3D 20.42, -43.53 (J2000), far from the Galacti= c plane (L, B =3D 75.56, -72.49).
The statistical uncertainty on this position is 11.0 arcminutes, to which w= e 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 l= ed by the Chinese National Space Administration (CNSA), French Space Agency= (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to o= bserving gamma-ray bursts and other transient phenomena in the energetic un= iverse. ECLAIRs was developed jointly by APC, CEA, CNES, and IRAP.
The SVOM point of contact for this burst is: s.schanne AT cea.fr.
GCN Circular #37659
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the SVOM/ECLAIRs GRB 241001A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021719
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 #37664
I. Perez-Garcia, E. Fernandez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, S.-Y. Wu, G. Garcia-Segura and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland), M. Gritsevich (Univ. of Helsinki) and C. J. Perez del Pulgar (UMA, Malaga), on behalf of a larger collaboration, report:
Following the detection of the Oct 1 X-ray transient (dubbed GRB 241001A) by SVOM/ECLAIRS (SVOM team, GCNC 37665), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) observed the ECLAIRS X-ray transient location starting on Oct 1, 19:39 UT (~ 2.5 h after trigger). No new optical source is detected on the co-added images, covering a 15 arcmin radius around the ECLAIRS error box center down to 20.4 mag (clear filter).
We thank the staff at Boyden Observatory for their excellent support.
GCN Circular #37667
Luca Izzo (INAF/OACn) and Daniele B. Malesani (DAWN/NBI and Radboud Univ.) report:
We observed the field of the SVOM/ECLAIRs GRB 241001A (Dagoneau et al., GCN #37655) with the Sinistro instrument mounted on the 1-m telescope of the LCO network, located in Sutherland, South Africa. Observations started on 2024 October 1st at 18:40:35 UT (1.53 hr after the GRB trigger). We obtained a series of 3x120 s images in the SDSS-r filter and 5x120s images in the PS1-z filter.
The stacked r-band image covers the entire statistical ECLAIRs error region and it is slightly affected by a bad telescope tracking. We notice the presence of a faint source within the error box of the Swift-XRT afterglow candidate source no. 2 (Evans, GCN #37659) at coordinates (J2000.0):
```
RA = 01:22:12.71
Dec = -43:21:31.8
```
No source is visible in archival images from the Legacy Survey DR10 at this location.
We measure a preliminary magnitude of r = 20.7 +/- 0.2 mag (AB), calibrated against nearby stars from the Legacy Survey DR10 catalog. Further analysis is on-going.
Coupled with some evidence of fading of the X-ray counterpart (https://www.swift.ac.uk/ToO_GRBs/00021719/Source2/curve), and given the lack of archival detection, we suggest this source to be the afterglow of GRB 241001A.
This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 101004719.

GCN Circular #37670
J.P. Osborne (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), K.L. Page (U. Leicester) 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 241001A, collecting 3.3 ks of Photon Counting (PC) mode data between T0+6.4 ks and T0+13.6 ks.
Four uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below:
Source 1:

  RA (J2000.0):  20.4336  =  01:21:44.05
  Dec (J2000.0): -43.4616  =  -43:27:41.9
  Error: 7.8 arcsec (radius, 90% conf.)
  Count-rate: (2.09 [+1.25, -0.92])e-3 ct s^-1	 
  Distance: 261 arcsec from SVOM/ECLAIRs position.
  Flux: (6.1 [+3.7, -2.7])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:

  RA (J2000.0):  20.5530  =  01:22:12.71
  Dec (J2000.0): -43.4752  =  -43:28:30.6
  Error: 3.4 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0167 [+0.0029, -0.0027] ct s^-1   
  Distance: 397 arcsec from SVOM/ECLAIRs position.
  Flux: (7.1 +/- 1.2)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 3:

  RA (J2000.0):  20.4876  =  01:21:57.02
  Dec (J2000.0): -43.3786  =  -43:22:43.1
  Error: 6.2 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (4.9 [+1.9, -1.5])e-3 ct s^-1   
  Distance: 583 arcsec from SVOM/ECLAIRs position.
  Flux: (4.6 [+1.8, -1.4])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 5:

  RA (J2000.0):  20.5067  =  01:22:1.60
  Dec (J2000.0): -43.4924  =  -43:29:32.5
  Error: 7.6 arcsec (radius, 90% conf.)
  Count-rate: (2.06 [+1.24, -0.91])e-3 ct s^-1	 
  Distance: 262 arcsec from SVOM/ECLAIRs position.
  Flux: (9.9 [+6.0, -4.4])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

We note that Source 2 is spatially consistent with the optical afterglow candidate reported in Izzo & Malesani, GCN #37667, adding credence to this being the real afterglow.
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/00021719.
This circular is an official product of the Swift-XRT team.

GCN Circular #37673
L. Izzo (INAF-OACn and DARK/NBI) and D. B. Malesani (DAWN/NBI and Radboud Univ.) report:
Upon further analysis, we have found that the coordinates of the GRB 241001A afterglow candidate reported in GCN #37667 were incorrect by approximately 7 arcminutes along the Declination axis.
The corrected coordinates for the afterglow candidate (J2000.0) are:
```
RA = 01:22:12.71
Dec = -43:28:31.8
```
We apologize for any confusion or issues this error may have caused
GCN Circular #37677
J. T. Palmerio (CEA), B. Schneider (MIT), D. B. Malesani (DAWN/NBI and Radb= oud Univ.), A. Saccardi (GEPI/Obs. de Paris), L. Izzo (INAF-OACn & DARK/NBI= ), P. D=E2=80=99Avanzo (INAF-OAB), S. D. Vergani (GEPI/Obs. de Paris), A. d= e Ugarte Postigo (LAM/OCA, CNRS) and A. J. Levan (Radboud Univ.) report o= n behalf of the Stargate collaboration:
We observed the optical counterpart of the SVOM/ECLAIRs GRB 241001A (Schann= e et al., GCN 37655) using the ESO VLT UT3 (Melipal) equipped with the X-sh= ooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, a= nd consist of 4 exposures of 1200 s each. The observations mid-time is 07:1= 1:17 UT on 2024 October 02 (~14 hours after the SVOM timeTb).
In a 60 s image taken with the acquisition camera, we detect the optical af= terglow (Izzo & Malesani, GCN 37673), for which we measure an AB magnitude = r =3D 22.3 (calibrated against nearby stars from the Legacy Survey DR10 cat= alog).
In a preliminary reduction of the spectra, we detect a continuum over the e= ntire wavelength range. From the detection of multiple absorption features,= which we interpret as due to Fe II and Mg II, we infer a common redshift o= f z =3D 0.5727. We also detect bright emission lines ([O II] and [O III] do= ublets, and Hbeta) at a consistent redshift of z =3D 0.5730, which we inter= pret as being due to the GRB host galaxy. We conclude that GRB 241001A is a= t z =3D 0.573.
We acknowledge expert support from the ESO staff in Paranal, in particular = Diego Parraguez and Michael Marsset.
GCN Circular #37678
A.A. Breeveld (UCL-MSSL) and R. Caputo (GSFC) report on behalf of the Swift= /UVOT team:
The Swift/UVOT began settled observations of the field of GRB 241001A 6534 s after the SVOM/ECLAIRS trigger (Dagoneau et al. GCN 37655). A fading source consistent with the optical afterglow position given by Izzo et al. (GCN 37673), and the XRT candidate (Osborne et al. GCN 37670) is found in the U band images. Preliminary magnitudes using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:
```
Filter     T_start(s)   T_stop(s)      Exp(s)         Mag

u          6533.5       8438.8         1875           20.20 =C2=B1 0.15
u         12310.1      13655.8         2649           20.91 =C2=B10.24
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) =3D 0.013 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #37679
D. Turpin (CEA-Saclay/Irfu), H. Lau Jun Xian (Tsinghua Univ.), O. Pyshna (Caltech), S. Agayeva, Z. Vidadi (Shamakhy Obs.), S. Antier (OCA), S. Karpov (FZU), M. Coughlin (UMN), C. Andrade (UMN), I. Tosta e Melo (UniCT-DFA), P. Hello, N. Leroy (IJCLAB), P-A Duverne (APC), T. Pradier (Unistra/IPHC), N. Guessoum (AUS), A. Klotz (IRAP/OMP), J.-G. Ducoin (CPPM), M. Freeberg (KNC) on behalf of the GRANDMA and Kilonova-Catcher collaborations:
We observed the field of GRB 241001A (Dagoneau et al., GCN 37655) with GRANDMA and its citizen science project Kilonova-catcher (KNC). Our observations were performed with the TAROT-Reunion (TRE), TAROT-Chile (TCH) and iTelescope T72 telescopes starting from TGRB+42.3 min to TGRB+12h.
In the stacked TRE images, we detect a faint optical counterpart consistent in position with the Swift XRT source 2 (Osborne et al., GCN 37670) and with the optical afterglow candidate reported by Izzo et al., GCN 37667, Palmerio et al., GCN 37677. We do not detect the optical transient in our following observation epochs showing a clear fading since our first TRE epoch and the LCO and VLT observation (Izzo et al., GCN 37667; Palmerio et al., GCN 37677).
All our observations and upper limits (5 sigma C.L.) can be found here:
```
+------------+-----------+-------------+----------------+
| Tmid-T0	|Filter  | Mag (AB)    |  Instrument 	|
+============+===========+=============+================+
| 48.75 min  |  Clear    |18.9 +/- 0.2 | TRE          	|
| 3.18 h     |  Clear    |20.0 (U.L.)  | TRE           	|
| 11.43 h    |  Rc       |21.1 (U.L.)  | iT72          	|
| 13.45 h    |  Clear    |20.3 (U.L.)  | TCH           	|
+------------+-----------+-----------+------------------+
```
Images obtained in Johnson Cousin filters were calibrated using the Gaia DR3 Synphot catalog, images taken by TAROT were calibrated using the SkyMapper DR4 Catalog.
All the data have been reduced by a single data processing pipeline STDPIPE (Karpov et al., 2022). We use the Skyportal application (skyportal.io) to monitor our observational campaign.
GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).
GCN Circular #37685
M. Ferro, R. Brivio, P. D=E2=80=99Avanzo, Y.-D. Hu, S. Covino, and D. Fugaz= za (INAF-OAB) report on behalf of the REM team: We observed the field of GRB 241001A, detected by SVOM/ECLAIRs (Dagoneau et= al. GCN 37655), with the REM 60cm robotic telescope located at the ESO obs= ervatory of La Silla (Chile). The observations were carried in the g, r, i,= z, J, H bands, starting on 2024 October 02 at 05:31:19 UT (i.e. 12.38 hour= s after the SVOM trigger), and lasting for about 1.5 hours. From preliminary photometry we do not detect any optical/NIR counterpart at= the afterglow position (Osborne et al. GCN 37670; Izzo & Malesani, GCN 376= 73; Breeveld et al. GCN 37678; Turpin et al. GCN 37679) down to the followi= ng 3sigma magnitude upper limits: H > 18.3 (Vega; calibrated against the 2MASS catalogue)
r > 19.3 (AB; calibrated against the SkyMapper catalogue)
at a mid-time of t - t0 =3D 13.13 hours after the trigger.
GCN Circular #37695
SVOM/VT commissioning team: Y. L. Qiu, L. P. Xin, H. L. Li, C. Wu, X. H. Ha= n, W. J. Xie, H. B. Cai, Y. Xu, Y. J. Xiao, P. P. Zhang, J. S. Deng, L. La= n, X. M. Lu, R. S. Zhang (NAOC), J. Zhang, L. J. Dan, G. Y. Zou, C. J. Wan= g, Y. F. Du, C. Huang (XIOPM)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (I= HEP), St=C3=A9phane Basa (LAM), Jean-Luc Atteia (IRAP), Arnaud Claret (CEA)= , Zi-Gao Dai (USTC), Fr=C3=A9d=C3=A9ric Daigne (IAP), Jin-Song Deng (NAOC),= Andrea Goldwurm (APC), Diego G=C3=B6tz (CEA), Xu-Hui Han (NAOC), Cyril Lac= haud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Par= is), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Bing Zhang (UNLV= )
report on behalf of the SVOM team:
During the commissioning phase of SVOM mission, we observed the GRB 241001A= , detected by SVOM/ECLAIRs (Dagoneau et al. GCN 37655) with SVOM/VT telesco= pe in ToO mode. The observation started at 2024-10-02T11:21:03 UT, approxim= ately 18 hours after the burst, with a total exposure time of 3860 seconds.= The VT telescope conducted observations simultaneously in two channels: VT= _B (400nm-650nm) and VT_R (650nm-1000nm).
After stacking the images for both bands separately, the optical counterpar= t (as reported by Osborne et al. GCN 37670; Izzo & Malesani, GCN 37673; Bre= eveld et al. GCN 37678; Turpin et al. GCN 37679) was detected with magnitud= es of VT_B =3D 23.54+/-0.20 mag and VT_R =3D 23.52+/-0.23 mag in the AB mag= nitude system.=20
The SpaceVariable Objects Monitor (SVOM) is a China-France joint mission le= d by the Chinese National Space Administration (CNSA, China), National Cent= er for Space Studies (CNES, France) and the Chinese Academy of Sciences (CA= S, China), which is dedicated to observing gamma-ray bursts and other trans= ient phenomena in the energetic universe. VT was jointly developed by Xi'an= Institute of Optics and Precision Mechanics (XIOPM), CAS and National astr= onomical observatories (NAOC),CAS.
GCN Circular #37713
Alexis Coleiro, Floriane Cangemi (APC), Tais Maiolino, F. Piron (LUPM), Jin= gwei Wang (IAP), Maria-Grazia Bernardini (INAF), Jean-Luc Atteia, Laurent B= ouchet, Sebastien Guillot, Juliette Alaux, Hui Yang (IRAP), Nicolas Dagonea= u, St=C3=A9phane Schanne, Fr=C3=A9d=C3=A9ric Chateau, Herv=C3=A9 Le Provost= (CEA), Wenjin Xie (NAOC), Karine Mercier, Marie-Claire Charmeau, Stefano C= repaldi (CNES)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (I= HEP), St=C3=A9phane Basa (LAM), Olivier Godet (IRAP), Arnaud Claret (CEA), = Zi-Gao Dai (USTC), Fr=C3=A9d=C3=A9ric Daigne (IAP), Jin-Song Deng (NAOC), A= ndrea Goldwurm (APC), Diego G=C3=B6tz (CEA), Xu-Hui Han (NAOC), Cyril Lacha= ud (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:
Considering the excellent followup for GRB 241001A detected and localized b= y SVOM/ECLAIRs (GCN 37655), and the redshift measured by the VLT (z =3D 0.5= 73, GCN 37677), we provide here a spectral analysis showing that this trans= ient qualifies as an X-Ray Flash (XRF).=20
The following properties have been measured in the 5 - 20 keV energy range = (no count is detected beyond 20 keV).
```
T90 [s] =3D 11.7 (-4.4 / +2.0)
Fluence [erg cm-2] =3D  7e-8
Spectral parameters for a broken power law fit (red. chisqr =3D 0.86):=20
gamma_1 =3D -1.7 (-0.6 / +1.3)=20
E_break [keV] =3D 9.96 (-2.60 / +2.77)
gamma_2 =3D -5.4 (-2.2 / +1.9)
```
With these parameters, the fluence ratio [2-30]/[30-400] keV =E2=89=88 340,= well above 1, the empirical limit used to define X-Ray Flashes (Sakamoto e= t al. 2005).
Moreover:
```
- A pure PL fit is rejected with high significance (red. chisqr =3D 2.9), i=
ndicating that the spectrum requires a cutoff at a few keV.
- A BB fit is fully acceptable (and preferred over the broken PL, with red.=
 chisqr =3D 0.56), the best fit temperature is kT=3D1.8 +/- 0.2 keV
```
ECLAIRs being in the commissioning phase, the quoted spectral results shall= be taken with some caution. In any case, the XRF classification is certain.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission l= ed by the Chinese National Space Administration (CNSA), French Space Agency= (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to o= bserving gamma-ray bursts and other transient phenomena in the energetic un= iverse. ECLAIRs was developed jointly by APC, CEA, CNES, and IRAP.
GCN Circular #37725
J.P. Osborne (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), K.L. Page (U. Leicester) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has conducted further observations of the field of the SVOM/ECLAIRs-detected burst GRB 241001A. The observations now extend from T0+6.5 ks to T0+456.2 ks.
Of the sources previously reported, "Source 2" is fading with >3-sigma significance, and is therefore likely the GRB afterglow. As previously noted, this source is spatially consistent with the optical afterglow reported in GCNs 37673, 37677, 37678, 37679 and 37695.
Using 3254 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 20.55276, -43.47506 which is equivalent to:
```
RA (J2000): 01h 22m 12.66s
Dec(J2000): -43d 28' 30.2"
```
with an uncertainty of 3.4 arcsec (radius, 90% confidence). This position is 6.6 arcmin from the SVOM/ECLAIRs position. The source is fading with alpha >0.3.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021719. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021719.
This circular is an official product of the Swift-XRT team.
GCN Circular #37809
D. Turpin (CEA), M. Xuan, J. W. Hu, H. W. Pan, W. Yuan (NAOC, CAS), C. Plasse, D. Adrien (CEA/irfu), J. Guan, C. K. Li, Y . Chen, S. M. Jia, W. W. Cui, D. W. Han, W. Li, C. Z. Liu, F . J. Lu, L. M. Song, J. Wang, J. J. Xu, J. Zhang, S. N. Zhang, H. S. Zhao, X. F . Zhao (IHEP , CAS), Y . Liu, C. C. Jin, C. Zhang, Z. X. Ling, J. Wang, L. P . Xin (NAOC,CAS), E. Kuulkers, A. Santovincenzo (ESA), P . O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA) on behalf of the SVOM and Einstein Probe teams
We performed a follow-up observation of GRB 241001A (Dagoneau et al., GCN 37655) with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation started at 2024-10-10T02:43:51 (T-TGRB ~ 0.52 day) for about 6 ks of exposure in total.
We detected an uncatalogued x-ray source at a position consistent with the Swift/XRT afterglow (Osborne et al., GCN 37725). Compared to the first Swift/XRT epoch (Osborne et al., GCN 37670) the source had faded by about an order of magnitude to F_X = 5.1e-14 +/- 1.2e-14 erg.cm-2.s-1 in the 0.3-10 keV energy band.
We thus confirm that the Swift/XRT source #2 is the afterglow of GRB 241001A.
The above observation was made with the EP-FXT instrument. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.
GCN Circular #37857
J. K. Leung (U. Toronto/HUJI), G. E. Anderson (Curtin University), L. Rhodes (TSI/McGill), S. Chastain (UNM), A. Gulati (U. Sydney), A. J. van der Horst (GWU) on behalf of the PanRadio GRB collaboration
We observed the field of GRB 241001A (Dagoneau et al., GCN 37655) at 5.5 and 9 GHz with the Australia Telescope Compact Array (ATCA) on 10 October 2024 from 16:00 to 20:00 UT and 19 October 2024 from 11:00 to 13:00 UT. The telescope pointing centre was placed at the location of the optical afterglow candidate (Izzo et al., GCN 37667, GCN 37673).
In our preliminary analysis, we marginally detect a ~0.04 mJy source at the phase centre at 5.5 GHz in the first observation. The source had faded below detection thresholds by the time of the second observation.
We thank the CSIRO Space and Astronomy staff for supporting these observations. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.
GCN Circular #37867
B. P. Gompertz (U. Birmingham), A. J. Levan (Radboud Univ. and Warwick Univ= .), D. B. Malesani (DAWN/NBI and Radboud Univ.), B. Schneider (MIT), L. Izz= o (INAF-OACn & DARK/NBI), T. Laskar (University of Utah) and A. Martin-Carr= illo (UCD) report for a larger collaboration:
We obtained spectroscopic observations of the optical counterpart (Izzo & M= alesani., GCNs 37667 and 37673; Breeveld et al., GCN 37678; Turpin et al., GCN 37679; SVOM/VT commissioning team, GCN 37695) to the SVOM/ECLAIRs-detec= ted GRB 241001A (SVOM/ECLAIRs Commissioning Team; GCN 37655) at redshift z = = 0.57 (Palmerio et al., GCN 37677) with the James Webb Space Telescope (= JWST). Observations were carried out using the NIRSpec instrument on 2024-1= 0-23, 21.5 days after trigger (13.7 days in the GRB rest frame). The total integration time was 1.7 hours with the clear prism in the wavelength range 0.5 - 5.5 =C2=B5m.
The trace reveals a blue spectrum showing multiple broad absorption/emissio= n features, similar to those observed in broad-lined type-Ic SNe commonly a= ssociated with long-duration GRBs. In particular, the spectrum matches well the one of GRB980425 / SN1998bw at 14 - 21 rest-frame days after collapse (Patat et al. 2001, Apj, 555, 900).
We acknowledge excellent support from Diane Karakla and Amber Armstrong (both STScI) in preparing these observations.

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Jochen Greiner, last update: 25-Oct-2024 [Disclaimer]