GRB 241127A
GCN Circular 38354
Subject
GRB 241127A: Swift detection of a burst with an optical counterpart
Date
2024-11-27T21:59:40Z (6 months ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
C. Salvaggio (INAF-OAB), R. Brivio (INAF-OAB), S. Dichiara (PSU),
M. Ferro (INAF-OAB), R. Gupta (NASA GSFC), A. Y. Lien (U Tampa),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
A. Tohuvavohu (Caltech) and M. A. Williams (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 21:43:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 241127A (trigger=1270788). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 327.922, -56.685 which is
RA(J2000) = 21h 51m 41s
Dec(J2000) = -56d 41' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 10 sec. The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 21:44:22.8 UT, 66.6 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 327.88355, -56.66459 which
is equivalent to:
RA(J2000) = 21h 51m 32.05s
Dec(J2000) = -56d 39' 52.5"
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This
location is 105 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper. We cannot determine whether the source
is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.68 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 6.1
(+6.36/-4.83) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 2.12e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 484 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 21:51:32.32 = 327.88467
DEC(J2000) = -56:39:55.1 = -56.66531
with a 90%-confidence error radius of about 0.61 arc sec. This position is 2.1
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.14 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.034.
Burst Advocate for this burst is C. Salvaggio (chiara.salvaggio AT inaf.it).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)
GCN Circular 38359
Subject
GRB 241127A: LCOGT (40-cm) optical counterpart detection
Date
2024-11-28T04:18:13Z (6 months ago)
From
Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es>
Via
Web form
I. Ortega-Casas, B. Armas-Chinea, F. Dobrindt, P. Escudero-Coca, G. Fernández-Rodríguez, Á. García Lozano, A. Huertas Ferrer, C. Méndez-Lapido, M. Torreiro Martínez, G. Villa (all ULL), S.R. Berlanas (IAC and ULL), and I. Pérez-Fournon (IAC and ULL)
We report on optical follow-up observations of GRB 241127A, detected by Swift BAT, XRT, and UVOT (Salvaglio et al., GCN circular 38354) and by MASTER (Buckley et al., GCN circular 38352 and Francile et al., GCN circular 38358).
We observed the field of GRB 241127A with the two Las Cumbres Observatory Global telescope network (LCOGT) Planewave Delta Rho 350 telescopes, equipped with QHY600 CMOS detectors, located at the LCOGT node at the Cerro Tololo Inter-American Observatory (Chile) in the SDSS r', i', and g' filters, with 600 sec exposures in each of the filters. We detect the optical counterpart at a position consistent with the Swift UVOT (Salvaglio et al., GCN circular 38354) and MASTER (Buckley et al., GCN circular 38352 and Francile et al., GCN circular 38358) detections.
We measure the following magnitudes, calibrated using stars from the catalog of Gaia DR3 synthetic photometry generated from the Gaia BP/RP mean spectra (Gaia collaboration 2022) and without corrections for Milky Way extinction:
r' = 19.42 +/- 0.08, on 2024-11-28 00:58:30 UT, 3.25 hours after the Swift trigger
i' = 19.27 +/- 0.15, on 2024-11-28 01:04:49 UT, 3.36 hours after the Swift trigger
g' = 19.70 +/- 0.07, on 2024-11-28 01:10:03 UT, 3.45 hours after the Swift trigger
In the Legacy Surveys DR10 catalog there is a faint galaxy close to the position of the GRB optical counterpart at RA, Dec (J2000, deg) = 327.8851, -56.6653 and with magnitudes g = 25.08, r = 24.70, i = 24.38, and z = 23.57, that is the likely GRB host galaxy.
These results are based on observations made with the Las Cumbres Observatory’s education network
telescopes that were upgraded through generous support from the Gordon and Betty Moore Foundation
and are part of a course on Astrophysical Techniques of the Master in Astrophysics of the Universidad de La Laguna, Tenerife, Spain (LCOGT observing programme IAC2024B-010, ULL-ASTRO-MASTER).
GCN Circular 38362
Subject
GRB 241127A: Enhanced Swift-XRT position
Date
2024-11-28T07:55:25Z (6 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2379 s of XRT Photon Counting mode data and 9 UVOT
images for GRB 241127A, 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 = 327.88543, -56.66544 which is equivalent
to:
RA (J2000): 21h 51m 32.50s
Dec (J2000): -56d 39' 55.6"
with an uncertainty of 2.1 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 38363
Subject
GRB 241127A: SVOM/GRM observation
Date
2024-11-28T09:08:34Z (6 months ago)
From
zhengchao_astro@foxmail.com
Via
Web form
SVOM/GRM team: Chao Zheng, 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, 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 (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, SVOM/GRM detected GRB 241127A at 2024-11-27T21:43:16.230 UT (T0), which was also observed by Swift/BAT (C. Salvaggio, et al., GCN 38354).
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 duration of about 3 s.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb241127A.png
This burst is located at about 75.6 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), the 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/GRM point of contact for this burst is: Chao Zheng (IHEP)(zhengchao97@ihep.ac.cn)
GCN Circular 38364
Subject
GRB 241127A: Swift-XRT refined Analysis
Date
2024-11-28T11:07:18Z (6 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
A. Melandri (INAF-OAR), S. Dichiara (PSU), J.A. Kennea (PSU), D.N.
Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester),
T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and P.A. Evans report on
behalf of the Swift-XRT team:
We have analysed 5.0 ks of XRT data for GRB 241127A, from 443 s to 27.9
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=0.66 (+0.05, -0.06).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.97 (+0.18, -0.17). The
best-fitting absorption column is 8.0 (+4.5, -3.9) x 10^20 cm^-2, in
excess of the Galactic value of 2.7 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 3.4 x 10^-11 (4.0 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 8.0 (+4.5, -3.9) x 10^20 cm^-2
Galactic foreground: 2.7 x 10^20 cm^-2
Excess significance: 2.2 sigma
Photon index: 1.97 (+0.18, -0.17)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01270788.
This circular is an official product of the Swift-XRT team.
GCN Circular 38365
Subject
GRB 241127A: Swift/UVOT Detection
Date
2024-11-28T13:21:45Z (6 months ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
Via
email
A. A. Breeveld (UCL-MSSL) and C. Salvaggio (INAF-OAB) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 241127A 484 s after the BAT trigger (Salvaggio et al., GCN Circ. 38354).
The optical counterpart seen in the UVOT at the position given in that circular, and also reported by Ortega-Cass et al., (GCN Circ. 38359) and MASTER (Buckley et al., GCN circular 38352 and Francile et al., GCN circular 38358) is detected in all the filters used for the initial UVOT exposures and is fading.
Preliminary magnitudes 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 484 634 147 17.04 ± 0.03
white 16459 16862 393 19.81 +/1 0.09
b 15547 16453 885 20.3 ± 0.3
u 21787 22629 821 19.1 ± 0.1
v 10002 10870 847 19.7 ± 0.2
uvw1 20881 21780 886 19.5 ± 0.3
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.034 in the direction of the burst (Schlegel et al. 1998).
GCN Circular 38366
Subject
GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
Date
2024-11-28T16:24:29Z (6 months ago)
From
Thomas Hussenot-Desenonges at IJCLab <thomas.hussenot@ijclab.in2p3.fr>
Via
Web form
T. Hussenot-Desenonges (IJCLAB), D. Akl (AUS), M. Coughlin (UMN), M. Molham (NRIAG), S. Agayeva (Shamakhy Obs.),
S. Antier (OCA), C. Andrade (UMN), S. Karpov (FZU), I. Tosta e Melo (UniCT-DFA), P. Hello (IJCLAB), P-A Duverne (APC), T. Pradier (Unistra/IPHC), N. Guessoum (AUS),
M. Masek (FZU), A. Klotz (IRAP), D. Turpin (CEA-Saclay/Irfu), M. Freeberg (KNC), on behalf of the GRANDMA and Kilonova-Catcher collaborations:
We observed the field of GRB 241127A, detected by SWIFT (GCN 38354) and SVOM (GCN 38363) with the GRANDMA network and its citizen science project Kilonova-catcher (KNC).
Our observations were performed with the TAROT-TCH, FRAM-Auger and the KNC-CHI-1, 60cm telescopes.
We detect the afterglow already observed by Swift/XRT and UVOT (GCN 38354, 38362, 38364, 38365), MASTER (GCN 38353, 38358) and LCOGT (GCN 38359) and obtain the following magnitudes:
| Tstart (UTC) | Telescope | Exposure | Filter | Magnitude |
| 2024-11-28T00:33:05 | FRAM-Auger | 20x120s | R | 18.78 +- 0.20 (Vega)|
| 2024-11-28T00:50:45 | TAROT-TCH | 4x180s | R | 19.14 +- 0.17 (Vega)|
| 2024-11-28T01:16:26 | KNC-CHI-1 | 2x120s | r' | 19.4 +- 0.1 (AB) |
| 2024-11-28T01:20:52 | KNC-CHI-1 | 2x120s | g' | 19.74 +- 0.09 (AB) |
All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). TCH and KNC images were calibrated using the SkyMapper DR4 catalogue, the FRAM-Auger image used Gaia DR3 Synphot.
The data are not corrected from Galaxy extinction.
Our magnitudes are consistent with those reported by LCOGT in GCN 38359.
We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023)
A report of the observations of GRANDMA for this source can be seen at:
https://skyportal-icare.ijclab.in2p3.fr/public/sources/GRB241127
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 38384
Subject
GRB 241127A: PRIME near-infrared detection
Date
2024-11-29T19:31:33Z (6 months ago)
From
Joe Durbak at UMD <gcn.joedurbak@gmail.com>
Via
Web form
J. Durbak (UMD), E. Troja (U Rome), O. Guiffreda (UMD), A. S. Kutyrev (NASA/GSFC), S. B. Cenko (NASA/GSFC)
Following the Swift BAT detection (GCN 38354), we observed the transient field in J and H filters with PRIME ~23 hours after Swift detection.
At the position of the optical counterpart reported by Swift UVOT (GCN 38354), we detect an uncatalogued source in J-band. Using nearby VISTA Hemispherical Survey (VHS) for preliminary calibration we derive the following magnitude and limit, not corrected for Galactic extinction:
| Filter | Mag(AB) |
|--------|--------------|
| J | 20.5 +/- 0.1 |
| H | > 20.1 |
PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO) (Kutyrev et al. 2023, Yama et al. 2023, Durbak et al. 2024).
We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations.
GCN Circular 38386
Subject
GRB 241127A: Swift-BAT refined analysis
Date
2024-11-30T02:05:21Z (6 months ago)
From
Amy <yarleen@gmail.com>
Via
email
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm
(NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. J. Moss (GSFC), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), C. Salvaggio
(INAF-OAB), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-50 to T+242 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 241127A (trigger #1270788)
(Salvaggio et al., GCN Circ. 38354). The BAT ground-calculated position is
RA, Dec = 327.911, -56.652 deg which is
RA(J2000) = 21h 51m 38.5s
Dec(J2000) = -56d 39' 08.1"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 100%.
The mask-weighted light curve shows some weak emission that starts at ~T-21
s, followed by the main pulse that starts at ~T-1 s, peaks at ~T+1 s, and
ends at ~T+9 s. T90 (15-350 keV) is 26.02 +- 3.63 sec (estimated error
including systematics).
The time-averaged spectrum from T-20.83 to T+9.13 sec is best fit by a
power law with an exponential cutoff. This fit gives a photon index 1.10
+- 1.01, and Epeak of 19.0 +- 12.56 keV (chi squared 52.96 for 56 d.o.f.).
For this model the total fluence in the 15-150 keV band is 6.5 +- 0.8 x
10^-07 erg/cm2 and the 1-sec peak flux measured from T+0.09 sec in the
15-150 keV band is 2.3 +- 0.2 ph/cm2/sec. A fit to a simple power law
gives a photon index of 2.65 +- 0.21 (chi squared 60.15 for 57 d.o.f.).
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/1270788