GRB 241128A

R. Brivio (INAF-OAB), M. Ferro (INAF-OAB), C. Gronwall (PSU),
R. Gupta (NASA GSFC), A. Y. Lien (U Tampa), K. L. Page (U Leicester),
D. M. Palmer (LANL), C. Salvaggio (INAF-OAB) and
T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 16:14:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 241128A (trigger=1270999).  Swift slewed immediately to the burst.
The BAT on-board calculated location is 
RA, Dec 273.724, +33.435 which is 
  RA(J2000) = 18h 14m 54s
  Dec(J2000) = +33d 26' 07"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  Although a telemetry gap prevented
the download of a BAT lightcurve, the trigger duration of 4 s
indicates that this is a long burst.

The XRT began observing the field at 16:16:32.2 UT, 118.0 seconds after
the BAT trigger. No source was detected in the 2.5-s promptly available
image. We are waiting for the full dataset to detect and localise the
XRT counterpart.

There are no prompt UVOT data available at this time.

Although this source has not been confirmed during the short XRT observation
(truncated by entrance into the SAA) or by the non-availability of the
BAT lightcurve, the strength of peak (8.4 sigma) in the BAT image
indicates that this is an astrophysical source.

Burst Advocate for this burst is R. Brivio (riccardo.brivio 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/)

K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:

Immediately following the BAT trigger on GRB 241128A, Swift entered the
South Atlantic Anomaly, during which time no XRT data were taken. The
field of the GRB became visible to the XRT at 17:16 UT, 3.9 ks after the
trigger, at which point the XRT afterglow of the burst was detected at a
position of RA, Dec = 273.72454, 33.43853 which is equivalent to:

RA (J2000): 18:14:53.89
Dec(J2000): +33:26:18.9

with an uncertainty of 3.5 arcsec (radius, 90% confidence).

This circular is an official product of the Swift-XRT team.

Y.-D. Hu (INAF-OAB), V. Casanova, E. Fernandez-Garcia, A. J. Castro-Tirado, S.-Y. Wu, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy (IAA-CSIC) and G. Garcia-Segura (UNAM), on behalf of a larger collaboration, report:

Following the detection of GRB 241128A by Swift (Brivio et al. GCN 38367
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 ), we triggered the 1.5m OSN telescope in Granada (Spain) starting on Nov 28, 18:19 UT (~2.1 hrs post burst) in R & I-bands. An uncatalogued object is detected within the XRT error circle (Page et al. GCNC 38368) with R=19.3+-0.1 mag, at coordinates RA(J2000) = 18:14:53.55, DEC(J2000) = +33:26:20.32, which we proposed as the GRB 241128A optical afterglow.

Spectroscopic observations are encouraged.

We thank the staff at OSN for their excellent support.

L. Izzo (INAF-OACn and DARK/NBI), and D. B. Malesani (DAWN/NBI and Radboud Univ.) report:

We observed the field of GRB 241128A (Brivio et al., GCN #38367
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 ) with the Sinistro instrument mounted on the 1-m telescope of the LCO network, located at the Teide Observatory, Spain. Observations started on 2024 November 28 at 19:04 UT (2.83 hr after the GRB trigger). We obtained a series of 3x300 s images in the SDSS-r filter.

The afterglow reported by Hu et al. (GCN #38371
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 ; see also Page et al., GCN #38368
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 ) is well detected in our images. We measure a preliminary magnitude of r = 19.24 +/- 0.07 mag (AB), calibrated against nearby stars from the Pan-STARRS catalog.

This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 101004719.

B. Gompertz (Birmingham), D. B. Malesani (DAWN/NBI and Radboud Univ.), L. Izzo (INAF/OACN, DARK/NBI), J. H. Terwel (NOT and TCD) report on behalf of a larger collaboration:

We observed the field of GRB 241128A (Brivio et al., GCN 38367
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 ; Page, GCN 38368
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 ) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations were carried out at large airmass and under a poor seeing of 2.5". A total of 3x300 s and 5x200 s were secured in the SDSS r and z bands, respectively.

From a preliminary reduction of the data, the optical afterglow (Hu et al., GCN 38371
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 ; Izzo & Malesani, GCN 38372
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 ) is well detected in our images. We measure

r = 19.52 +- 0.03 AB  on Nov 28.80 UT (2.95 hr after the GRB);
z = 19.03 +- 0.05 AB  on Nov 28.81 UT (3.25 hr after the GRB).

Both magnitudes are calibrated against nearby objects from the Pan-STARRS catalog.

We note a discrepancy in the r-band magnitude compared to the nearly simultaneous measurement by Izzo & Malesani (GCN 38372
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 ), which we are unable to account for at the present time.

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1910 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 241128A, 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 = 273.72356, +33.43915 which is equivalent
to:

RA (J2000): 18h 14m 53.65s
Dec (J2000): +33d 26' 20.9"

with an uncertainty of 3.0 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.

J.A. Kennea (PSU), D.N. Burrows (PSU), M. A. Williams (PSU), A.P.
Beardmore (U. Leicester), J.P. Osborne (U. Leicester), T. Sbarrato
(INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB) and P.A.
Evans report on behalf of the Swift-XRT team:

We have analysed 6.2 ks of XRT data for GRB 241128A, from 3.9 ks to
28.3 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=0.51 (+/-0.15).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.07 (+0.31, -0.25). The
best-fitting absorption column is  8.9 (+7.5, -2.9) x 10^20 cm^-2,
consistent with the Galactic value of 6.0 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 3.2 x 10^-11 (4.0 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     8.9 (+7.5, -2.9) x 10^20 cm^-2
Galactic foreground: 6.0 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.07 (+0.31, -0.25)

If the light curve continues to decay with a power-law decay index of
0.51, the count rate at T+24 hours will be 0.017 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.6 x
10^-13 (6.9 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01270999.

This circular is an official product of the Swift-XRT team.

V.Lipunov, E.Gorbovskoy, N.Tiurina,  P.Balanutsa, , D.Vlasenko, I.Panchenko,
A.Kuznetsov,  G.Antipov,  A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin,
V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez  (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) 

MASTER-Tunka robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the Swift GRB 241128A ( R. Brivio et al., GCN 38367
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 ) errorbox  65606 sec after notice time and 65649 sec after trigger time at 2024-11-29 10:28:43 UT, with upper limit up to  19.3 mag. Observations started at twilight.  The observations began at zenith distance = 43 deg. The sun  altitude  is -12.6 deg. 

The galactic latitude b = 21 deg., longitude l = 61 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2687409

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   65694 |        MASTER-Tunka |   C |    90 | 19.1 |        
   65798 |        MASTER-Tunka |   C |    90 | 19.2 |        
   65887 |        MASTER-Tunka |   C |    60 | 19.3 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

D. Akl (AUS), E. de Bruin  (UMN), C. Andrade (UMN), M. Tanasan (NARIT), N. Kochiashvili (AbAO), T. Hussenot-Desenonges (IJCLAB), M. Coughlin (UMN), M. Molham (NRIAG), S. Agayeva (Shamakhy Obs.), 
S. Antier (OCA), S. Karpov (FZU), D. Turpin (CEA-Saclay/Irfu), 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), M. Boer, S. Gervasoni, C. Limonta (OCA), E. Broens, F. Kugel (KNC), on behalf of the GRANDMA and Kilonova-Catcher collaborations:

We observed the field of GRB 241128A (Brivio et al., GCN 38367
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 ) detected by Swift-BAT with GRANDMA and its citizen science project Kilonova-catcher (KNC). Our observations were performed with the FRAM-CTA-N, TAROT-TCA, KNC T400, and KNC-T-BRO telescopes starting from TGRB+108 min. 

We clearly detect the optical afterglow within the Swift-XRT uncertainty region (Beardmore et al., GCN 38374
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 ) and obtain the following magnitudes and 5-sigma upperlimits:
+---------------------+-------------+--------+----------------+------------+
| T-mid(UTC)          | Exposure(s) | Filter | Mag (AB)       | Instrument |
+=====================+=============+========+================+============+
| 2024-11-28T18:02:48 | 27x60       | Clear  | 19.50 +/- 0.07 | KNC        | 
| 2024-11-28T18:11:15 | 7x180       | Clear  | 19.78 +/- 0.22 | KNC        | 
| 2024-11-28T18:38:26 | 11x180      | Clear  | 19.67 +/- 0.19 | KNC        |
| 2024-11-28T19:31:58 | 18x120      | R      | 17.84 (U.L.)   | FRAM-CTA-N |
| 2024-11-28T19:40:56 | 3x180       | Clear  | 17.53 (U.L.)   | TAROT-TCA  |
+---------------------+-------------+--------+----------------+------------+

Our detection is consistent with the optical afterglow detected and reported by Hu et al., GCN 38371
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 .
Further, our magnitudes are consistent with those reported by LCO (Izzo and Malesani, GCN 38372
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 ) and NOT (Gompertz et al., GCN 38373
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 ).  

All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained in Johnson Cousin filters were calibrated using the Gaia DR3 Synphot catalog, while images taken with a clear filter were calibrated using the Gaia eDR3 Catalog.

We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). 

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/).

N. Pankov (HSE, IKI),  A. Pozanenko (IKI), E. Klunko (ISTP),  A. Volnova (IKI) report on behalf of GRB IKI FuN:

We observed  the field of GRB 241128A (Brivio et al., GCN 38367
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 ; Page, GCN 38368
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 )  with AZT-33IK telescope of Mondy observatory  in  R-filter on 2024-11-29 starting (UT) 10:48:37. We detect the afterglow (Hu et al., GCN 38371
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 ; Izzo and Malesani, GCN 38372
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 ;  Gompertz et al., GCN 38373
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 ; Akl  et al., GCN 38382
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 ). 

Preliminary photometry  of the afterglow is the following

Date       UT start  t-T0     Exp.   Filter OT     Err.  UL(3sigma)
                   (mid, days)  (s)
2024-11-29 10:48:37  0.79796  15x120 R      19.80  0.10  22.9

The photometry is based on nearby USNO-B1.0 R2 stars. 

T. Parsotan (GSFC), S. D. Barthelmy (GSFC), R. Brivio (INAF-OAB), R. Gupta
(GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B.
Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), D. Sadaula
(GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+899 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 241128A (trigger #1270999)
(Brivio et al., GCN Circ. 38367
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 ).  The BAT ground-calculated position is
RA, Dec = 273.724, 33.492 deg which is
   RA(J2000)  =  18h 14m 53.7s
   Dec(J2000) = +33d 29' 32.9"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 52%.

The mask-weighted light curve shows a multi-pulse structure that starts at
~T0 and ends at ~T+240 s. The main pulse starts at ~T0, peaks at ~T+3 s,
and ends at ~T+10 s. In addition, there is a weak pulse at ~T+220 s. T90
(15-350 keV) is 238.32 +- 15.83 sec (estimated error including systematics).

The time-averaged spectrum from T-0.86 to T+244.08 sec is best fit by a
simple power-law model.  The power law index of the time-averaged spectrum
is 1.54 +- 0.31.  The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-06
erg/cm2. The 1-sec peak photon flux measured from T+2.88 sec in the 15-150
keV band is 1.0 +- 0.2 ph/cm2/sec.  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/1270999

N. Pankov (HSE), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI),
S.  Belkin (HSE, Monash) report on behalf of GRB IKI FuN:

We observed the field of GRB 241128A (Brivio et al., GCN 38367
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 ; Page, GCN
38368
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 ; Parsotan et al., GCN 38387
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 ) with AS-32 telescope of Abastumani
observatory (AbAO) in R-filter on 2024-11-29 starting (UT) 14:47:06. We do
not detect the afterglow (Hu et al., GCN 38371
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 ; Izzo and Malesani, GCN
38372
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 ; Gompertz et al., GCN 38373
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 ; Akl et al., GCN 38382
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 ; Pankov et al.,
GCN 38383
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 ). Preliminary photometry of the field is the following

Date UT start t-T0 Exp. Filter OT Err. UL(3sigma)
(mid, days) (s)
2024-11-29 14:47:06 0.96877 85x60 R n/d n/d 20.2

The photometry is based on nearby USNO-B1.0 R2 stars

S.P.R. Shilling (Lancaster U.) and Brivio (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 241128A
3880 s after the BAT trigger (Brivio et al., GCN Circ. 38367
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 ).
No optical afterglow consistent with the enhanced XRT position
(Beardmore et al., GCN Circ. 38374
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 ) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC          3880         4029          147         >20.0
white             3880         4649          344         >20.6
v                 4860         5059          197         >19.0
b                 4244         4444          197         >19.7
u                 4038         4238          197         >19.2
m2                5065        10054          534         >19.4
w2                4655         4855          197         >19.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.067 in the direction of the burst
(Schlegel et al. 1998).

R. Hamburg (USRA) reports on behalf of the Fermi-GBM Team:

The Swift-BAT detected GRB 241128A on 2024-11-28 at 16:14:34 UTC (Brivio et al. 2024, GCN 38367
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 ). 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 counterparts. 

The GBM Targeted Search [1], a sensitive and coherent search for subthreshold GRB-like signals, was run from +/-30 s around the Swift-BAT trigger time and identified a gamma-ray transient most significantly at 16:14:38 UTC (Fermi MET=754503283), about 4 s after the Swift-BAT trigger time. The transient is approximately 2 s in duration and was identified with the "normal" spectral template (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) with FAR of 1.7e-4 Hz. The Targeted Search localization is consistent with the Swift-BAT location.

[1] Goldstein et al. arXiv:1903.12597
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Thierry Midavaine on behalf of the RAPAS network reports (#3) :
Cédric Latgé, Patrick Martinez [1], Pierre-Michel Bergé, Erik Guthleben, Patrick Martinez [2], Thierry Midavaine [3] observed the Gamma-Ray Burst GRB241128A (R. Brivio et al. GCN 38367
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 , K.L. Page GCN 38368
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 ) using [1][2] ADAGIO N 820mm telescope f=3.1m at Belesta Observatory (IAU A05) equiped with a Moravian C3 CMOS camera, 1200s exposure [1],1500s exposure [2], [3] RC 500mm f=1.414m at Salvia Observatory (I73) equipped with ZWO6200MMPRO CMOS camera, 2400s exposure, [1][2][3] are equiped with RAPAS filters meeting the Gaia G, Gbp, Grp photometric bands. The FITS files are reduced with the Gaia photometric catalog in respective G, Gbp, Grp bands.

The afterglow is detected RA(J2000) = 18h 14m 53.57s ; Dec(J2000) = +33° 26’ 20.4” ; ± 0.5’’ [1][2]
At this location it is not detected, above the upper limit magnitude [3] 

MJD (mid)     Gaia band   mag.(Gaia) RAPAS station
60643.72986   G           20.50 ± 0.5 [1]
60644.77083   G           21.00 ± 0.5 [2]
60647.74270   G+Gbp+Grp  >21.         [3]

RAPAS ( https://proam-gemini.fr/rapas/ ) is a new ProAm collaboration funded by Paris Observatory, delivering to a network of french amateur observatories a set of 3 filters meeting the Gaia spectral bands. This network is dedicated to deliver data in the Gaia photometric system on selected astrophysical alerts by Astro-COLIBRI ( https://astro-colibri.com/ ) or from Gaia alerts.

A. Volnova (IKI), N. Pankov (HSE, IKI), A. Pozanenko (IKI), V. Rumyantsev (CrAO), E. Klunko (ISTP) report on behalf of IKI-GRB-FuN:

We continued observations of the GRB 241128A (Brivio et al., GCN 38367
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 ; Page, GCN 38368
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 ) with 2.6-meter ZTSh telescope of CrAO observatory and 1.5-meter AZT-33IK telescope of Sayan observatory (Mondy). The optical afterglow (Hu et al., GCN 38371
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 ; Izzo and Malesani, GCN 38372
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 ; Gompertz et al., GCN 38373
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 ; Akl  et al., GCN 38382
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 ; Pankov et. al, GCN 38383
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 , GCN 38395
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 ; Shilling & Brivio, GCN 38422
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 ; Midavaine et. al, GCN 38438
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 ) is well detected in the stacked images from ZTSh on both epochs of 2024-11-30 and 2024-12-01. Preliminary photometry is given below:

Date       UT start  t-T0         Exp.   Filter OT     Err.  UL(3sigma) Telescope
                     (mid, days)  (s)
2024-11-30 17:38:32  2.066296    11*120  R      22.03  0.14  23.1       ZTSh
2024-12-01 10:31:12  2.793500    46*120  R      n/d    n/d   21.9       AZT-33IK
2024-12-01 15:19:05  3.000058    48*120  R      23.12  0.11  24.0       ZTSh

The magnitudes were calibrated against nearby PS1 stars (R magnitudes obtained with Lupton transformations) and not corrected for the Galactic extinction. Using the current photometry and our photometry reported previously (Pankov et. al, GCN, 38383) we found that the light curve is well fitted with a simple power-law model with an index of -2.2.

R. Querrard (UVI), P. Gokuldass (ERAU), N. Orange (OrangeWave Innovative Science, LLC), B. Gendre (UVI), D. Morris (NASA), T. Lombardi (Eckerd College), F. George (ERAU), D. Smith (UVI), K. Smith (UVI), C. Watson (UVI) report:

We observed the field of GRB241128A (Brivio et al., GCN 38367
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 ) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 2024-11-29 starting at 22:47:51.703 (T-mid ~ T0 + 30.75 hrs). We performed a series of exposures in an R filter with a total exposure of 1370s. The weather conditions were partly cloudy during the hours of observation with an average airmass of 2.94. 

We do not detect any source within the enhanced XRT position (Beardmore et al. GCN 38374
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 ). This non-detection is consistent with reported detections (Hu et al., GCN 38371
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 ;Izzo et al., GCN 38372
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 ; Gompertz et al., GCN 38373
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 ; Akl et al., GCN 38382
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 ; Pankov et al., GCN 38383
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 ; Midavaine et al., GCN 38438
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 ; and Volnova et al., GCN 38519
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  ) and upper limits  (Lipunov et al., GCN 38380
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 ; Shilling et al., GCN 38422
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 ; Akl et al., GCN 38382
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 ; Pankov et al., GCN 38395
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 ; Midavaine et al., GCN 38438
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 ; and Volnova et al., GCN 38519
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  ). We report the following 3-sigma upper limit:

T_mid                ||Exposure   ||Filter   ||Limit 
T+30.75 hrs          || 1370 s    || R       || > 18.6

The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. 

We acknowledge financial support from NASA EPSCoR award 80NNSC22M0063, NSF PAARE award 2319415, and NASA EPSCoR award 80NSSC24M0112. This message can be cited.