GRB 241115A

The Fermi GBM team reports the detection of a likely LONG GRB

At 13:18:24 UT on 15 Nov 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 241115A (trigger 753369509.732778 / 241115554).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 85.2, Dec = 2.7 (J2000 degrees, equivalent to J2000 05h 40m, 2d 42'), with a statistical uncertainty of 6.0 degrees.

The angle from the Fermi LAT boresight is 43.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241115554/quicklook/glg_skymap_all_bn241115554.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241115554/quicklook/glg_healpix_all_bn241115554.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241115554/quicklook/glg_lc_medres34_bn241115554.gif

M. A. Williams (PSU), J. J. DeLaunay (PSU), S. Dichiara (PSU),
R. Gupta (NASA GSFC), K. L. Page (U Leicester) and D. M. Palmer (LANL)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 13:18:25 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 241115A (trigger=1267921).  Swift slewed immediately to the burst.
The BAT on-board calculated location is 
RA, Dec 86.765, -0.662 which is 
   RA(J2000) = 05h 47m 04s
   Dec(J2000) = -00d 39' 44"
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 5 sec.  The peak count rate
was ~7600 counts/sec (15-350 keV), at ~1 sec after the trigger.

The XRT began observing the field at 13:20:14.5 UT, 109.5 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 86.77049, -0.67381 which
is equivalent to:
   RA(J2000)  = 05h 47m 04.92s
   Dec(J2000) = -00d 40' 25.7"
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This
location is 46 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. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (3.32 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 9.4
(+6.11/-4.63) x 10^21 cm^-2 (90% confidence).

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 113 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
1.028.

Burst Advocate for this burst is M. A. Williams (mjw6837 AT psu.edu).
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/)

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) started inspect of the Fermi GRB 241115A ( Fermi GBM team, GCN 38234
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 ) errorbox  2796 sec after notice time and 2828 sec after trigger time at 2024-11-15 14:05:33 UT, with upper limit up to  14.0 mag. The observations began at zenith distance = 83 deg. The sun  altitude  is -44.1 deg. 

The galactic latitude b = -14 deg., longitude l = 203 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2671089

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

    2832 | 2024-11-15 14:05:33 |        MASTER-Tunka | (05h 47m 14.08s , -00d 46m 37.1s) |   C |     5 | 14.0 |        
    2871 | 2024-11-15 14:06:12 |        MASTER-Tunka | (05h 47m 14.46s , -00d 48m 32.9s) |   C |     5 | 13.8 |        
    2888 | 2024-11-15 14:06:30 |        MASTER-Tunka | (05h 47m 20.52s , -00d 48m 31.2s) |   C |     5 | 13.9 |        
    3335 | 2024-11-15 14:13:59 |        MASTER-Tunka | (05h 47m 20.28s , -00d 46m 37.9s) |   C |     1 | 13.7 |        
    3348 | 2024-11-15 14:14:12 |        MASTER-Tunka | (05h 47m 14.99s , -00d 47m 15.0s) |   C |     1 | 13.3 |        
Filter C is a clear (unfiltred) band. 


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

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 241115A ( M. A. Williams et al., GCN 38235
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 ) errorbox  2802 sec after notice time and 2828 sec after trigger time at 2024-11-15 14:05:33 UT, with upper limit up to  16.4 mag. The observations began at zenith distance = 83 deg. The sun  altitude  is -44.1 deg. 

The galactic latitude b = -14 deg., longitude l = 206 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2671057

We obtain a following upper limits.  

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

    2831 |        MASTER-Tunka |   C |     5 | 14.0 |        
    2871 |        MASTER-Tunka |   C |     5 | 13.8 |        
    2888 |        MASTER-Tunka |   C |     5 | 13.9 |        
    3335 |        MASTER-Tunka |   C |     1 | 13.7 |        
    3348 |        MASTER-Tunka |   C |     1 | 13.3 |        
    5552 |        MASTER-Tunka |   C |    60 | 16.4 |  Coadd 
Filter C is a clear (unfiltred) band. 


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

R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:

We observed the Swift GRB 241115A field (Williams et al., GCN 38235
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 )  with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on November 15, from 21:52 to 22:24 UT (corresponding to 8.57 to 9.10 hours after the GRB trigger time) with the sdss r and i filters.

We performed a series of 3x300s exposures in i- and r-bands.  We do not detect a source within the Swift XRT error region in either band.

The following 5-sigma upper limits are calculated using the PanSTARRS catalog as reference:

r > 21.5
i > 21.2

These magnitudes are not corrected for galactic extinction.

C. de Barra (University College Dublin), M. Dafčíková (Masaryk U.), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 13:18:24.73 UT on 15 November 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 241115A (trigger 753369509/241115554).
which was also detected by Swift BAT (M. A. Williams et al. 2024, GCN 38235
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 ).
The Fermi GBM on-ground location is consistent with the Swift BAT position.

The angle from the Fermi LAT boresight is 46 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 3.1 s (50-300 keV). The time-averaged spectrum
from T0-3.4 to T0+5.8 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.7 +/- 0.1 and the cutoff energy,
parameterized as Epeak, is 90 +/- 7 keV.

The event fluence (10-1000 keV) in this time interval is
(1.57 +/- 0.08)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.32 s in the 10-1000 keV band is 7.7 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 80 +/- 9 keV, alpha = -0.6 +/- 0.2 and beta = -2.7 +/- 0.4.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"

Guowang Du, Brajesh Kumar, Weikang Lin, Yehao Cheng, Yaosong Yu, Yu Pan, Xingzhu Zou, Xinlei Chen, Jinghua Zhang, Yuanpei Yang, Yuan Fang, Xiangkun Liu, Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team:

The field of GRB 241115A (Williams et al., GCN 38235
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 )was observed with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory starting from 15:54:07 UT 2024-11-15 (~2.6 hr after the trigger). Multiple frames with 180s and 50s exposures in uvgr bands were taken. No new source is detected in our stacked images, consistent to Lipunov et al., (GCN 38237
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 ) and Strausbaugh & Cucchiara (GCN 38246
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 ). The 3-sigma upper limits are listed below.

Start_Time(UT)      Band  Exp(s) Lim-mag(AB)
2024-11-15T15:54:07  u    180*3   >20.35
2024-11-15T16:04:30  v    180*3   >20.65
2024-11-15T15:54:07  g     50*9   >21.06
2024-11-15T16:04:31  r     50*9   >21.38
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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. 
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R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR),
D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P.
Osborne (U. Leicester), 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
Swift-BAT-detected burst GRB 241115A, collecting 11.3 ks of Photon
Counting (PC) mode data between T0+92 s and T0+102.8 ks. 

An uncatalogued X-ray source is detected consistent with being within
296 arcsec of the Swift-BAT position and is above the RASS 3-sigma
upper limit at this position and fading with >3-sigma significance, and
is therefore likely the GRB afterglow. Using 2620 s of PC mode data and
5 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 = 86.77097, -0.67462 which is equivalent to:

RA (J2000): 05h 47m 05.03s
Dec(J2000): -00d 40' 28.6"

with an uncertainty of 2.2 arcsec (radius, 90% confidence). This
position is 50 arcsec from the Swift-BAT position. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.13 (+/-0.07).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.0 (+/-0.4). The
best-fitting absorption column is  1.7 (+0.6, -0.5) x 10^22 cm^-2, in
excess of the Galactic value of 3.3 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 5.9 x 10^-11 (1.2 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.7 (+0.6, -0.5) x 10^22 cm^-2
Galactic foreground: 3.3 x 10^21 cm^-2
Excess significance: 4.5 sigma
Photon index:	     2.0 (+/-0.4)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01267921.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/01267921.

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

J. Durbak (UMD), O. Guiffreda (UMD), A. S. Kutyrev (NASA/GSFC), E. Troja (U Rome), S. B. Cenko (NASA/GSFC)

Following the Swift BAT (GCN 38235
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 ) and Fermi GBM (GCN 38234
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 ) detection, we observed the transient field in H-filter with PRIME ~3.5 days after Swift and Fermi detection.

At the counterpart positions reported by Swift XRT (GCN 38235
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 ) and Swift UVOT (GCN 38256
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 ), we detect no uncatalogued sources in H-band. Using nearby 2MASS stars for preliminary calibration we derive a limiting magnitude of <20.0 AB, not corrected for Galactic extinction

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.

N. Cannady (GSFC/UMBC), A. Yoshida, T. Sakamoto, S. Sugita, 
Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), 
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu,
T. Tamura (Kanagawa U), M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The GRB 241115A (Fermi GBM Final Real-time Localization: Fermi GBM team,
GCN Circ 38234
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 ; Swift detection of a burst: Williams et al., GCN Circ 38235
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 ;
Fermi GBM Observation: de Barra et al., GCN Circ 38247
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 ) triggered the CALET 
Gamma-ray Burst Monitor (CGBM) at 13:18:24.988 UTC on 15 November 2024
(https://cgbm.calet.jp/cgbm_trigger/flight/1415711919/index.html).
The burst signal was seen by all CGBM detectors.  Because of a problem with the ground 
alert processing script, the GCN notice was not distributed automatically for this event.

The burst light curve shows a single pulse that starts at T-0.6 sec, peaks at T+0.1 sec, 
and ends at T+1.6 sec. The T90 and T50 durations measured by the SGM data are 2.0 
+/- 0.3 sec and 1.1 +/- 0.1 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

https://cgbm.calet.jp/cgbm_trigger/ground/1415711919/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.