GRB 240411B
GCN Circular 36063
Subject
GRB 240411B: Swift detection of a burst
Date
2024-04-11T16:09:02Z (a year ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
T. M. Parsotan (GSFC), S. Dichiara (PSU),
R. A. J. Eyles-Ferris (U Leicester), C. Gronwall (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester),
B. Sbarufatti (INAF-OAB), M. H. Siegel (PSU) and M. A. Williams (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 15:32:54 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 240411B (trigger=1221183). Swift slewed immediately to the burst.
No further BAT information is available at this time due to a
telemetry gap. Further information will be available after the
next telemetry pass over a ground station.
The XRT began observing the field at approximately 15:35:54 UT, around 180
seconds after the BAT trigger. Using promptly downlinked data we find an
uncatalogued X-ray source with an enhanced position: RA, Dec 231.54236,
-2.14609 which is equivalent to:
RA(J2000) = 15h 26m 10.17s
Dec(J2000) = -02d 08' 45.9"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). 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 consistent with the Galactic value of 1.11
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White
filter starting 190 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 none of the XRT error circle. 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 0.138.
Burst Advocate for this burst is T. M. Parsotan (parsotat AT umbc.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/)
GCN Circular 36064
Subject
GRB 240411B: LCO optical afterglow detection
Date
2024-04-11T18:43:10Z (a year ago)
From
luca.izzo@inaf.it
Via
Web form
L. Izzo (INAF-OACn & DARK/NBI), D. B. Malesani (DAWN/NBI and Radboud Univ.), M. Della Valle and R. Martone (INAF-OACn) report:
We observed the field of GRB 240411B (Parsotan et al., GCN 36063) with the Sinistro instrument mounted on the 1-m telescope of the LCO network, located at Siding Spring Observatory, Australia. Observations started on April 11 at 17:02:54 UT (1.5 hours after the GRB trigger). We obtained a series of 3x180 s images in the r filter.
In the stacked image, we detect a new source within the XRT position, at the coordinates:
RA(J2000) = 15:26:10.17
Dec(J2000) = -02:08:46.8
We measure a preliminary magnitude of r = 21.66 +- 0.22 (AB), calibrated against nearby stars from the Pan-STARRS catalog.
This source is not visible in the Pan-STARRS catalog and is thus very likely the optical afterglow of GRB 240411B.
This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 730890.
GCN Circular 36065
Subject
GRB 240411B: Enhanced Swift-XRT position
Date
2024-04-11T19:09:04Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 373 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 240411B, 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 = 231.54213, -2.14640 which is equivalent
to:
RA (J2000): 15h 26m 10.11s
Dec (J2000): -02d 08' 47.0"
with an uncertainty of 2.6 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 36067
Subject
GRB 240411B: OHP/T193 optical observations
Date
2024-04-12T05:38:40Z (a year ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Via
Web form
B. Schneider (MIT), C. Adami (LAM/Pytheas/AMU), E. Le Floc’h (CEA Paris-Saclay), A. Saccardi (GEPI/Obs. de Paris) report on behalf of a larger collaboration:
We observed the field of the GRB 240411B (Parsotan et al., GCN 36063; Goad et al., GCN 36065) and its afterglow candidate (Izzo et al., GCN 36064) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. A total of 10 exposures (8x600s + 2x720s) were obtained in the r-band at 00:44:01.5 UT on 2024-04-12 (~9.2h after the trigger). In the combined frame, we detect a source consistent with the optical afterglow reported by Izzo et al. (GCN 36064).
The preliminary magnitude derived for that source is
r = 23.1 +/- 0.3 mag (AB)
The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitude is not corrected for Galactic extinction.
We acknowledge the excellent support from Observatoire de Haute-Provence and in particular Jean-Pierre Troncin for the MISTRAL observations.
GCN Circular 36069
Subject
GRB 240411B: 1.3m DFOT Optical observations
Date
2024-04-12T10:52:24Z (a year ago)
From
Amit Kumar Ror at ARIES <mitturor77894@gmail.com>
Via
email
Amit K. Ror, Anshika Gupta, Rahul Gupta, Amar Aryan, Saurabh, and Shashi B.
Pandey (ARIES) report:
We observed the field of GRB 240411B detected by Swift (Parsotan et al.,
2024 GCN 36063) with the 1.3m Devasthal Fast Optical Telescope (DFOT),
located at the Devasthal Observatory of the Aryabhatta Research Institute
of Observational Sciences (ARIES), India. The observations were started on
2024-04-11 at 19:06:28 UT, i.e., ~ 3.56 hours after the BAT trigger. We
have taken multiple frames with an exposure time of 300 s in the R filter.
We stacked the images after the alignment. We clearly detected an optical
afterglow (Izzo et al., 2024, GCN 36064; Schneider et al., 2024, GCN 36067)
in our final stacked image within the error box of enhanced Swift-XRT
observation (Goad et al., 2024, GCN 36065). The estimated preliminary
magnitude is as follows:
Date Start_UT T_start-T0 (hours) Filter Exp time (s) Limiting magnitude
=======================================================
2024-04-11 19:06:28 UT 3.56 R 300*15 22.34 +/- 0.11
The detection of the afterglow is consistent with the observations of Izzo
et al. 2024, GCN 36064, and Schneider et al. 2024, GCN 36067.
The given magnitude value is not corrected for the Galactic and host
extinctions in the direction of the GRB afterglow. Photometric calibration
is performed using the standard stars from the USNO-B1.0 catalog. This
circular may be cited.
GCN Circular 36071
Subject
GRB 240411B: Swift-XRT refined Analysis
Date
2024-04-12T16:36:29Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
P. D'Avanzo (INAF-OAB), J. D. Gropp (PSU), S. Dichiara (PSU), J.A.
Kennea (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U.
Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) and
P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 3.9 ks of XRT data for GRB 240411B, from 160 s to 74.6
ks after the BAT trigger. The data comprise 10 s in Windowed Timing
(WT) mode (taken while Swift was slewing), with the remainder in Photon
Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.66 (+0.12, -0.11).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.13 (+0.38, -0.20). The
best-fitting absorption column is consistent with the Galactic value
of 1.1 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 3.2 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.1 (+/-1.0) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.13 (+0.38, -0.20)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01221183.
This circular is an official product of the Swift-XRT team.
GCN Circular 36072
Subject
GRB 240411B: Swift-BAT refined analysis
Date
2024-04-12T17:35:46Z (a year ago)
From
Mike Moss at NASA GSFC <mikejmoss3@gmail.com>
Via
Web form
A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
C. B. Markwardt (GSFC), M. J. Moss (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC),
T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 240411B (trigger #1221183)
(Parsotan, et al., GCN Circ. 36063). The BAT ground-calculated position is
RA, Dec = 231.562, -2.172 deg which is
RA(J2000) = 15h 26m 14.8s
Dec(J2000) = -02d 10' 20.9"
with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 53%.
The mask-weighted light curve shows two spikes separated by an interval of ~15 seconds.
The estimated T90 (15-350 keV) is 33.26 +- 1.49 sec (estimated error including systematics).
The time-averaged spectrum from T-0.37 to T+33.92 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.69 +- 0.41. The fluence in the 15-150 keV band is 4.9 +- 1.2 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+32.87 sec in the 15-150 keV band
is 0.9 +- 0.3 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/1221183
GCN Circular 36074
Subject
GRB 240411B: HiPERCAM/GTC observation
Date
2024-04-12T19:07:20Z (a year ago)
From
Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>
Via
email
A. de Ugarte Postigo (CNRS, OCA, LAM), N. R. Tanvir (U. Leicester), J. F. Agui Fernandez (CAHA), A. Martin-Carrillo (UCD), C. C. Thoene (ASU-CAS), L. Izzo (INAF-OACn & DARK/NBI), J. P. U. Fynbo (DAWN/NBI), G. Lombardi (GRANTECAN), S. Geier (GRANTECAN) report:
We observed the field of GRB 240411B (Parsotan et al. GCN 36063) with HiPERCAM on the 10.4m GTC, at the Roque de Los Muchachos Observatory (Spain). We simultaneously obtained 20x60s exposure in each of the u, g, r, i, and z filters. The transparency was bad due to strong calima and the seeing was also poor. The afterglow (Izzo et al. 36064; Goad et al. GCN 36065; Schneider et al. GCN 36067; Ror et al. GCN 36069) is well detected in g, r, i and z, but not in u-band, where the limit is shallow. Observations had a mean time of 0.4256 days after the burst. We measure an r-band magnitude (AB) of r = 23.21+/- 0.08 mag as compared with field star magnitudes from the SDSS.
GCN Circular 36077
Subject
GRB 240411B: Kinder observations with Lulin observatory
Date
2024-04-13T03:50:18Z (a year ago)
From
Amar Aryan <amararyan941@gmail.com>
Via
Web form
A. Aryan, T.-W. Chen, C.-S. Lin, W.-J. Hou, A. Sankar.K, Y.-C. Pan (all NCUIA), S. Yang (HNAS), M.-H. Lee, C.-H. Lai, H.-Y. Hsiao, C.-C. Ngeow, H.-C. Lin, J.-K. Guo (all NCUIA), S. Srivastav (Oxford), M. Fulton, T. Moore, C. Angus, and A. Aamer (all QUB) report:
We observed the field of GRB 240411B (Parsotan et al., GCN 36063; Goad et al., GCN 36065; D'Avanzo et al., GCN 36071; Lien et al., GCN 36072) using the Lulin One-meter Telescope (LOT) at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen et al., AstroNote 2021-92). The optical afterglow candidate of GRB 240411B was identified (Izzo et al., GCN 36064) and followed with several instruments (Schneider et al., GCN 36067; Ror et al., GCN 36069).
The first LOT epoch of observations started at 16:45 UT on 11 of April 2024. We followed standard IRAF (Tody D., 1993, ASPC, 52, 173) procedure to reduce the images. Further, PSF photometry was performed using DAOPHOT II (Stetson P. B., 1987, PASP, 99, 191) software. The details of the observations and the preliminary magnitudes (in the AB system) of the afterglow are as follows:
Telescope | Filter | MJD | t-t0 | Exposure | Magnitude | avg. Seeing | med. Airmass
LOT | r | 60411.698 | 1.25 hrs | 300 sec * 1 | 20.92 +/- 0.12 | 1".16 | 1.17
LOT | i | 60411.715 | 1.65 hrs | 300 sec * 1 | 20.28 +/- 0.15 | 1".0 | 1.13
The presented magnitudes are calibrated using the nearby stars from the PanSTARRS catalog and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.14 mag in the direction of the burst (Schlafly & Finkbeiner 2011).
GCN Circular 36078
Subject
GRB 240411B: CrAO/ZTSh optical observations
Date
2024-04-13T07:42:11Z (a year ago)
From
Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>
Via
legacy email
N. Pankov (HSE,IKI), V. Rumyantsev (CrAO), A. Pozanenko (IKI), S. Belkin
(IKI) report on behalf of IKI GRB FuN:
We observed the field of GRB 240411B (Parsotan et al., GCN 36063; Goad et
al., GCN 36065; D'Avanzo et al., GCN 36071; Lien et al., GCN 36072) with
ZTSh 2.6m telescope of CrAO observatory starting on 2024-04-11 (UT)
21:18:47. We detect optical afterglow (Izzo et al. GCN 36064; Schneider et
al. GCN 36067; Ror et al. GCN 36069; Ugarte Postigo et al. GCN 36074; Aryan
et al. GCN 36077).
Preliminary photometry of the afterglow in a combined image is following
Date UT start t-T0 Filter Exp. OT err UL(3sigma)
(mid, days) (s)
2024-04-11 21:18:47 0.283257 R 60*120 22.40 0.25 22.8
The photometry is based on several nearby USNO-B1.0 (R2) stars
USNO-B1.0
GCN Circular 36179
Subject
GRB 240411B: Swift/UVOT Detection
Date
2024-04-19T12:32:47Z (a year ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
Via
email
S. J. LaPorte (PSU) and T. M. Parsotan (GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 240411B
190 s after the BAT trigger (Parsotan et al., GCN Circ. 36063). A source
consistent
with the XRT position (Goad et al., GCN Circ. 36065) and the reported
optical transient (Izzo et al. GCN 36064; Schneider et
al. GCN 36067; Ror et al. GCN 36069; Ugarte Postigo et al. GCN 36074; Aryan
et al. GCN 36077; Pankov et al. GCN 36078) is detected in the initial UVOT
exposures.
Preliminary detections and 3-sigma upper limits 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
b 6480 6680 196 >19.84
v 7096 7295 196 >18.58
uvw2 6891 7091 196 >19.45
white 6685 6885 196 >20.54
white 198 348 147 20.08+-0.27
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.022 in the direction of the burst
(Schlegel et al. 1998).