GRB240402B

This page lists all entries on GRB240402B in GRBweb

Summary IPN GCN 36017 GCN 36018 GCN 36025 GCN 36028 GCN 36030 GCN 36034 GCN 36114 GCN 36253 GCN 36385

Summary table
Variable Value Source
T0 8:47:48.797 UTC GCN_circulars,Konus-Wind Det
ra 245.4375° IPN
decl 25.8000° IPN
pos_error 2.50e-02° IPN
redshift 1.5510 GCN_circulars,Konus-Wind Det
GBM_located False
mjd 60402.366537002315 GCN_circulars,Konus-Wind Det
IPN table
GRB_name GRB240402B
ra 245.4375°
decl 25.8000°
pos_error 2.50e-02°
redshift 1.5510
GCN 36017 table
GRB_name GRB240402B
GCN_number 36017
Detection_method Konus-Wind Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 36017 SUBJECT: GRB 240402B: GECAM-C detection DATE: 24/04/03 17:01:02 GMT FROM: Kai Wang-Chen Xue, Shao-Lin Xiong, Chao Zheng, Yanqiu Zhang, and Chengkui Li, report on behalf of the GECAM team: GECAM-C observed a long burst, GRB 240402B at 2024-04-02T08:47:46 UTC (denoted as T0), which has been detected by LEIA (GCN 36016) and Konus-Wind. According to the observation data of GECAM-C, this burst mainly consists of two peaks with a duration (T90) of 6.55 +/- 0.52 sec (15-350 keV). The GECAM-C localization is consistent with the LEIA localization (GCN 36016) within the error. The time-averaged spectrum of GECAM-C data from T0-7.0 to T0+7.0 s could be adequately fit by a cut-off power-law with photon index alpha of -0.62 (-0.14, +0.13), and peak energy Ep of 66 (-3, +3) keV. The corresponding burst fluence is 7.69 (-0.24, +0.25) * 10^-7 erg/cm^2 in 15-350 keV. We note that these results are preliminary and refined analysis will be reported later. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN 36018 table
GRB_name GRB240402B
GCN_number 36018
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 36018 SUBJECT: GRB 240402B: GWAC-F50A optical upper limit DATE: 24/04/03 22:56:22 GMT FROM: Liping Xin at NAOC, SVOM L.P.Xin(NAOC), Y.G.Yang(HNU), C.WU(NAOC), Y.L.Qiu(NAOC), J.Wang(GXU/NAOC), L.H.Li(NAOC), C.Wu(NAOC), E.W.Liang(GXU), X.H.Han (NAOC), X.M.Lu(NAOC), R.S.Zhang(NAOC), Y.Xu(NAOC), Y.J.Xiao(NAOC), P.P.Zhang(NAOC), L.Lan(NAOC), J.Y.Wei(NAOC) on behalf of the SVOM/GWAC team: We began to observe X-ray transient LXT 240402A (Xu et all., GCN 36106) detected by LEIA, which was also detected by GECAME-C as GRB 240402B (Xue et al., GCN 36107), with GWAC-F50A telescope, at Xinglong station, China, at 19:22:13 (UT), 03. April. 2024, about 34.57 hours after the burst. The weather was not good. After stacking 5*200 seconds, no any new sources were detected in our stacked image down to a limit magnitude of 18.0 mag in R band comparing to several nearby USNO B1.0 stars. We acknowledge the excellent support from observation assistant Yangtong Zheng.
GCN 36025 table
GRB_name GRB240402B
GCN_number 36025
Detection_method Optical
ra 245.4510°
decl 25.7631°
Circular_text TITLE: GCN CIRCULAR NUMBER: 36025 SUBJECT: GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate DATE: 24/04/04 14:40:14 GMT FROM: Andrew Levan at Radboud University A.J. Levan (Radboud), D.B. Malesani (DAWN/NBI & Radboud), P.G. Jonker (Radboud), N.R. Tanvir (Leicester), M. E. Ravasio (Radboud), A. Martin-Carrillo (UCD), G. Pugliese (Amsterdam), S. Campana (INAF/Brera), D. Xu (NAOC/CAS) report on behalf of the Stargate collaboration: We obtained observations of FXT/GRB 240402B (Xu et al., GCN 36016; Xue et al., GCN 36017) with the FORS2 imager on the VLT UT1 (Antu). Observations began at 06:44 UT on 4 April 2024, approximately 1.9 days after the high-energy detection. We obtained a total of 1400 s of observations in the R band. Within the 10” error box of the X-ray transient located by Einstein Probe follow-up observations (Jia et al., GCN 36022), we identify a new source not present in archival images retrieved via the Legacy Survey. This source lies at RA = 16:21:48.247 Dec = +25:45:47.34 We suggest this is the optical afterglow of FXT/GRB240402B. Photometry is complicated by the presence of a nearby star just 1” away (a confirmed star, given a Gaia measured proper motion), but the magnitude of the transient at the time of the observations was approximately r ~ 22 calibrated to Pan-STARRS. The offset from the nearby galaxy CGCG 138-001 (z = 0.047) is approximately 200 kpc in projection, at the higher end of those expected for ejected compact object mergers. We thank the staff at the VLT for the rapid execution of these observations, in particular Julia Seidel.
GCN 36028 table
GRB_name GRB240402B
GCN_number 36028
Detection_method Konus-Wind Det
t_trigger 8:47:48.797 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 36028 SUBJECT: Konus-Wind detection of LXT 240402A/GRB 240402B DATE: 24/04/04 15:59:11 GMT FROM: Anna Ridnaia at Ioffe Institute A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 240402B (GECAM-C detection: Xue et al., GCN 36017) associated with the LEIA fast X-ray transient LXT 240402A (Xu et al., GCN 36016) triggered Konus-Wind at T0=31668.797 s UT (08:47:48.797). The burst light curve shows a multipeaked structure which starts at ~T0-0.2 s and has a total duration of ~5.1 s. The emission is seen up to ~3 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB240402_T31668/ As observed by Konus-Wind, the burst had a fluence of 7.56(-0.43,+0.50)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+2.704 s, of 5.07(-0.66,+0.68)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 4 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.71(-0.17,+0.19), the high energy photon index beta = -3.58(-1.30,+0.44), the peak energy Ep = 86(-4,+5) keV (chi2 = 57/68 dof). This spectrum is nearly-well fitted by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.78(-0.15,+0.16) and Ep = 88(-4,+4) keV (chi2 = 61/69 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN 36030 table
GRB_name GRB240402B
GCN_number 36030
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 36030 SUBJECT: LXT 240402A/GRB 240402B: Glowbug gamma-ray detection DATE: 24/04/04 19:13:46 GMT FROM: C.C. Cheung at Naval Research Lab C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of LXT 240402A/GRB 240402B, which was also detected by LEIA (GCN 36016), GECAM-C (GCN 36017), and Konus/Wind (GCN 36028). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2024-04-02 08:47:45.240 with a duration of 4.1 s and a total significance of about 18.3 sigma. The light curve comprises two primary peaks at ~T0+0.5s and ~T0+3s. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS. The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006 Distribution Statement A: Approved for public release. Distribution is unlimited.
GCN 36034 table
GRB_name GRB240402B
GCN_number 36034
Detection_method Other
redshift 0.0470
Circular_text TITLE: GCN CIRCULAR NUMBER: 36034 SUBJECT: LXT 240402A/GRB 240402B: GECAM-C refined analysis DATE: 24/04/05 01:59:44 GMT FROM: Chenwei Wang at IHEP Wangchen Xue, Shaolin Xiong, Chenwei Wang, Chengkui Li, Shuxu Yi on behalf of GECAM team Following our initial analysis reported in GCN 36017, here we analyzed the Amati relation for this burst. We find that, if this burst had a redshift of z~0.047 (Levan et al.; GCN 36025, Xu et al., GCN 36016), it falls in the short burst region, supporting the compact object merger origin as also evident by the large offset from the galaxy (Levan et al., GCN 36025). The small spectral lag compared to its luminosity also indicates the compact object merger origin. The associated gravitational wave would likely have been observed if LVK was observing at the time of this burst. The gravitational wave of such kind of GRB with small redshift would be potentially observed in O4b of LVK. With the probable compact object merger origin of this GRB, follow-up observations are encouraged.
GCN 36114 table
GRB_name GRB240402B
GCN_number 36114
Detection_method Swift Other
ra 245.4490°
Circular_text TITLE: GCN CIRCULAR NUMBER: 36114 SUBJECT: LXT 240402A/GRB 240402B: Swift follow-up observations DATE: 24/04/15 13:21:33 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group A. Martin-Carrillo (UCD), S. Campana (INAF/Brera), D. B. Malesani (DAWN/NBI & Radboud Univ.), A. J. Levan (Radboud Univ.), G. Pugliese (Amsterdam), D. Xu (NAOC/CAS), N. R. Tanvir (Leicester), P. G. Jonker (Radboud Univ.), A. Rossi (INAF-OAS), P. O’Brien (Leicester) report on behalf of the Stargate collaboration: Following up the LEIA trigger LXT 240402A (Xu et al., GCN 36016) associated with the Konus-Wind GRB 240402B (Ridnaia et al., GCN 3628) and the detection of its X-ray counterpart (Jia et al., GCN 36022) a series of Swift follow-up observations (PI Xu, ID: 203030 and PI Martin-Carrillo, ID: 20382) were performed between April 7 and April 14, with a total exposure time of 8 ks. Combining all the data, a source is well detected with a count rate of 1.9 (+0.7, -0.6) x 10^-3 count s^-1 at the coordinates (J2000): RA: 16:21:47.75 (245.4490); Dec: +25:45:45.9’ (25.7627); Error: 5.8” (90% confidence). Using the spectral parameters of the EP-FXT detection (Jia et al., GCN 36022), this corresponds to an observed flux of 7.7*10^-14 erg cm^-2 s^-1. Assuming a mid-point for the Swift observations of 8.5 days after the LEIA trigger, and using a single power-law decay, the X-ray flux decays with an approximate index -1.2, typical for a GRB afterglow. The source centroid lies within 1.5" from the optical counterpart reported by Levan et al. (GCN 36025) and Yang et al. (GCN 36027). The reduced localisation error strengthens its association with the proposed optical counterpart. We thank the Neil Gehrels Swift Observatory team for making these ToO observations possible.
GCN 36253 table
GRB_name GRB240402B
GCN_number 36253
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 36253 SUBJECT: LXT240402A/GRB240402B: Chandra X-ray detection DATE: 24/04/23 12:55:40 GMT FROM: muskan.yadav@students.uniroma2.eu M. Yadav, E. Troja, Y. -H. Yang, and R. L. Becerra (U. Rome) report: Following the detection of the fast X-ray transient LXT 240402A (Xu et al., GCN 36016) associated with GRB 240402B (Wang et al., GCN 36017), we performed observations of the field with the Chandra X-ray Observatory starting at UT 00:48 on April 15, 2024 for a total exposure of 16 ks. An X-ray source is detected with high significance at the location of the optical counterpart (Yang at al., GCN 36094). Using the spectral parameters of the EP-FXT detection (Jia et al., GCN 36022) we derive an X-ray flux of 8*10^-14 erg s^-1 cm^-2 (0.5-10 keV), consistent with the Swift/XRT observations (Martin-Carrillo et al., GCN 36114). We thank Pat Slane and the CXO staff for quickly arranging and executing the observations.
GCN 36385 table
GRB_name GRB240402B
GCN_number 36385
Detection_method Konus-Wind Det
redshift 1.5510
Circular_text TITLE: GCN CIRCULAR NUMBER: 36385 SUBJECT: LXT 240402A / GRB 240402B: VLT X-shooter redshift of host DATE: 24/05/03 15:23:10 GMT FROM: nrt3@le.ac.uk N. R. Tanvir (U. Leicester), J. Palmerio (GEPI/Obs. de Paris), D. B. Malesani (DAWN/NBI & Radboud U.), A. J. Levan (Radboud U.), A. Saccardi (GEPI/Obs. de Paris), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud U.), K. Wiersema (U. Hertfordshire), Y. Julakanti (U. Leicester) report on behalf of the Stargate collaboration: We obtained observations of the location of the X-ray transient LXT 240402A (Xu et al., GCN 36016; Jia et al., GCN 36022; Levan et al., GCN 36025), coincident with GRB 240402B detected by GECAM-C (Xue et al., GCN 36017) and Konus-Wind (Ridnaia et al., GCN 36028), using the X-shooter spectrograph at the VLT. Observations began at 04:04 (UT) on 03 May 2024, approximately 31 days after the trigger. The spectrum covers a wavelength range roughly 0.31 to 2.1 mum, with a total integration time of 4800 s. A weak continuum is seen throughout the spectrum, and we clearly detect emission lines of [O II], H-beta, [O III], H-alpha, and tentatively Ly-alpha, at a common redshift of z = 1.551. We propose that these lines are from the host of the transient. Based on the gamma-ray fluence seen by Konus-Wind in the 20 keV - 10 MeV band (Ridnaia et al., GCN 36028) we conclude an isotropic-equivalent energy release in gamma-rays of 4.7x10^52 erg. This places it very close to the mean Amati relationship (Amati et al. 2006 MNRAS 372 233), and thus is consistent with a long-GRB origin. We thank ESO support staff Zahed Wahhaj and Francisco Caceres for undertaking these observations.