TITLE: GCN CIRCULAR
NUMBER: 36700
SUBJECT: Fermi Gamma-ray Burst Monitor trigger 740474239/240619304 is not a GRB
DATE: 24/06/19 15:20:39 GMT
FROM: rachel.hamburg(a)ijclab.in2p3.fr
R. Hamburg (CNRS/IN2P3/IJCLab) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:
"The Fermi Gamma-ray Burst Monitor (GBM) trigger 740474239/240619304 at 07:17:14.27 UT
on 19 June 2024, tentatively classified as a GRB, is likely not due to a GRB.
This trigger is likely due to noise fluctuations."
View this GCN Circular online at https://gcn.nasa.gov/circulars/36700.
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TITLE: GCN CIRCULAR
NUMBER: 36696
SUBJECT: GRB240615A: 1.3m DFOT optical upper limit
DATE: 24/06/19 06:22:27 GMT
FROM: ANSHIKA GUPTA at ARIES <anshika05180(a)gmail.com>
We observed the field of GRB 240615A detected by Fermi GBM (GCN #36671) and Swift/BAT-GUANO (GCN #36672) and using the 1.3m Devasthal Fast Optical Telescope (DFOT) located at the Devasthal observatory of Aryabhatta Research Institute of observational sciencES (ARIES), Nainital, India. The observation started on 2024-06-16 at 20:07:06 UTC, i.e., ~ 26.25 hours after the trigger. 24 frames of 300 sec exposure were acquired in the R band. We do not detect the optical afterglow (earlier reported in #GCN 36676, #GCN 36680) in the stacked image down to a limiting magnitude of 22.8. The photometric calibration is performed using the standard stars from the USNO-B1.0 catalog.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36696.
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TITLE: GCN CIRCULAR
NUMBER: 36695
SUBJECT: GRB 240619A: BALROG localization (Fermi Trigger 740461416 / GRB 240619155)
DATE: 24/06/19 04:41:44 GMT
FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de>
T. Preis, B. Biltzinger, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
740461416 at 03:43:31 on 19 June 2024 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position is:
RA(2000.0) = 162.2 deg
Decl.(2000.0) = 14.8 deg
The 1 sigma statistical error radius is 3.2 deg.
We estimate an additional systematic error of 2 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB240619155/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB240619155/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB240619155/json
View this GCN Circular online at https://gcn.nasa.gov/circulars/36695.
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TITLE: GCN CIRCULAR
NUMBER: 36693
SUBJECT: EP240617a: BOOTES-6/DPRT optical upper limit
DATE: 24/06/18 21:56:11 GMT
FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct(a)iaa.es>
I. Perez-Garcia, E. Fernandez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland), M. Gritsevich (Univ. of Helsinki), D. R. Xiong (Yunnan Observatories of CAS) and C. J. Perez del Pulgar (UMA, Malaga), on behalf of a larger collaboration, report:
Following the detection of the fast X-ray transient EP240617a (a likely GRB) by the Einstein Probe (Zhou et al. GCNC 36691, Yang et al. GCNC 36692), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) observed the fast X-ray transient location starting on June 18, 19:59 UT (~ 31.6 h after trigger) in different optical bands. No new optical source is detected on the co-added images (clear-filter) within the EP/WXT error box down to 20.4 mag.
We thank the staff at Boyden Observatory for their excellent support.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36693.
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TITLE: GCN CIRCULAR
NUMBER: 36692
SUBJECT: EP240617a is likely a GRB event
DATE: 24/06/18 15:51:31 GMT
FROM: jyang(a)smail.nju.edu.cn
Jun Yang (NJU), Yi-Han Iris Yin (NJU), Binbin Zhang (NJU), Hui Sun (NAOC), Qinyu Wu (NAOC) and Xuefeng Wu (PMO) report on behalf of large collaboration:
Our team has followed up on EP's X-ray flare detection at 2024-06-17T12:19:13 UTC (EP240617a; GCN Circular 36691) and discovered a weak, untriggered gamma-ray transient in the Fermi/GBM data within the occurrence time interval of EP240617a. This transient lasted approximately 100 seconds and its location aligns with that of EP240617a.
Considering the factors that the gamma-ray transient is consistent with EP240617a in terms of event time and location, we are inclined to claim that this is likely a GRB event. A preliminary spectral analysis indicates that its peak energy is below one hundred keV, which suggests its classification as an X-ray rich GRB.
We strongly recommend further follow-up on EP240617a to confirm its physical nature and to detect any afterglows.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36692.
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TITLE: GCN CIRCULAR
NUMBER: 36691
SUBJECT: EP240617a: EP-WXT detection of a fast X-ray transient
DATE: 24/06/18 13:30:06 GMT
FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn>
H. Zhou (PMO, CAS), W. Chen, H. Sun, W. D. Zhang, J. W. Hu, D. Y. Li, Z. X. Ling, Y. Liu, C. Zhang, C. C. Jin, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, M. H. Huang, H. Y. Liu, M. J. Liu, Z. Z. Lv, T. Y. Lian, X. Mao, H. W. Pan, X. Pan, W. X. Wang, Y. L. Wang, Q. Y. Wu, X. P. Xu, Y. F. Xu, H. N. Yang, W. Yuan, M. Zhang, W. D. Zhang, W. J. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), J. Yang, C. Y. Dai (NJU) Y. F. Liang (PMO), Y. Chen, S. M. Jia, S. N. Zhang (IHEP, CAS), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA) on behalf of the Einstein Probe team
We report on the detection of a fast X-ray transient, designated EP240617a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient event started at 2024-06-17T12:19:13 (UTC). The position of the source is R.A. = 285.030 deg, DEC = -22.561 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). The transient event lasts for over 300 seconds before the observation was interrupted due to earth occultation. The lightcurve of the transient exhibits a multi-peak profile. The peak unabsorbed flux is around 1.4(+/-0.1) x 10^-8 erg/s/cm^2 in the 0.5-4 keV band. The average 0.5-4 keV spectrum can be fitted by an absorbed power law with a photon index of 1.1(+/-0.1) (with the column density fixed at the Galactic value of 1.7 x 10^21 cm^-2). The derived average unabsorbed 0.5-4 keV flux is 3.5(+/-0.3) x 10^-9 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters.
No previously known bright X-ray sources are found within the error circle around the source position. Further follow-up observations are encouraged to identify the nature of this X-ray transient.
The above observations were made with the WXT instrument during the commissioning phase of EP. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36691.
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