EP240807a, GRB 240807A
GCN Circular 37088
Subject
EP240807a: EP-WXT detection of a fast X-ray transient
Date
2024-08-07T13:07:07Z (10 months ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Y. C. Fu (BNU), S. Q. Jiang, J. W. Hu, Z. X. Ling, W. D. Zhang, Y. Liu, C. C. Jin, C. Zhang, H. Q. Cheng, W. Chen, C. Z. Cui, D. W. Fan, H. B. Hu, M. H. Huang, D. Y. Li, H. Y. Liu, M. J. Liu, Z. Z. Lv, T. Y. Lian, X. Mao, H. W. Pan, X. Pan, H. Sun, W. X. Wang, Y. L. Wang, Q. Y. Wu, X. P. Xu, Y. F. Xu, H. N. Yang, W. Yuan, M. Zhang, W. J. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Y. Chen, S. M. Jia, W. W. Cui, D. W. Han, C. K. Li, L. M. Song, X. F. Zhao, J. Zhang, 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 EP240807a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient started at 2024-08-07T05:42:48(UTC). The WXT position of EP240807a is R.A.= 300.970 deg, DEC = -68.777 deg (J2000) with an uncertainty of 2.5 arcmin (radius, 90% C.L. statistical and systematic). The lightcurve of the transient observed by the WXT lasts around 70 seconds and has a peak flux of ~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 with an absorbed power law with a photon index of 0.9(-0.8, +1.7) (with a freely fitted column density value of 1.1(-1.1, +1.6) x 10^21 cm^-2). The derived average unabsorbed 0.5-4 keV flux is 1.7(-0.6, +0.7) x 10^(-10) 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. Following the WXT detection, we performed a follow-up observation with the Follow-up X-ray Telescope (FXT) on board the EP. Further follow-up observations are encouraged to identify the nature of this X-ray transient.
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).
GCN Circular 37089
Subject
GRB 240807A: Fermi GBM Final Localization
Date
2024-08-07T13:47:38Z (10 months ago)
From
Christian Malacaria at INAF-OAR <cmalacaria.astro@gmail.com>
Via
Web form
The Fermi GBM team reports the detection of a likely Short GRB.
At 05:42:45 UT on 7 Aug 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240807A (trigger 744702170 / 240807238). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 346.2, Dec = -82.6 (J2000 degrees, equivalent to J2000 23h 04m, -82d 34'), with a statistical uncertainty of 7.1 degrees. The angle from the Fermi LAT boresight is 148.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240807238/quicklook/glg_skymap_all_bn240807238.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/bn240807238/quicklook/glg_healpix_all_bn240807238.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240807238/quicklook/glg_lc_medres34_bn240807238.gif
GCN Circular 37097
Subject
EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
Date
2024-08-08T03:01:27Z (10 months ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
J. W. Hu, S. Q. Jiang (NAOC, CAS), Y. C. Fu (BNU) , Z. X. Ling, W. D. Zhang, Y. Liu, C. C. Jin, C. Zhang, H. Q. Cheng, W. Chen, C. Z. Cui, D. W. Fan, H. B. Hu, M. H. Huang, D. Y. Li, H. Y. Liu, M. J. Liu, Z. Z. Lv, T. Y. Lian, X. Mao, H. W. Pan, X. Pan, H. Sun, W. X. Wang, Y. L. Wang, Q. Y. Wu, X. P. Xu, Y. F. Xu, H. N. Yang, W. Yuan, M. Zhang, W. J. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Y. Chen, S. M. Jia, W. W. Cui, D. W. Han, C. K. Li, L. M. Song, X. F. Zhao, J. Zhang, 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
Following the detection of the fast X-ray transient EP240807a (trigger ID 11908397839; Fu et al., GCN 37088), which was temporally coincident with GRB 240807A (Fermi GBM team, GCN 37089), we performed an observation of EP240807a with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation began at 2024-08-07T13:23:29 UTC, about 7.7 hours after the EP-WXT detection. The exposure time is 4434 seconds. Within the error circle of the WXT source, an X-ray source was detected at R.A. = 300.9668 deg, DEC = -68.7861 deg, with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a photon index of 1.65(-0.38, +0.39) (with a fixed Galactic column density value of 5 x 10^20 cm^-2). The derived average unabsorbed 0.5-10 keV flux is 2.8(-0.8, +1.4) x 10^(-13) erg/s/cm^2. There is no cataloged X-ray source within the error circle, suggesting this source being associated with EP240807a.
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).
GCN Circular 37105
Subject
EP EP240807a: Global MASTER-Net observations report
Date
2024-08-08T17:19:34Z (10 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
legacy email
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich
(Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the EP EP240807a ( EP Team et al., GCN 37088) errorbox 47530 sec after notice time and 74246 sec after trigger time at 2024-08-08 02:20:14 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 54 deg. The sun altitude is -38.8 deg.
The galactic latitude b = -32 deg., longitude l = 327 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2554349
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
74277 | 2024-08-08 02:20:14 | MASTER-SAAO | (20h 03m 33.90s , -68d 53m 56.3s) | C | 60 | 18.9 |
74438 | 2024-08-08 02:22:56 | MASTER-SAAO | (20h 03m 35.41s , -68d 53m 48.8s) | C | 60 | 18.9 |
74680 | 2024-08-08 02:26:57 | MASTER-SAAO | (20h 03m 30.34s , -68d 55m 29.0s) | C | 60 | 19.1 |
74918 | 2024-08-08 02:30:55 | MASTER-SAAO | (20h 03m 35.59s , -68d 53m 47.8s) | C | 60 | 19.1 |
75246 | 2024-08-08 02:36:23 | MASTER-SAAO | (20h 03m 35.78s , -68d 54m 57.9s) | C | 60 | 19.1 |
75404 | 2024-08-08 02:39:02 | MASTER-SAAO | (20h 03m 33.13s , -68d 54m 40.4s) | C | 60 | 19.1 |
75642 | 2024-08-08 02:42:59 | MASTER-SAAO | (20h 03m 29.36s , -68d 52m 58.9s) | C | 60 | 19.1 |
75880 | 2024-08-08 02:46:57 | MASTER-SAAO | (20h 03m 36.09s , -68d 54m 30.1s) | C | 60 | 19.2 |
76327 | 2024-08-08 02:54:24 | MASTER-SAAO | (20h 03m 30.54s , -68d 52m 39.0s) | C | 60 | 19.3 |
76564 | 2024-08-08 02:58:22 | MASTER-SAAO | (20h 03m 36.68s , -68d 54m 09.5s) | C | 60 | 19.2 |
76802 | 2024-08-08 03:02:20 | MASTER-SAAO | (20h 03m 35.68s , -68d 52m 35.1s) | C | 60 | 18.8 |
77199 | 2024-08-08 03:08:56 | MASTER-SAAO | (20h 03m 33.53s , -68d 52m 15.9s) | C | 60 | 19.2 |
77278 | 2024-08-08 03:10:16 | MASTER-SAAO | (20h 03m 33.11s , -68d 54m 18.8s) | C | 60 | 19.1 |
77357 | 2024-08-08 03:11:35 | MASTER-SAAO | (20h 03m 37.03s , -68d 52m 13.8s) | C | 60 | 19.2 |
77437 | 2024-08-08 03:12:54 | MASTER-SAAO | (20h 03m 30.88s , -68d 53m 41.7s) | C | 60 | 19.1 |
77516 | 2024-08-08 03:14:14 | MASTER-SAAO | (20h 03m 31.97s , -68d 52m 09.6s) | C | 60 | 19.2 |
77595 | 2024-08-08 03:15:33 | MASTER-SAAO | (20h 03m 35.93s , -68d 53m 39.0s) | C | 60 | 19.1 |
77674 | 2024-08-08 03:16:52 | MASTER-SAAO | (20h 03m 31.16s , -68d 54m 06.4s) | C | 60 | 19.1 |
77753 | 2024-08-08 03:18:11 | MASTER-SAAO | (20h 03m 37.49s , -68d 54m 31.3s) | C | 60 | 19.1 |
77833 | 2024-08-08 03:19:30 | MASTER-SAAO | (20h 03m 34.84s , -68d 52m 03.9s) | C | 60 | 19.1 |
77912 | 2024-08-08 03:20:49 | MASTER-SAAO | (20h 03m 34.39s , -68d 54m 14.4s) | C | 60 | 19.1 |
78155 | 2024-08-08 03:24:53 | MASTER-SAAO | (20h 03m 33.50s , -68d 51m 51.7s) | C | 60 | 19.1 |
78234 | 2024-08-08 03:26:12 | MASTER-SAAO | (20h 03m 37.75s , -68d 53m 21.9s) | C | 60 | 19.2 |
78314 | 2024-08-08 03:27:31 | MASTER-SAAO | (20h 03m 32.97s , -68d 53m 49.3s) | C | 60 | 19.1 |
78393 | 2024-08-08 03:28:51 | MASTER-SAAO | (20h 03m 39.39s , -68d 53m 55.8s) | C | 60 | 19.1 |
78472 | 2024-08-08 03:30:10 | MASTER-SAAO | (20h 03m 36.62s , -68d 52m 11.8s) | C | 60 | 19.1 |
78551 | 2024-08-08 03:31:29 | MASTER-SAAO | (20h 03m 36.29s , -68d 54m 03.2s) | C | 60 | 19.1 |
78794 | 2024-08-08 03:35:32 | MASTER-SAAO | (20h 03m 40.61s , -68d 53m 09.1s) | C | 60 | 19.1 |
79372 | 2024-08-08 03:45:10 | MASTER-SAAO | (20h 03m 42.83s , -68d 53m 05.0s) | C | 60 | 19.1 |
79769 | 2024-08-08 03:51:47 | MASTER-SAAO | (20h 03m 38.55s , -68d 52m 55.1s) | C | 60 | 19.1 |
80178 | 2024-08-08 03:58:36 | MASTER-SAAO | (20h 03m 45.09s , -68d 52m 04.3s) | C | 60 | 19.1 |
80739 | 2024-08-08 04:07:57 | MASTER-SAAO | (20h 03m 46.32s , -68d 51m 41.9s) | C | 60 | 19.0 |
80977 | 2024-08-08 04:11:55 | MASTER-SAAO | (20h 03m 45.52s , -68d 52m 31.5s) | C | 60 | 19.0 |
81532 | 2024-08-08 04:21:10 | MASTER-SAAO | (20h 03m 47.02s , -68d 52m 22.4s) | C | 60 | 18.4 |
81779 | 2024-08-08 04:25:17 | MASTER-SAAO | (20h 03m 55.40s , -68d 53m 16.2s) | C | 60 | 18.0 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 37108
Subject
EP240807a: STEP/T80S optical limits
Date
2024-08-08T22:35:04Z (10 months ago)
From
André Santos at Centro Brasileiro de Pesquisas Físicas (CBPF) <andsouzasanttos@gmail.com>
Via
Web form
A. Santos (CBPF), L. Santana-Silva (CBPF), C. R. Bom (CBPF), C. D. Kilpatrick (Northwestern), P. Darc (CBPF), C. Mendes de Oliveira (IAG-USP) report on behalf of the STEP collaboration:
We conducted optical follow up with the T80S 0.8-m robotic telescope (Santos et al., 2024, MNRAS, 529, 59) of the fast X-ray transient EP240807a discovered by the Einstein Probe (GCN [36691](https://gcn.nasa.gov/circulars/36691). EP240807a was temporally coincident with the Fermi-GBM alert from GRB240807A (GCN 37089) and subsequently localized by the Follow-up X-ray Telescope (FXT) on Einstein probe (GCN 37097). The T80S observations started on August 8 07:40 UT (~16 hours after the trigger). We obtained images totaling 360s (2x180s) in g-band and 720s (3x240s) in r-band with the T80S camera centered at the position of the FXT counterpart at R.A.=20:03:52.90 and Decl.=-68:46:37.20 (J2000). Subtracting DECAM template images from the T80S frames using photpipe (Rest et al., 2005), we do not detect any transient source in our difference images and derive 3-sigma limiting magnitudes of g > 21.9 and r > 22.2 mag for any optical transient.
GCN Circular 37111
Subject
GRB 240807A: SVOM/GRM observation
Date
2024-08-09T09:04:14Z (10 months ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Yong-Wei Dong, Jiang-Tao Liu, Shi-Jie Zheng, Jian-Chao Sun, Wen-Jun tan, Jiang He, Min Gao, Hao-Xuan Guo, Yue Huang, Lu Li, Yong-Ye Li, Hong-Wei Liu, Xin Liu, Hao-Li Shi, Li-Ming Song, You-Li Tuo, Hao-Xi Wang, Jin Wang, Jin-Zhou Wang, Ping Wang, Rui-Jie Wang, Yu-Xi Wang, Bo-Bing Wu, Shao-Lin Xiong, Jian-Ying Ye, Yi-Tao Yin, Wen-Hui Yu, Fan Zhang, Li Zhang, Peng Zhang, Shuang-Nan Zhang, Wen-Long Zhang, Yan-Ting Zhang, Shu-Min Zhao, Xiao-Yun Zhao, Chao Zheng (IHEP), Maria-Grazia Bernardini (LUPM/INAF-OAB), Laurent Bouchet (IRAP), David Corre (CEA), Tais Maiolino (LUPM), Frédéric Piron (LUPM) , Stéphane Schanne (CEA), Jingwei Wang (IAP)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), JeanLuc Attéia (IRAP), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Bing Zhang (UNLV)
report on behalf of the SVOM team:
During the commissioning phase, the SVOM/GRM has detected GRB 240807A which was first detected by EP-WXT (GCN 37088), Fermi/GBM (GCN 37089) and EP-FXT (GCN 37097).
With the event-by-event data downloaded through the X-band ground station, the GRB was detected with a significance of about 6 sigma in the GRM around the Fermi/GBM trigger time at 2024-08-07T05:42:45 UT (T0). The GRM light curve shows that the duration of this burst is about 4 s.
The GRM light curve can be found here:
https://www.bursthub.cn/admin/static/svgrb240807A.png
At the time of this burst, SVOM/ECLAIRs was not in operational mode.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)
GCN Circular 37118
Subject
X-ray Transient EP240807a: PRIME near-infrared upper limits
Date
2024-08-09T20:38:31Z (10 months ago)
From
Joe Durbak at UMD <gcn.joedurbak@gmail.com>
Via
Web form
O. Guiffreda (UMD), J. Durbak (UMD), A. S. Kutyrev (NASA/GSFC), E. Troja (U Rome), K. De (MIT), S. B. Cenko (NASA/GSFC), Atri, S. (U Rome)
Following the Einstein Probe detection (GCN 37088), we observed the transient field in the J filter with PRIME ~21 hours after the EP/WXT detection. The total exposure time of the observation was 1200s.
We report that no new near-infrared detection was discovered within the EP/FXT (GCN 37097) error radius down to ~21.5 AB mag in J band.
At the position of the fast x-ray transient, we detect no uncatalogued source in J band. Using nearby VISTA Hemispherical Survey (VHS) stars for preliminary calibration we derive the following limiting magnitudes, not corrected for Galactic extinction:
Filter | Mag(AB) | Total exposure time (s)
-------|----------------|-------------------------
J | >21.5 +/- 0.1 | 1200
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).
We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations.
GCN Circular 37120
Subject
IPN triangulation of GRB 240807A / EP 240807a
Date
2024-08-09T22:41:04Z (10 months ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A. Ridnaia, D. Frederiks, D. Svinkin, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,
E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team
and
J. DeLaunay, A. Tohuvavohu, S. Barthelmy, J. Cummings, H. Krimm,
and D. Palmer on behalf of the Swift-BAT team, report:
The long-duration GRB 240807A
(Fermi GBM detection: Fermi GBM team, GCN 37089;
SVOM-GRM detection: Wang et al., GCN 37111)
was detected by Fermi (GBM), Konus-Wind, in the waiting mode,
INTEGRAL (SPI-ACS), Swift (BAT), and SVOM (GRM)
at about 20565 s UT (05:42:45).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a GBM-Konus annulus centered at
RA(2000)=295.559 deg (19h 42m 14s) Dec(2000)=-22.821 deg (-22d 49' 15"),
whose radius is 32.402 +/- 32.402 deg (3 sigma).
This localization may be improved.
The fast X-ray transient EP 240807a (Fu et al., GCN 37088; Hu et al., GCN 37097)
is inside the annulus and is consistent with the Konus-Wind ecliptic latitude response, supporting the association of the GRB and EP 240807a.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB240807A/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
GCN Circular 37130
Subject
Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
Date
2024-08-10T11:10:53Z (10 months ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
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 240807A
(Fermi GBM detection: Fermi GBM team, GCN 37089;
SVOM-GRM detection: Wang et al., GCN 37111;
IPN triangulation: Ridnaia et al., GCN 37120)
was detected by Konus-Wind (KW) in the waiting mode
at T0~20568 s UT (05:42:48).
A Bayesian block analysis of the KW waiting mode data
in the 20-300 keV band reveals a >8 sigma count rate
increase in the interval from ~T0+0.143 s to ~T0+3.087 s.
Corrected for the propagation time, the burst started ~4 s
before the start time of the fast X-ray transient EP240807a
(T0(EP)=05:42:48 UT; Fu et al., GCN 37088).
The positional (Ridnaia et al., GCN 37120) and temporal
coincidence of GRB 240807A with the EP transient supports
the conclusion that EP240807a is the GRB counterpart.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240807A/
The time-integrated spectrum of the burst,
measured from T0+0.143 s to T0+3.087 s,
cat be described by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.60(-0.95,+3.74) and Ep = 134(-35,+285) keV.
The total burst fluence is 4.24(-0.01,+4.68)x10^-7 erg/cm^2,
and the 2.944 s peak energy flux, measured from T0+0.143 s,
is 1.43(-0.27,+1.61)x10^-7 erg/cm^2.
(both in the 20 keV - 10 MeV energy range).
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.
GCN Circular 37153
Subject
EP240807a: PRIME H-band upper limits
Date
2024-08-12T17:51:34Z (10 months ago)
From
O. Guiffreda at UMD <oriogui@umd.edu>
Via
Web form
O. Guiffreda (UMD), J. Durbak (UMD), A. S. Kutyrev (NASA/GSFC), E. Troja (U Rome), K. De (MIT), S. B. Cenko (NASA/GSFC), S. Atri(U Rome)
Following the Einstein Probe detection (GCN 37088), we observed the transient field in the H filter with PRIME ~22 hours after the EP/WXT detection. This observation was taken directly after the J-band observations reported in GCN 37118. The total exposure time of the observation was 600s.
At the position of the fast x-ray transient, we detect no uncatalogued source in H band. Using nearby 2MASS stars for preliminary calibration we derive the following limiting magnitudes, not corrected for Galactic extinction:
Filter | Mag(AB) | Total exposure time (s)
-------|----------------|-------------------------
H | >21.1 +/- 0.1 | 600
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).
We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations.