EP241223a
GCN Circular 38660
Subject
EP241223a: EP-WXT detection of a fast X-ray transient
Date
2024-12-24T03:08:39Z (5 months ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
H. Zhou (PMO, CAS), B. -T. Wang (YNAO, CAS), H. Sun, C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team:
We report on the detection of a fast X-ray transient, designated EP241223a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient event was observed to start at 2024-12-23T07:21:23 (UTC). The WXT position of the source is R.A. = 74.804 deg, DEC = 7.110 deg (J2000) with an uncertainty of 3.3 arcmin in radius (90% C.L. statistical and systematic). The transient event lasts for about 80 seconds. The peak flux in the 0.5-4 keV is around 2.4 x 10^-9 erg/s/cm^2. The average 0.5-4 keV spectrum can be fitted with an absorbed power law with a photon index of 2.01(+1.02/-0.85) (with a galactic column density fixed at 1.22 x 10^21 cm^-2). The derived average unabsorbed 0.5-4 keV flux is 9.0(+4.0/-4.0) x 10^-10 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters.
A follow-up observation with the Follow-up X-ray Telescope(FXT) on board EP has been scheduled. Further observations are encouraged to explore the origin of EP241223a.
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.
GCN Circular 38661
Subject
EP241223a: Global MASTER-Net observations report
Date
2024-12-24T04:18:27Z (5 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP241223a ( EP Team et al., GCN 38660) errorbox 101 sec after notice time and 71397 sec after trigger time at 2024-12-24 03:11:20 UT, with upper limit up to 20.8 mag. The observations began at zenith distance = 38 deg. The sun altitude is -32.1 deg.
The galactic latitude b = -20 deg., longitude l = 193 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2720640
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
71427 | 2024-12-24 03:11:20 | MASTER-OAFA | (04h 59m 09.37s , +07d 16m 18.2s) | C | 60 | 20.2 |
71487 | 2024-12-24 03:11:20 | MASTER-OAFA | (04h 59m 09.36s , +07d 16m 18.2s) | C | 180 | 20.8 | Coadd
71939 | 2024-12-24 03:19:52 | MASTER-OAFA | (04h 59m 05.24s , +07d 15m 35.2s) | C | 60 | 20.2 |
72240 | 2024-12-24 03:24:52 | MASTER-OAFA | (04h 59m 11.13s , +07d 15m 44.4s) | C | 60 | 20.2 |
72552 | 2024-12-24 03:30:05 | MASTER-OAFA | (04h 59m 12.82s , +07d 15m 17.8s) | C | 60 | 20.1 |
72612 | 2024-12-24 03:30:05 | MASTER-OAFA | (04h 59m 12.82s , +07d 15m 17.8s) | C | 180 | 20.7 | Coadd
72863 | 2024-12-24 03:35:16 | MASTER-OAFA | (04h 59m 08.75s , +07d 15m 15.0s) | C | 60 | 20.1 |
73175 | 2024-12-24 03:40:27 | MASTER-OAFA | (04h 59m 05.52s , +07d 16m 03.1s) | C | 60 | 20.1 |
73491 | 2024-12-24 03:45:43 | MASTER-OAFA | (04h 59m 11.16s , +07d 16m 09.8s) | C | 60 | 20.2 |
73551 | 2024-12-24 03:45:43 | MASTER-OAFA | (04h 59m 11.16s , +07d 16m 09.9s) | C | 180 | 20.7 | Coadd
73802 | 2024-12-24 03:50:54 | MASTER-OAFA | (04h 59m 10.61s , +07d 15m 22.2s) | C | 60 | 20.1 |
74122 | 2024-12-24 03:56:14 | MASTER-OAFA | (04h 59m 07.99s , +07d 15m 34.7s) | C | 60 | 20.2 |
74443 | 2024-12-24 04:01:35 | MASTER-OAFA | (04h 59m 05.37s , +07d 16m 30.9s) | C | 60 | 20.2 |
74756 | 2024-12-24 04:06:48 | MASTER-OAFA | (04h 59m 10.24s , +07d 16m 38.3s) | C | 60 | 20.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 38665
Subject
EP241223a
Date
2024-12-24T18:00:05Z (5 months ago)
Edited On
2024-12-25T06:39:21Z (5 months ago)
From
Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong@nao.cas.cn>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong@nao.cas.cn>
Via
Web form
Junjie-Jin (NAOC), Haiyang-Mu(NAOC),Zheng-Jie (NAOC), Liguo-Fang (NAOC), Sen-Liu (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report:
We observed the field of the X-ray transient, EP241223a by the Xinglong 2.16-m telescope located at Xinglong, Hebei, China.
Following the detection of EP241223a by EP-WXT (Li et al., GCN 36405), we observed the field of EP241223a using the 2.16-m telescope at Xinglong Observatory, NAOC. We obtained 6x600s clear-band frames with a median time of 2024-12-24T14:16:34, 10 hr after the EP trigger.
No uncatalogued optical transient is detected in the stacked images within the 3 arcmin EP/WXT error circle (Li et al., GCN 36405), down to 5-sigma limiting magnitudes of g ~ 22.5, calibrated with Pan-STARRS sources in the field. Also there is no apparent brightening for the catalogued sources within the error circle.
GCN Circular 38673
Subject
EP241223a: Mondy AZT-33IK optical observations
Date
2024-12-26T15:07:02Z (5 months ago)
From
Nicolai Pankov at HSE, IKI RAS <colinsergesen@gmail.com>
Via
Web form
N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP) report on behalf of the IKI-GRB-FuN collaboration:
We performed optical observations of the field of EP241223a (Zhou et. al, GCN 38660; Lipunov et. al, GCN 38661; Jin et. al, GCN 38665) in the R filter with the 1.5-meter AZT-33IK telescope of Sayan (Mondy) observatory. The observations began on 2024-12-24 14:16 UT, i.e. ~1.3 days since trigger. After the PS1 template subtraction, we do not find any new optical sources in the stacked image of 30*120 sec. The preliminary upper limit is as follows:
Date UTstart t-T0 Exp. Filter OT Err. UL(3sigma)
(mid, days) (s)
2024-12-24 14:16:07 1.30885 30*120 R n/d n/d 21.8
The photometry is calibrated using nearby stars from the USNO-B1.0 catalog (R2 magnitudes) and has not been corrected for the Galactic extinction.