EP241206a

Y.-H. I. Yin (NJU), C. Y. Wang (THU), D. H. Zhao (NAO,CAS), H. W. Pan (NAO,CAS) report on behalf of the Einstein Probe team: 

We report on the detection of a fast X-ray transient detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, EP241206a (Obs. ID: 11900018538 and 11908897056). The transient was first detected with WXT at around 2024-12-06T16:34:47 (UTC) and lasted for about 400 seconds. The WXT position of EP241206a is R.A.= 34.702 deg, DEC = 38.914 deg (J2000) with an uncertainty of 3.78 arcmin (radius, 90% C.L. statistical and systematic). The average 0.5-4 keV spectrum can be fitted with an absorbed power law with a photon index of 1.96 (+0.52/-0.40) (with a column density fixed at the Galactic value of 5.47 x 10^20 cm^-2). The derived average unabsorbed 0.5-4 keV flux is 4.92 (+1.19/-1.24) x 10^(-10) erg/s/cm^2. 

We plan to perform a target of opportunity observation with the Follow-up X-ray Telescope (FXT) on board EP. Further follow-up observations are encouraged to explore the origin of EP241206a. 

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).

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-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the EP241206a ( EP Team et al., GCN 38457
Loading...
 
 ) errorbox  233 sec after notice time and 80029 sec after trigger time at 2024-12-07 14:48:36 UT, with upper limit up to  13.2 mag. Observations started at twilight.  The observations began at zenith distance = 40 deg. The sun  altitude  is -12.9 deg. 

The galactic latitude b = -20 deg., longitude l = 141 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2699396

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   80060 | 2024-12-07 14:48:36 |   MASTER-Kislovodsk | (02h 17m 20.34s , +39d 05m 47.8s) |   C |    60 | 13.2 |        
   82119 | 2024-12-07 15:22:56 |   MASTER-Kislovodsk | (02h 17m 14.23s , +39d 06m 20.8s) |   C |    60 | 13.3 |        
   83468 | 2024-12-07 15:45:25 |   MASTER-Kislovodsk | (02h 17m 08.84s , +39d 06m 27.2s) |   C |    60 | 13.0 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

D.-R. Xiong (Yunnan Observatories of CAS, YNAO), I. Perez-Garcia, E. Fernandez-Garcia, A. J. Castro-Tirado, S.-Y. Wu, M. D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, G. Garcia-Segura (IAA-CSIC), Y.-D. Hu (INAF-OAB), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), Y.-F. Fan, J.-M. Bai, C.-J. Wang, Y.-X. Xin, X.-H. Zhao (YNAO), S. Jeong (ADD, Daejeon) and D. Hiriart and W. H. Lee (UNAM), on behalf of a larger collaboration, report:

Following the detection of EP241206a by the Einstein Probe (Yin et al., GCNC 38457) we triggered our 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) to follow-up this fast X-ray transient starting on Dec. 7 at 13:30 UT (~ 21.1 h after trigger time). No optical afterglow within the EP/WXT error box is detected in the co-added image (15 x 60 s, clear filter) down to 19.2 mag. Later epoch observations were obtained on Dec. 8 at 06:41 UT with the 0.6m BOOTES-5/JGT robotic telescope at San Pedro Martir Astronomical Observatory (Mexico). The resulting co-added frame (10 x 60s, clear filter) imposed a 20.3 mag limiting magnitude.

We thank the staff at both Lijiang and San Pedro Martir observatories for their excellent support.

A. Sota (IAA-CSIC, Granada), D. Calle, L.A. Flores, A. Lamy and R. Orduz (Valencia International University) and A. J. Castro-Tirado (IAA-CSIC), on behalf of a larger collaboration, report:

Following the detection of EP241206a by the Einstein Probe (Yin et al., GCNC 38457) we triggered the 1.5m telescope at Observatorio de Sierra Nevada (Spain) to follow-up this fast X-ray transient starting on Dec. 8 at 19:58 UT (~ 51.4 h after trigger time). No optical afterglow within the EP/WXT error box is detected in the co-added image (11 x 300 s, R-band filter) down to 22 mag. This is consistent with earlier upper limits reported by MASTER (Lipunov et al. GCNC 38458) and the BOOTES Global Network (Xiong et al. GCNC 38466).