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GCN Circular 36888

Subject

EP240708a: X-ray follow-up observations with Swift/XRT

Date

2024-07-16T15:09:00Z (4 months ago)

Edited On

2024-07-19T16:13:19Z (4 months ago)

From

Jonathan Quirola <jaquirola1990@gmail.com>

Edited By

Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Jonathan Quirola <jaquirola1990@gmail.com>

Via

Web form

J. Quirola-Vásquez (Radboud Univ.), P.G. Jonker (Radboud Univ), J. van Dalen (Radboud Univ.) ,F. E. Bauer (PUC), A.J. Levan (Radboud Univ. & Warwick Univ.), D. B. Malesani (DAWN/NBI and Radboud Univ.), Maria E. Ravasio (Radboud Univ.), D. Mata Sanchez (IAC), M.A.P. Torres (IAC), report on behalf of a larger collaboration:

We observed the location of the X-ray counterpart of the fast X-ray transient EP240708a reported by the Einstein Probe WXT instrument and FXT (Chen et al. GCN 36838Not found
 
 
; Hu et al. GCN 36840Not found
 
 
) using the Swift-XRT Observatory ToO program (ObsID: 00016707002). The observation started at 2024-07-15T23:58:44 UT and lasted for ~2.0 ksec, using the PC mode. We do not detect an X-ray counterpart to the transient. Three photons were detected in a ~10" radius centered on R.A. = 345.9641 deg, DEC = -22.8430 deg. Using Kraft et al. (1991) this leads to a 90% upper limit on the source count of ~3.5E-3 cnt/s. Using an absorbed power law model with photon index 1.62 and column density 2.0E20 cm-2 following the detected parameters of Hu et al. (GCN 36840Not found
 
 
), we obtain a flux upper limit of 1.5E-13 erg cm-2 s-1 (0.3-10 keV).

We thank the Neil Gehrels Swift Observatory team for making the X-ray observation possible.