An X-ray transient detected by Einstein Probe shows unusual optical behavior and high-redshift absorption features.

AI Summary

The transient, EP260302a, initially detected by Einstein Probe's WXT, exhibits a rapid decline in X-ray flux and unexpected optical rebrightening. Subsequent observations reveal absorption features indicating a redshift of z=1.535.

Notices (1)

Einstein Probe WXT — GRB · Mon, 02 Mar 2026 23:52:58 GMT

GCN Circulars (10)

GCN-43962 — EP260302a · Wed, 11 Mar 2026 15:56:12 GMT
Astronomers using the MeerKAT radio telescope detected a source at the position of EP260302a, a gamma-ray transient detected by the Einstein Probe, with a flux density of around 170 uJy/beam and image noise of 8 uJy/beam. The observation was made on March 10, 2026 for a total of 44 minutes.

GCN-43935 — EP260302a · Fri, 06 Mar 2026 15:17:15 GMT
The SVOM/VT team reported a Target of Opportunity observation of the transient event EP260302a, which was detected by EP/WXT. The observation was conducted in the VT_B and VT_R channels 55.4 hours after the trigger. The team detected the optical counterpart of the event in both channels, with AB magnitudes of 21.4±0.1 in VT_B and 21.2±0.1 in VT_R.

GCN-43932 — EP260302a · Fri, 06 Mar 2026 09:26:04 GMT
Astronomers using the Gemini-South telescope have determined the redshift of a fast X-ray transient, EP260302a, to be z = 1.535 based on optical spectroscopic observations. The detection of specific absorption features indicates that this object is likely located at this redshift.

GCN-43928 — EP260302a · Thu, 05 Mar 2026 23:34:56 GMT
Astronomers report the detection of the optical counterpart of fast X-ray transient EP260302a using the Gemini South and LCO 1m telescopes. The counterpart exhibited an unexpected rebrightening of approximately one magnitude, which is unusual for FXT and GRB afterglows around this epoch. The team encourages further multiwavelength follow-up of this intriguing source.

GCN-43913 — EP260302a · Tue, 03 Mar 2026 19:18:35 GMT
The MASTER-Net collaboration, including multiple institutions and observatories, reported their observations of transient EP260302a using the MASTER-SAAO robotic telescope in South Africa. The observations began on March 3, 2026, with an upper limit of 18.3 mag in the clear filter. The transient's location is in the galactic coordinates b = -14 deg., l = 282 deg.

GCN-43906 — EP260302a · Tue, 03 Mar 2026 11:54:52 GMT
The Einstein Probe (EP) mission detected a new X-ray transient, EP260302a, on March 2, 2026, with a flux of approximately 1.4 x 10^-10 erg s^-1 cm^-2 and a power-law index of 1.1. A follow-up observation with the EP's Follow-up X-ray Telescope (FXT) revealed a decline in the light curve and a flux of 1.84(+0.05/-0.04) x 10^-10 erg s^-1 cm^-2, a power-law index of 1.46(+0.04/-0.04), and an additional absorption column density of 5.7 (+1.5/-1.4) x 10^20 cm^-2.

GCN-43904 — EP260302a · Tue, 03 Mar 2026 10:57:45 GMT
Astronomers at University College Dublin, PUC, Radboud, and other institutions observed the optical counterpart of the fast X-ray transient EP260302a using the LCO 1m telescope at Cerro Tololo Inter-American Observatory. The counterpart, detected in r and z filters, had magnitudes of 20.84 and 20.38, respectively, and had significantly faded since previous reports. The team confirmed the identification of the counterpart reported by Li et al. and Perez-Garcia et al.

GCN-43903 — EP260302a · Tue, 03 Mar 2026 08:37:18 GMT
The BOOTES-7 robotic telescope at San Pedro de Atacama (Chile) detected the optical counterpart of the fast X-ray transient EP260302a, 11 minutes after its discovery by the Einstein Probe. The optical counterpart was detected within the error circle of the X-ray source and had a magnitude of 19.1. The observation was carried out by a collaboration of institutions and telescopes, including the University of Malaga and the Institute of Astrophysics of Andalusia.

GCN-43899 — EP260302a · Tue, 03 Mar 2026 02:50:49 GMT
The Einstein Probe mission, a new X-ray observatory, has detected an X-ray transient designated EP260302a using its Wide-field X-ray Telescope (WXT). The transient's position was determined with an uncertainty of 3 arcmin using WXT and 20 arcsec using the Follow-up X-ray Telescope (FXT). No further information is available at this time.

GCN-43898 — The EP-WXT trigger 01709258736 · Tue, 03 Mar 2026 02:34:27 GMT
Astronomers using the Las Cumbres Observatory discovered an uncataloged optical source, with a preliminary magnitude of 19.8, approximately one hour after an Einstein Probe WXT trigger. The source is located at RA=132.9739, Dec=-65.9837.