Einstein Probe detects fast X-ray transient EP260214b with follow-up optical and radio observations

AI Summary

The Einstein Probe WXT detected a 50-second X-ray transient with an average flux of 2.1 × 10^(-9) erg/s/cm^2. Follow-up observations revealed an optical counterpart at a redshift of 1.208, while radio searches yielded no significant emission.

Notices (1)

Einstein Probe WXT — GRB · Sat, 14 Feb 2026 22:04:12 GMT

GCN Circulars (16)

GCN-44088 — EP260214b · Mon, 23 Mar 2026 15:25:11 GMT
A team of astronomers led by INAF-IAPS reported the detection of radio emission from the Fast X-ray Transient EP260214b using the Australian Telescope Compact Array (ATCA) at a flux density of ~0.04 mJy. This detection, which occurred approximately 34 days after the initial trigger, marks the first radio detection of this transient.

GCN-43924 — EP260214b · Thu, 05 Mar 2026 15:31:04 GMT
A team of astronomers led by INAF-IAPS reported non-detection of radio emission from the Fast X-ray Transient EP260214b at 6 GHz using the Australian Telescope Compact Array for 6 hours. The 3-sigma upper limit is ~50 uJy.

GCN-43775 — EP260214b · Tue, 17 Feb 2026 17:29:43 GMT
A team of astronomers led by A. Volnova at IKI RAS have observed the optical counterpart of the fast X-ray transient EP260214b using the AZT-33IK 1.5m telescope at Mondy observatory. The optical emission was detected in a stacked frame and preliminary photometry shows a magnitude of 21.67 with an error of 0.16 and an upper limit of 23.0. The event is located at a redshift of 1.208 and was previously reported by various teams.

GCN-43774 — EP260214b · Tue, 17 Feb 2026 17:26:03 GMT
A team of astronomers led by Debalina Kar at ARIES used the 1.3m Devasthal Fast Optical Telescope to observe the error box of a gamma-ray burst detected by EP/WXT. They did not detect any optical counterpart within the error box, reporting a 3-sigma upper limit of >22.40 mag in the R filter. This non-detection is consistent with previous reports and adds to the evidence that this gamma-ray burst may have been a faint or extincted event.

GCN-43764 — EP260214b · Mon, 16 Feb 2026 14:12:34 GMT
Astronomers at Liverpool John Moores University used the Liverpool Telescope to observe EP 260214b, a transient object reported by multiple sources. They obtained optical images in g, r, and i filters and detected signals in all three, reporting magnitudes of 22.45±0.27 for g, 22.22±0.33 for r, and 21.75±0.24 for i. The observations were taken approximately 28.8 hours after the trigger.

GCN-43762 — EP260214b · Mon, 16 Feb 2026 10:28:20 GMT
A team of astronomers led by A. Aryan from National Central University reported non-detection of the proposed optical counterpart of the fast X-ray transient EP260214b using the 1m LOT at the Lulin observatory as part of the Kinder collaboration. They did not detect the object in stacked or difference images, and obtained a 3-sigma upper limit of r > 22.2 mag. This non-detection is consistent with previous reports and upper limits from other teams.

GCN-43760 — EP260214b · Mon, 16 Feb 2026 05:59:28 GMT
The Einstein Probe mission detected a new fast X-ray transient, EP260214b, using its Wide-field X-ray Telescope. The transient was later observed by the FXT instrument on the same mission, and an uncatalogued X-ray source was identified within the error circle. The source was found to have an unabsorbed flux of approximately 2.8 x 10^-13 erg/s/cm^2 in the 0.5-10 keV energy range.

GCN-43758 — EP260214b · Sun, 15 Feb 2026 20:17:14 GMT
A team of astronomers led by Rosa L. Becerra at UNAM observed the optical counterpart of transient event EP260214b using the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional. They detected the transient at a preliminary AB magnitude of 21.08 +/- 0.23, consistent with previous observations. The team thanks the staff of the observatory for their support.

GCN-43757 — EP260214b · Sun, 15 Feb 2026 18:57:19 GMT
A team of astronomers from IIT Bombay and Indian Institute of Astrophysics used the GROWTH-India Telescope to observe the field of EP260214b, a transient event detected by the Einstein Probe mission. They did not detect any transient in their single exposure in the r' filter with an upper limit of magnitude 20.9, obtained after 18.4 hours from the trigger. The measurement is consistent with other optical observations.

GCN-43755 — EP260214b · Sun, 15 Feb 2026 16:46:31 GMT
The Space Variable Objects Monitor (SVOM) team reported a Target of Opportunity observation of gamma-ray burst EP260214b, detected by Einstein Probe, using the VT instrument. The optical counterpart was detected in both VT_B and VT_R channels, with measured magnitudes of 21.29 ± 0.08 mag and 20.84 ± 0.07 mag, respectively. No significant variation was observed during the 2.27 hour observation period.

GCN-43752 — EP260214b · Sun, 15 Feb 2026 14:06:52 GMT
A group of astronomers led by D. Russeil et al. observed the optical counterpart of the gamma-ray burst EP260214b using the T120cm telescope at Observatoire de Haute-Provence. They measured a preliminary magnitude of r = 21.22 ± 0.13 mag (AB) for the object, which is located at a redshift of 1.208.

GCN-43750 — EP260214b · Sun, 15 Feb 2026 11:37:27 GMT
Astronomers at the Instituto de Astrofisica de Canarias and University of La Laguna detected the optical counterpart of the fast X-ray transient EP260214b using the Las Cumbres Observatory 1-m telescope. The object, located at a redshift of 1.208, was observed 11.34 hours after the X-ray trigger and had an AB magnitude of r' = 21.28 +/- 0.09. This discovery was made using the Astro-COLIBRI platform and the Las Cumbres Observatory global telescope network.

GCN-43749 — EP260214b · Sun, 15 Feb 2026 10:06:03 GMT
Astronomers using the ESO/VLT UT3 telescope with the X-shooter spectrograph have detected a redshift of z = 1.208 for the optical counterpart of a gamma-ray burst (EP260214b), discovering multiple absorption lines from Al II, Fe II, Mg II and emission lines from [O II], Ne III, [O III], and Balmer lines from the host galaxy.

GCN-43747 — EP260214b · Sun, 15 Feb 2026 06:40:56 GMT
A team of astronomers led by Alan Watson at UNAM observed the optical counterpart of the transient EP260214b using the DDRAGO imager on the COLIBRÍ telescope. They detected the source, which was previously reported by He et al., and measured its magnitudes in the g, r, i, and z filters. The source had faded slightly since the previous observation, suggesting a plateau in its light curve. The optical counterpart also had blue colors, consistent with a nearby event and the high X-ray flux reported earlier.

GCN-43745 — EP260214b · Sun, 15 Feb 2026 05:27:38 GMT
A team of astronomers led by L.B. He at NAOC and HUST report the detection of a brightened source in the field of EP260214b using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. The source, located at R.A.(J2000) = 191.2582, Dec.(J2000) = 23.8536, is ~2.0 mag brighter than its underlying host galaxy and has a photometric redshift of z ~ 1.04. The team suggests this source may be the optical counterpart of EP260214b.

GCN-43744 — EP260214b · Sun, 15 Feb 2026 05:11:36 GMT
The Einstein Probe mission, a space X-ray observatory, detected a fast X-ray transient designated EP260214b on February 14, 2026. The transient, located at R.A. = 191.26°, DEC = 23.857° (J2000), lasted approximately 50 seconds and had an average flux of 2.1 (-0.5/+0.7) × 10^(-9) erg/s/cm^2 in the 0.5-4 keV energy range. A follow-up observation with the Follow-up X-ray Telescope (FXT) confirmed the detection of an uncatalogued X-ray source within the WXT error circle.