Einstein Probe detects a short-lived X-ray transient, EP260213a, with no optical counterpart.

AI Summary

EP260213a, a fast X-ray transient lasting 40 seconds, was detected by the Einstein Probe WXT with an average flux of 1.4 × 10^-9 erg/s/cm^2. Follow-up observations by multiple ground-based telescopes did not detect any optical counterparts.

Notices (1)

Einstein Probe WXT — GRB · Fri, 13 Feb 2026 19:58:40 GMT

GCN Circulars (12)

GCN-43823 — EP260213a · Wed, 25 Feb 2026 04:33:50 GMT
The Mephisto team at Yunnan University reported non-detection of a transient object in the EP260213a field using their 1.6m Multi-channel Photometric Survey Telescope. They obtained upper limits in ugiz bands, consistent with previous non-detection reports. Mephisto, the first of its kind in the world, is a 1.6-m wide-field multi-channel telescope capable of simultaneous imaging in three optical bands.

GCN-43739 — EP260213a · Sat, 14 Feb 2026 19:02:18 GMT
A team of astronomers led by the University of Leicester observed the field of a newly discovered X-ray source, EP260213a, using the 2m Liverpool Telescope on La Palma. They reported no detection of new sources within the localization of the X-ray source in the SDSS r' and g' filters. The team derived 3-sigma upper limits of r' > 23.2 and g' > 23.5 for any potential source in the field.

GCN-43738 — EP260213a · Sat, 14 Feb 2026 17:27:19 GMT
The MASTER-Tunka robotic telescope in Russia observed the EP260213a event, located at galactic coordinates (b, l) = (56 deg., 253 deg.), with upper limits of 15.9 and 19.8 mag in clear band filter. The observations began 46720 sec after notice time and 70986 sec after trigger time.

GCN-43737 — EP260213a · Sat, 14 Feb 2026 16:52:46 GMT
A team of international researchers using the COLIBRÍ telescope at the Observatorio Astronómico Nacional in Mexico conducted follow-up observations of the transient event EP260213a. They did not detect any new source at the FXT source position down to 5-sigma limits of r > 24.0 and z > 22.6. This upper limit is consistent with previous reports.

GCN-43735 — EP260213a · Sat, 14 Feb 2026 13:48:03 GMT
Astronomers using the 40cm SLT at the Lulin observatory, as part of the Kinder collaboration, did not detect any new or uncataloged sources within the localization circle of the fast X-ray transient EP260213a in r-band observations. The team used the Python-based AutoPhOT package to perform template subtraction and PSF photometry, resulting in a 3-sigma upper limit of >21.6 mag. The non-detection is consistent with reports from other observatories.

GCN-43734 — EP260213a · Sat, 14 Feb 2026 11:22:32 GMT
Astronomical alert: EP260213a: SVOM/VT optical upper limit

GCN-43733 — EP260213a · Sat, 14 Feb 2026 10:48:57 GMT
A team of astronomers led by N. Pankov at IKI reported no optical detection of the fast X-ray transient EP260213a using the AZT-33IK 1.5m telescope at the Sayan Solar Observatory. No candidate or catalogued objects were found within the error circle. The team's preliminary R-band measurement was 22.2 (3σ upper limit).

GCN-43732 — EP260213a · Sat, 14 Feb 2026 10:20:16 GMT
The NUTTelA-TAO team at Nazarbayev University observed EP 260213a using the Burst Simultaneous Three-Channel Imager (BSTI) following an automated position alert. No optical source was detected above the 5 sigma upper limit sensitivity in Sloan g' and i' bands. The team reports their findings with start times, upper limit magnitudes, and exposure times.

GCN-43731 — EP260213a · Sat, 14 Feb 2026 09:22:49 GMT
The SVOM/C-GFT team reported no credible candidate detection within the error box of a gamma-ray burst (GRB) event EP260213a in follow-up observations using the Chinese Ground Follow-up Telescope. They obtained g, r, and i-band imaging and set 3-sigma upper limits for magnitudes in these bands.

GCN-43730 — EP260213a · Sat, 14 Feb 2026 06:39:43 GMT
The Einstein Probe (EP) mission detected a new X-ray source, EP260213a, using its Wide-field X-ray Telescope (WXT) and Follow-up X-ray Telescope (FXT). The FXT observation, which occurred about 5 minutes after the initial trigger, had an exposure time of approximately 4.7 ks. The source was located at R.A. = 167.0070, DEC = 3.9470 (J2000) with an uncertainty of 10 arcsec. The X-ray spectrum was fitted with an absorbed power law model, revealing a photon index of 2.18 and an unabsorbed flux of 1.77 × 10^(-12) erg/cm^2/s.

GCN-43729 — EP260213a · Sat, 14 Feb 2026 02:42:27 GMT
The Einstein Probe mission, a new X-ray observatory, has detected a fast X-ray transient, EP260213a, with the Wide-field X-ray Telescope (WXT). The transient, located at RA = 167.008 deg, DEC = 3.965 deg, lasted for approximately 40 seconds and had an average flux of 1.4 × 10^-9 erg/s/cm^2 in the 0.5-4 keV energy range. An uncatalogued X-ray source was later detected within the WXT error circle by the Follow-up X-ray Telescope (FXT). The significance of this event lies in the discovery of a new transient X-ray source by the Einstein Probe mission, expanding our understanding of X-ray transients in the universe.

GCN-43728 — EP/WXT 01709258378 · Sat, 14 Feb 2026 01:29:01 GMT
Astronomers using the Nordic Optical Telescope (NOT) did not detect any new sources within the error region of the fast X-ray transient WXT 017709258378, reporting 3-sigma upper limits of r>24.0 and z>22.3 in the AB system for the object.