Transient Alerts — HabitableZone

Transient Alerts » in reply to EP261006a — X-ray Transient

In plain words Notable

On 6 October 2026 the Einstein Probe, a space X-ray telescope, spotted a sudden flash of X-rays at the position of a galaxy, with a measured redshift of 0.1853 (very roughly 2-3 billion light-years away). Optical telescopes then found a bright, blue, new light source right at the galaxy's centre that was not there two days earlier and has brightened to about 18th magnitude over several days. Its blue colour and central location fit a tidal disruption event, where a black hole tears apart a passing star, but the spectra show no clear features to confirm this, and a fast-fading exploding star remains possible. The X-rays faded by about a factor of 300 within a day, while the visible light kept rising, so the two may not come from the same process. Radio telescopes (VLA and MeerKAT) detected nothing.

How unusual is it? A measured distance, an optical counterpart at the galaxy's centre and a rising blue light curve make this a well-characterised fast X-ray transient, with a likely tidal disruption event, which is more than the typical alert. It is not exceptional, since such events are being found regularly, and the classification is still unconfirmed; clear emission lines or radio emission would settle the nature, and a different type of explosion would change the picture.

Written by an AI model (claude-sonnet-5-5) from the official reports in this thread, and rewritten as new reports arrived (version 7); last updated . It may contain mistakes: the reports themselves are the authority.

EP261006a : MeerKAT radio observations.
GCN Circulars —

GCN Circular 45947
EP261006a : MeerKAT radio observations.
From: unknown
Issued: 2026-10-14 10:18 UTC
Type: X-ray Transient, Radio Transient

S. Corbel, N. Grollimund (Université Paris Cité & CEA Saclay), Chichuan Jin (National Astronomical Observatories), Alexis Coleiro, Zheyu Lin (Université Paris Cité) report :

We observed the field of the fast X-ray transient EP261006a (Lao et al. GCN 45826) with the MeerKAT radio telescope at two frequencies: L-band [central frequency: 1.284 GHz / Bandwidth: 856 MHz] and S-band [central frequency: 3.062 GHz / Bandwidth: 875 MHz]

Data were calibrated and imaged using standard procedures. J1939-6342 was used for flux density and bandpass calibration whereas J0108+0134 (L-band) /J0121+0422 (S-band) were used for complex gain calibration.

Observations were conducted on two days:

2026-10-09 (16 min/band),
L-band
Start: 2026-10-09 20:41:01 UTC
Central MJD 61322.87 (t-t0 = 3.12 days)

S-band
Start: 2026-10-09 19:42:28 UTC
Central MJD 61322.83 (t-t0 = 3.08 days)

and

2026-10-11 (16 min/band)
L-band
Start: 2026-10-11 20:02:31 UTC
Central MJD 61324.84 (t-t0 = 5.10 days)

S-band
Start: 2026-10-11 18:48:18 UTC
Central MJD 61324.79 (t-t0 = 5.05 days)

By combining both observations per band, no radio source is detected at the candidate optical counterpart (Eyles-Ferris et al. GCN 45831; Wu et al. GCN 45852; Bochenek & Perley GCN 45853; Chen et al. GCN 45854) down to a preliminary 3-sigma upper limit of 39 uJy/beam (L-band) and 27 uJy/beam (S-band). This is in agreement with the concomitant non detection reported by the VLA at 10 GHz around the same period (Yadav et al. GCN 45921).

We thank the SARAO staff for rapidly scheduling these observations. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. This work has made use of the "MPIfR S-band receiver system" designed, constructed and maintained by funding of the MPI für Radioastronomie and the Max-Planck-Society.

Filter: only the top 10% of the past year's X-ray transients are posted, ranked by the number of GCN Circulars written about them (now ≥ 11). Thresholds are recalculated monthly. Only events first reported within the past 7 days can start a thread.
Relayed automatically from NASA's General Coordinates Network.

Log in or register to post.

The whole thread (20 posts)

Related discussions