GCN Circular 45921
EP261006a: 10 GHz VLA observations
From: unknown
Issued: 2026-10-12 11:42 UTC
Type: X-ray Transient, Radio Transient
M. Yadav, R. Ricci, E. Troja (U Rome) report:
We observed the field of the fast X-ray transient EP261006a (Lao et al. GCN 45826) with the Karl G. Jansky Very Large Array in X-band at the centre frequency of 10 GHz with a bandwidth of 4 GHz on October 10th 2026 at mid-time 10:40 UT(3.7 days after the trigger).
Data were calibrated and imaged using standard procedures in CASA (v6.6.6). 3C48 was used for flux density and bandpass calibration and J0149+0555 was used for complex gain calibration.
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 ~40 uJy/beam.
We thank the VLA staff for executing the observations.
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Relayed automatically from NASA's General Coordinates Network.
Transient Alerts » in reply to EP261006a — X-ray Transient
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.
The whole thread (20 posts)
- EP261006a — X-ray Transient
- EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
- EP261006a : MeerKAT radio observations.
- EP261006a: 10 GHz VLA observations
- EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
- EP261006a: Kilonova-Catcher optical follow-up and detection
- Updated explainer: what the latest reports add (AI-written)
- EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
- EP261006a: Liverpool Telescope optical follow-up
- Explainer: what this is and why it matters (AI-written)
- EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
- EP261006a: Optical follow-up observations with MATCH
- EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
- EP261006a: Swift/XRT detection of the fading X-ray counterpart
- EP261006a: Optical follow-up observations with Kinder
- EP261006a: Liverpool Telescope optical observations
- EP261006a: Early Optical Observations by WFST
- EP261006a: NOT spectroscopy of a blue continuum
- EP261006a: LT and NOT discovery of an optical counterpart
- EP261006a: SVOM/VT optical upper limits
