GCN Circular 45874
EP261006a: Optical follow-up observations with MATCH
From: unknown
Issued: 2026-10-09 12:40 UTC
Type: X-ray Transient, Optical Transient
EP261006a (AT 2026aetp, Gaia DR3 2587044864659595392) was first discovered by the Einstein Probe at 2026-10-06T17:49:57 (UTC) ([GCN #45826](GCN - Circulars - Events - EP261006a (gcn.nasa.gov))), and was classified as a possible TDE ([GCN #45831](GCN - Circulars - Events - EP261006a (gcn.nasa.gov))). Subsequent spectroscopic observations revealed a clear blue continuum across the entire spectrum, with no prominent absorption or emission features ([GCN #45833](GCN - Circulars - Events - EP261006a (gcn.nasa.gov))).
We performed follow-up photometric observations of the candidate optical counterpart in the u, g, r, and i bands with the Multi-mode Autonomous Terminal for Compatible Hybrid-optics (MATCH) on 2026 October 8, from 13:54 to 21:45 UT. We selected the image with the best image quality as the reference template and performed image subtraction photometry on it to determine the reference magnitude. We then measured the differential flux in the images after subtraction of the reference template and combined it with the reference flux to derive the light curve over the night.The result shows that the source has brightened in the g, r, and i bands compared to the measurements reported in [GCN #45853](GCN - Circulars - Events - EP261006a (gcn.nasa.gov)) and [GCN #45854](GCN - Circulars - Events - EP261006a (gcn.nasa.gov)). Our photometric measurements are summarized below. The UT listed for each epoch is the mean of the MJD timestamps recorded in the four light-curve files.
| UT | g (mag) | r (mag) | i (mag) | u (mag) |
|---|---|---|---|---|
| 2026-10-08.60253 | 18.313 ± 0.011 | 18.011 ± 0.014 | 17.812 ± 0.022 | 18.419 ± 0.028 |
| 2026-10-08.69608 | 18.317 ± 0.012 | 18.030 ± 0.015 | 17.823 ± 0.019 | 18.340 ± 0.028 |
| 2026-10-08.81616 | 18.295 ± 0.007 | 17.993 ± 0.009 | 17.857 ± 0.029 | 18.333 ± 0.020 |
| 2026-10-08.89243 | 18.279 ± 0.012 | 17.957 ± 0.014 | 17.799 ± 0.024 | 18.379 ± 0.028 |
The Multi-mode Autonomous Terminal for Compatible Hybrid-optics (MATCH) at the Lenghu Observatory, owned and operated by Wuhan University, is a 1-m Ritchey-Chretien system featuring a compact instrument package that integrates both a multi-band photometric camera and a low-resolution spectrograph. For access to raw data or to discuss potential collaboration, please contact Bei You (youbei@whu.edu.cn).
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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: Optical follow-up observations with MATCH
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