GCN Circular 45874
EP261006a (AT 2026aetp, Gaia DR3 2587044864659595392) was first detected by the Einstein Probe at 2026-10-06T17:49:57 UTC (GCN #45826) and was subsequently suggested to be a possible TDE (GCN #45831). Subsequent spectroscopic observations revealed a clear blue continuum across the entire spectrum, with no prominent absorption or emission features (GCN #45833).
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 and 9. We used archival Pan-STARRS stacked images for g, r, and i and archival SDSS images for u as reference templates. We performed photometry on these images to determine the reference fluxes. We then added the fluxes measured in the reference images to the differential fluxes measured in the difference images to obtain the total fluxes, from which we derived the light curves.Our photometric measurements are summarized below. The UT listed for each epoch is the mean of the MJD timestamps recorded for the available bands at that epoch. A dash indicates that no corresponding measurement is available.
| UT | g (mag) | r (mag) | i (mag) | u (mag) |
|---|---|---|---|---|
| 2026-10-08.58205 | 18.834 ± 0.024 | 18.288 ± 0.016 | 17.986 ± 0.028 | 19.816 ± 0.190 |
| 2026-10-08.62205 | 18.501 ± 0.013 | 18.133 ± 0.010 | 17.867 ± 0.017 | — |
| 2026-10-08.66333 | 18.406 ± 0.011 | 18.113 ± 0.007 | 17.879 ± 0.012 | 19.271 ± 0.174 |
| 2026-10-08.72883 | 18.374 ± 0.011 | 18.043 ± 0.007 | 17.803 ± 0.012 | 19.232 ± 0.174 |
| 2026-10-08.77418 | 18.326 ± 0.011 | 18.023 ± 0.007 | 17.808 ± 0.012 | 18.974 ± 0.174 |
| 2026-10-08.85815 | 18.291 ± 0.011 | 18.008 ± 0.007 | 17.820 ± 0.012 | 18.947 ± 0.174 |
| 2026-10-08.88203 | 18.296 ± 0.011 | 17.959 ± 0.007 | 17.856 ± 0.013 | 19.032 ± 0.174 |
| 2026-10-08.90284 | 18.334 ± 0.011 | 18.095 ± 0.007 | 17.856 ± 0.014 | 18.914 ± 0.174 |
| 2026-10-09.57033 | 18.301 ± 0.011 | 17.933 ± 0.008 | 17.791 ± 0.012 | 18.794 ± 0.026 |
| 2026-10-09.81184 | 18.167 ± 0.013 | 17.885 ± 0.007 | 17.785 ± 0.012 | 18.581 ± 0.025 |
| 2026-10-09.81461 | 18.176 ± 0.013 | 17.911 ± 0.009 | 17.755 ± 0.012 | 18.576 ± 0.022 |
| 2026-10-09.91317 | 18.242 ± 0.011 | — | — | — |
| 2026-10-09.91531 | 18.265 ± 0.011 | — | — | — |
We also converted the differential fluxes into magnitudes.Our measurements show that the source has brightened in the g, r, and i bands compared to the measurements reported in GCN #45853 and GCN #45854.The magnitudes calculated from the differential fluxes are listed below.
| UT | g (without host mag) | r (without host mag) | i (without host mag) | u (without host mag) |
|---|---|---|---|---|
| 2026-10-08.58205 | 19.322 ± 0.035 | 19.505 ± 0.047 | 19.833 ± 0.151 | 19.943 ± 0.194 |
| 2026-10-08.62205 | 18.837 ± 0.015 | 19.087 ± 0.022 | 19.301 ± 0.063 | — |
| 2026-10-08.66333 | 18.710 ± 0.012 | 19.039 ± 0.015 | 19.346 ± 0.045 | 19.346 ± 0.174 |
| 2026-10-08.72883 | 18.667 ± 0.011 | 18.882 ± 0.013 | 19.077 ± 0.038 | 19.305 ± 0.174 |
| 2026-10-08.77418 | 18.606 ± 0.011 | 18.838 ± 0.013 | 19.094 ± 0.038 | 19.031 ± 0.174 |
| 2026-10-08.85815 | 18.560 ± 0.011 | 18.807 ± 0.013 | 19.134 ± 0.039 | 19.002 ± 0.174 |
| 2026-10-08.88203 | 18.566 ± 0.011 | 18.707 ± 0.012 | 19.260 ± 0.045 | 19.092 ± 0.174 |
| 2026-10-08.90284 | 18.616 ± 0.012 | 18.997 ± 0.016 | 19.259 ± 0.049 | 18.968 ± 0.174 |
| 2026-10-09.57033 | 18.573 ± 0.012 | 18.656 ± 0.014 | 19.040 ± 0.037 | 19.144 ± 0.174 |
| 2026-10-09.81184 | 18.404 ± 0.015 | 18.564 ± 0.013 | 19.019 ± 0.036 | 18.919 ± 0.174 |
| 2026-10-09.81461 | 18.415 ± 0.015 | 18.614 ± 0.017 | 18.929 ± 0.034 | 18.914 ± 0.174 |
| 2026-10-09.91317 | 18.498 ± 0.012 | — | — | — |
| 2026-10-09.91531 | 18.528 ± 0.012 | — | — | — |
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).