TIC 260891473: a candidate detached eclipsing binary identified in TESS photometry

TIC 260891473 is a faint star (Tmag 13.6, Gaia DR3 4624389402114498048) in the southern constellation Mensa. While screening public TESS data for planet candidates that nobody had written up, I found that it dims by about 0.46 per cent every 2.2839 days. At first it looked like a planet. It is not: halfway round the orbit there is a second, much shallower dip (0.53 ppt), and a planet cannot produce one. The system is most likely an eclipsing binary, a K dwarf with a smaller, cooler star crossing its edge. How I got there. I started from the public lists of threshold-crossing events that the SPOC pipeline publishes (340,505 events on 68,319 stars), removed everything already catalogued, and was left with 926 stars worth a closer look. I re-measured their 2-minute light curves myself, and 46 held up. This was one of the cleanest. With 24 sectors of data (S27 to S96) the period is 2.283914 ± 0.000002 d, and the primary eclipse is 4.58 ± 0.13 ppt deep and 2.74 h long. The secondary eclipse shows up separately in three groups of sectors (4.0, 5.2 and 3.4 sigma). Odd and even eclipses match to 0.3 sigma, and the shift of the in-eclipse centroid puts the signal within about 2 arcsec of the star. What is not new. The signal has been seen before. SPOC flagged it as TCE 260891473-01, the ExoMiner++ catalogue (AJ 170, 287) lists its single-sector events as false positives, and a TESS flare study (ApJ 935, 90) lists the star with a rotation period of 2.25 days, close to the orbital period. What I could not find anywhere is an identification of the system as an eclipsing binary: not in the TOI or cTOI lists, VSX, the Gaia DR3 eclipsing-binary table, ASAS-SN-V, SIMBAD, the 74 VizieR catalogues that contain the star, or an ADS full-text search (which would not catch entries buried in tables). What is missing. There are no spectra or radial velocities, so no masses, and I have not fitted a physical eclipse model. The primary eclipse in sector 96 is oddly shallow and I cannot explain it. This is not peer reviewed. "Naz" in the one-page record is an informal nickname I gave the star, not an official name.