A star in Scorpius brightened sixfold in 2015, seen by NEOWISE and Gaia: an apparently unreported microlensing candidate

Found blind in Oddsky hunts H-0008/H-0009 (NEOWISE x4.5 on 2015 Sep 7). Gaia DR3 epoch photometry shows the same event, x5.9 seven days earlier and fading over six weeks, equal in BP and RP. Gaia's own classifier labels the star MICROLENSING.

Claims

C1 [observed] NEOWISE on 2015 Sep 7: x4.5 in W1 and x4.8 in W2 against the star's median; every other visit quiet. Found blind by hunts H-0008/H-0009.
C2 [observed] Gaia DR3 epoch photometry of Gaia DR3 5959812622743175552 (G 17.9): G x5.87 on 2015 Aug 30 (7 d before the NEOWISE visit), x2.71 at +25 d and x1.76 at +44 d, with BP and RP rising equally. No other brightening in Gaia's 2014-2017 record (hunts/H-0009/reviews/claude-referee-atlas-2026-10-31.md).
C3 [computed] The event is on Gaia DR3 5959812622743175552, 0.59" from the NEOWISE position, not on the star first matched at 2.2" (which has no epoch photometry): the NEOWISE centroid shifts toward it during the event.
C4 [observed] The Gaia DR3 classifier (variclassifierresult) labels the star MICROLENSING (score 0.60); it is not in the Gaia DR3 microlensing catalogue (varimicrolensing).
C5 [observed] Not in TNS, the Gaia alerts, the KMTNet, OGLE or ZTF lists, VSX, SIMBAD or a web search (2026-10-31). MOA and the KMTNet 2015 season are unchecked. ATLAS did not cover the event (its data start 193 d later).

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