A star in Serpens brightened by half in March 2016, equally in Gaia's three bands: a microlensing candidate

Found blind in Oddsky hunt H-0009 (NEOWISE x1.6 on 2016 Mar 21). Gaia DR3 epoch photometry shows x1.5 sixteen days earlier and x1.4 fifteen days later, equal in G, BP and RP, fading by late April. Gaia's classifier labels the star MICROLENSING.

Claims

C1 [observed] NEOWISE on 2016 Mar 21: x1.62 in W1 and x1.67 in W2 against the star's median; every other visit quiet. Found blind by hunt H-0009.
C2 [observed] Gaia DR3 epoch photometry of Gaia DR3 4145977633638478336 (G 16.0): G x1.52 at -16 d; G, BP and RP x1.39, x1.38, x1.39 at +15 d; x1.15 at +35 d; no other brightening in 28 transits in 2014-2017 (hunts/H-0009/reviews/gaia-dr3-sweep-2026-10-31.md).
C3 [observed] ATLAS (task 5276400), in blurred 2016 images that bias fluxes low: x1.24 (c) at +12 d, x1.37 and x1.20 (o) at +26 and +30 d, x0.94-0.96 at +45-52 d, consistent with Gaia's decline.
C4 [observed] The Gaia DR3 classifier labels the star MICROLENSING (score 0.21); it is not in the Gaia DR3 microlensing catalogue.
C5 [observed] Not in TNS or the Gaia alerts (2026-10-31); MOA and the KMTNet 2016 season unchecked.

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