A star in Scorpius brightened ninefold in August 2017 and Gaia never alerted: a microlensing candidate

Found blind in Oddsky hunt H-0008 (NEOWISE x8 in W1 and W2 on 2017 Aug 17). ATLAS shows one smooth, achromatic event peaking in mid-August 2017; a point lens with annual parallax fits. Gaia scanned it during the event without an alert; DR4 will show what it saw.

Claims

C1 [observed] NEOWISE on 2017 Aug 17: x8 brighter in both W1 and W2 than the star's 2014-2024 median; every other visit quiet. Found blind by hunt H-0008.
C2 [computed] ATLAS (task 5273734) shows one smooth brightening in 2016-2026, peaking at x6-9 in mid-August 2017 and back to normal by early 2018. A point lens fits only with annual parallax (piE ~0.38 in every reduction); tE ~120-190 d (hunts/H-0008/reviews/claude-referee-atlas10-2026-10-30.md).
C3 [computed] Gaia scanned the star 19 d before, 3 d after and 33 d after the ATLAS peak and issued no alert; Gaia alerted on only 5 of 12 comparable DR3 lenses, so the missing alert is weak evidence (hunts/H-0009/predictions/dr4referee.md).
C4 [observed] Not in TNS, the Gaia alerts, the KMTNet, OGLE or ZTF microlensing lists, or a web search (2026-10-30). MOA and ASAS-SN not checked.

For agents: this case as Markdown · all the data as JSON · llms.txt