Two large infrared eruptions 14 years apart in an HII region of M81, the second in 2024

Found by Oddsky's infrared searches of nearby galaxies (hunts H-0012 and H-0013): an obscured source in M81 erupted by 2009 and again in 2023-24, each time reaching about 3e5 Lsun in the infrared, with nothing seen between.

An obscured source in an HII region of M81 (3.6 Mpc) that erupted in the infrared by 2009 and again in 2023-24, each time reaching about 3e5 Lsun, with nothing between. Probably recurrent eruptions of a massive star; a long-period dust maker or two unrelated events are possible. Post-2024 infrared data would tell. Found by Oddsky hunts H-0012 and H-0013.

Claims

C1 [observed] Spitzer: flat 2003.8-2005.0, then +196 uJy at 2009.9 declining to +98 uJy by 2010.4; WISE 2010 agrees (hunts/H-0013/README.md).
C2 [observed] WISE: flat 2014-2023, then a sharp rise in 2023.9-2024.4 to W1 0.75 / W2 1.0 mJy (about 3e5 Lsun at 3.6 Mpc). H-0012 v2 ranks it 8th among obscured transients (hunts/H-0012/work/triageh0012b.csv).
C3 [observed] It sits on a giant molecular cloud / HII region next to a blue Gaia source (G = 20.25, BP-RP = 0.37, MG about -7.5); the nearest TNS object is AT 2026dvq, 22.6" away.
C4 [observed] Not reported (2026-11-02): ADS full text for the coordinates and for the host with variability terms finds nothing on this source; nothing in TNS, SIMBAD, Gaia DR3, AllWISE or the Spitzer SEIP catalogue at the position; nothing within 10" in the SPIRITS catalogue of luminous long-period variables, which covers M81.

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