{"case":{"id":"OS-0030","title":"An infrared flare in the galaxy NGC 3239 in 2020 that no optical survey saw: an obscured transient","hook":"Found blind by Oddsky's mid-infrared difference imaging of 318 nearby galaxies (hunt H-0012): a flare peaking in 2020 November at about 5e5 L_sun, with no optical alert. Hubble caught a faint point source 85 days after the peak that has since vanished, and JWST found cooling dust at the same spot in 2024.","status":"reproduced","target":{"name":"NGC 3239 IR transient 2020","ra":156.291224,"dec":17.163778,"aliases":[]},"summary":"A mid-infrared flare in the irregular galaxy NGC 3239 (about 8-12 Mpc), peaking in 2020 November at roughly 5e5 L_sun from ~960 K dust, that no optical survey reported. Hubble caught a faint, fading point source 85 days after the peak, and JWST found cooling dust at the same spot in 2024. Probably a dust-obscured stellar merger or eruption; a buried low-energy supernova is possible. Found blind by Oddsky hunt H-0012.","claims":[{"id":"C1","text":"WISE (unWISE neo11 epochal coadds, difference imaging): flat from 2010 to 2020 May 2; on 2020 Nov 23 W1 +232 +- 8 and W2 +308 +- 20 uJy above the 2010-11 level; 91/119 uJy in 2021 Apr, 38/42 in 2021 Nov, ~27 in 2022 Apr. Position 156.29118 +17.16387 (Gaia-tied, ~0.25\"). Positive in both visit seasons, so not an asteroid (hunts/H-0012/reviews/ngc3239-check-2026-11-01.md).","tag":"observed","calls":[],"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"},{"id":"C2","text":"The transient's W1-W2 is 0.95 +- 0.08 (~960 K dust); a blackbody gives ~5.6e5 L_sun at 7.9 Mpc (1.6-2.4x more at the 10-12 Mpc of SN 2012A's host distance and CosmicFlows-4). The rise is unresolved (< 205 d), so the true peak may be higher.","tag":"computed","calls":[],"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"},{"id":"C3","text":"HST (2021 Feb 16): a point source at 156.291224 +17.163778, 0.37\" from the WISE centroid, F606W 25.93 +- 0.06 and F814W 24.95 +- 0.06 AB, present in all four 2021 exposures; absent in 2022 (F606W > 27.1) and in every 2025 filter, with no residual cluster (M_V > -2.9). The chance of an unrelated vanishing source within 0.37\" is ~0.2%.","tag":"observed","calls":[],"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"},{"id":"C4","text":"JWST (programme 3707, 2024 Apr-May): a new unresolved source 0.01\" from the HST position, F335M 5.9 uJy and F300M 3.2-3.6 uJy, nothing in F150W (> 26.5 AB): ~580 K dust at ~3.6e4 L_sun. Spitzer 2008 shows nothing there (> 8 sigma below the 2024 source).","tag":"observed","calls":[],"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"},{"id":"C5","text":"No optical detection: no TNS object or ZTF alert; ATLAS limits o ~20.4-21.7 around the event; the galaxy was in solar conjunction in 2020 August. VLASS < 0.36 mJy (2021 Nov); Chandra 2025 < 2.6e37 erg/s.","tag":"observed","calls":[],"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"},{"id":"C6","text":"Not a buried normal supernova as it stands: the HST colour allows A_V <~ 2, while the faintness relative to WISE needs A_V 9-20, and an enshrouded Type II SN should be 30-100x brighter in the infrared at this phase. An obscured luminous red nova (stellar merger), an ILRT-like eruption (no progenitor seen), or a low-energy SN behind clumpy dust fit better. Not an AGN: 2.7 kpc from the centre of a galaxy with no nucleus.","tag":"inferred","calls":[],"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"},{"id":"C7","text":"Not reported (2026-11-01): TNS, Gaia alerts, CBAT, ATel (web search), SPIRITS, MIRONG, the literature; no publication on the JWST 3707 data at this position. ADS full-text check of the De et al. WISE transient papers still owed.","tag":"observed","calls":[],"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"},{"id":"C8","text":"ADS full text (2026-11-01, hunts/H-0012/work/ads_novelty.json): none of the 67 WISE/NEOWISE transient papers by De et al. and the SPIRITS papers mentions NGC 3239; the 59 papers mentioning NGC 3239 (or Arp 263, UGC 5637) with transient/infrared terms since 2020 are galaxy, ISM and morphology studies and the SN 2012A progenitor-disappearance study, none reporting a 2020 transient; coordinate searches find only unrelated papers. Apparently unreported.","tag":"observed","calls":[],"author":"claude-opus-5.5","at":"2026-11-02T03:55:18+00:00"}],"hypotheses":[{"id":"H1","klass":"eruptive","statement":"A dust-obscured stellar eruption or merger (luminous red nova or ILRT-like event) in NGC 3239, peaking around 2020 November.","supports":["C1","C2","C3","C4","C6"],"conflicts":[],"would_falsify":"A JWST spectrum showing supernova signatures, or a late radio detection of a normal SN.","status":"live","confidence":0.55,"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"},{"id":"H2","klass":"dust_formation","statement":"A low-energy or heavily, clumpily obscured core-collapse supernova whose dust is now cooling.","supports":["C1","C2","C4"],"conflicts":[],"would_falsify":"A spectrum of the remnant without supernova features.","status":"live","confidence":0.35,"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"},{"id":"H3","klass":"artifact_instrumental","statement":"A WISE, HST or JWST artifact, or an unrelated variable star.","supports":[],"conflicts":["C1","C3","C4"],"would_falsify":"Already falsified by three instruments at one position.","status":"rejected","confidence":0.02,"author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00"}],"predictions":[],"literature":[],"hunt":"H-0012","featured":false,"created_at":"2026-11-02T01:26:37+00:00"},"series":{},"context":{},"provenance":{},"skeptic":null,"ledger":[{"id":"K1","tool":"add_claim","args":{"id":"C1","tag":"observed"},"digest":"47420e4be8ce39a8","digest10":"47420e4be8ce39a8","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K2","tool":"add_claim","args":{"id":"C2","tag":"computed"},"digest":"810fe66681869023","digest10":"810fe66681869023","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K3","tool":"add_claim","args":{"id":"C3","tag":"observed"},"digest":"a8e3dde17ac83cf1","digest10":"a8e3dde17ac83cf1","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K4","tool":"add_claim","args":{"id":"C4","tag":"observed"},"digest":"a75fcb10446e9d88","digest10":"a75fcb10446e9d88","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K5","tool":"add_claim","args":{"id":"C5","tag":"observed"},"digest":"0bcef7dd6aaf715f","digest10":"0bcef7dd6aaf715f","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K6","tool":"add_claim","args":{"id":"C6","tag":"inferred"},"digest":"9f5bfdee01c1850d","digest10":"9f5bfdee01c1850d","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K7","tool":"add_claim","args":{"id":"C7","tag":"observed"},"digest":"b95d1853abf18913","digest10":"b95d1853abf18913","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K8","tool":"add_hypothesis","args":{"id":"H1","klass":"eruptive"},"digest":"a3afdee2a580e9e9","digest10":"a3afdee2a580e9e9","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K9","tool":"add_hypothesis","args":{"id":"H2","klass":"dust_formation"},"digest":"3c8ab29249da19db","digest10":"3c8ab29249da19db","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K10","tool":"add_hypothesis","args":{"id":"H3","klass":"artifact_instrumental"},"digest":"98cd99168b0a91ec","digest10":"98cd99168b0a91ec","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K11","tool":"update_hypothesis","args":{"hypothesis":"H3","status":"rejected","confidence":null,"reason":"WISE, HST and JWST see the same unreported object at one position"},"digest":"6bc0da1f42f96fc3","digest10":"6bc0da1f42f96fc3","author":"claude-opus-5.5","at":"2026-11-02T01:26:37+00:00","oddsky":"0.3.1","platform":"darwin-arm64"},{"id":"K12","tool":"add_claim","args":{"id":"C8","tag":"observed"},"digest":"9ad575c09e1ce9ed","digest10":"9ad575c09e1ce9ed","author":"claude-opus-5.5","at":"2026-11-02T03:55:18+00:00","oddsky":"0.3.1","platform":"darwin-arm64"}],"investigations":[],"reviews":[]}