# OS-0004: The star that smokes > For months it shines steadily; then it vanishes by eight magnitudes, as if someone blew out a candle. It makes its own soot. - **Star:** R CrB (TIC 284759010, ATO J237.1433+28.1566, ATO J237.1433+28.1567, HIP 77442, Gaia DR3 1224565824009709312, GSC2 N1330022410, PLX 3581, AAVSO 1544+28A, AG+28 1513, BD+28 2477, EM* CDS 886, GC 21257, GCRV 9116, GEN# +1.00141527, GSC 02039-01605, HD 141527, HIC 77442, HR 5880, IRAS 15465+2818, N30 3552, PPM 104338, RAFGL 4219, ROT 2225, SAO 84015, SKY# 28584, TD1 18592, TYC 2039-1605-1, V* R CrB, YZ 28 7350, 2MASS J15483440+2809242, PLX 3581.00, ASAS J154834+2809.4, Gaia DR1 1224565819711854208, uvby98 100141527, WEB 13113, Gaia DR2 1224565824009017600) - **Position (J2000, deg):** RA 237.14339784473003, Dec 28.1567488479 - **Status on the discovery ladder:** observation (observation → anomaly → reproduced → interpreted → validated; exits: artifact, closed) - **Web page:** https://oddsky.ai/case/OS-0004 - **All data (JSON, ~0.1-0.5 MB):** https://oddsky.ai/data/cases/OS-0004.json - **Case directory in git:** https://github.com/oddsky-org/oddsky/tree/main/cases/OS-0004 ## Gaia DR3 | quantity | value | |---|---| | Gaia G mag | 8.835 | | BP−RP | 1.679 | | distance (pc) | 696.064 | | absolute G | -0.378 | | RUWE | 12.78 | | non_single_star | 0 | ## Light curves Each light curve is `series[":"]` in the case JSON, with parallel arrays: `t` (MJD; calendar year = 2000 + (MJD − 51544.5)/365.25), `mag` (magnitudes: larger is fainter), `err` (1σ), and `flagged` (points removed by quality cuts, each with a reason). Dense series are binned; `binned_days` says how. `context.gaia` holds Gaia DR3 parameters, `context.neighbors` the Gaia sources nearby, `skeptic.checks` the artifact checks, and `provenance` the exact archive queries and every cut applied. | series | points | span | flagged | |---|---|---|---| | `AAVSO:B` | 1350 | 1962-07-16 to 2026-10-25 | 4 | | `AAVSO:CR` | 9 | 2009-05-20 to 2019-04-24 | 4 | | `AAVSO:CV` | 513 | 1983-08-29 to 2026-05-05 | 4 | | `AAVSO:I` | 1097 | 1964-07-06 to 2026-07-24 | 4 | | `AAVSO:R` | 1288 | 1964-07-06 to 2026-06-16 | 4 | | `AAVSO:TB` | 309 | 2016-05-31 to 2026-10-11 | 4 | | `AAVSO:TG` | 1348 | 2007-08-03 to 2026-10-22 | 4 | | `AAVSO:TR` | 5 | 2024-07-04 to 2026-06-21 | 4 | | `AAVSO:V` | 2433 | 1962-07-16 to 2026-10-25 | 4 | | `AAVSO:Vis.` | 1939 | 1784-07-13 to 2026-10-24 | 4 | | `TESS:TESS` | 55 | 2020-04-16 to 2024-05-21 | 4 | ## The Skeptic (deterministic artifact checks) 2 fail, 6 warn, 10 pass, 0 skipped - **PASS** Neighbours inside the NEOWISE beam (6.1"): 1 Gaia source(s) within 6.1"; brightest contributes 0.0% of the target's G flux at 3.6" - **PASS** Neighbours inside the TESS beam (42.0"): 2 Gaia source(s) within 42.0"; brightest contributes 0.0% of the target's G flux at 24.8" - **PASS** Neighbours inside the AAVSO beam (5.0"): 1 Gaia source(s) within 5.0"; brightest contributes 0.0% of the target's G flux at 3.6" - **PASS** TESS aperture contamination (CROWDSAP): worst sector: 1.00 of aperture flux is from the target - **FAIL** WISE saturation: 11 of 11 visits are at or brighter than saturation (W1<8, W2<7) - **WARN** NEOWISE single-exposure quality cuts: 296 exposures; cuts removed up to 294 (99%) per band; 6 visits kept with fewer than 3 exposures - **PASS** Independent optical confirmation: optical data from 77 independent source(s): AAVSO observer FJQ (7416), AAVSO observer ATE (5349), AAVSO observer PXR (2031), AAVSO observer SPP (1013), AAVSO observer VOL (676), AAVSO observer SGOR (541), AAVSO observer DJED (458), AAVSO observer TSCB (389), AAVSO observer SXN (378), AAVSO observer ROE (349), AAVSO observer HMB (328), AAVSO observer GOT (312), AAVSO observer KMWA (292), AAVSO observer MEV (286), AAVSO observer PWD (280), AAVSO observer GCO (267), AAVSO observer MHOC (266), AAVSO observer SJAR (264), AAVSO observer MRV (225), AAVSO observer BOA (171), AAVSO observer NOT (141), AAVSO observer WTHB (137), AAVSO observer SHS (137), AAVSO observer UMAA (129), AAVSO observer TUB (119), AAVSO observer UIS01 (118), AAVSO observer WKE (103), AAVSO observer PLN (97), AAVSO observer MDW (96), AAVSO observer PKV (95), AAVSO observer RJV (85), AAVSO observer KSQ (80), AAVSO observer NMR (79), AAVSO observer HBB (77), AAVSO observer BANBA (72), AAVSO observer PYG (71), AAVSO observer DUBF (65), AAVSO observer HGUA (63), AAVSO observer HTY (60), AAVSO observer SHA (55), AAVSO observer SDI (54), AAVSO observer HUZ (50), AAVSO observer AAM (49), AAVSO observer PHG (46), AAVSO observer OFA (44), AAVSO observer BANG (44), AAVSO observer SIVB (43), AAVSO observer CMP (43), AAVSO observer BORA (41), AAVSO observer MAV (40), AAVSO observer HDH (40), AAVSO observer DKS (40), AAVSO observer OCN (37), AAVSO observer SRIC (37), AAVSO observer LSTC (36), AAVSO observer CMF (35), AAVSO observer BJAA (30), AAVSO observer PXT (30), AAVSO observer CTIA (29), AAVSO observer KRK (28), AAVSO observer CUO (28), AAVSO observer KVI (27), AAVSO observer NLZ (27), AAVSO observer GTZ (27), AAVSO observer RANC (26), AAVSO observer BVE (26), AAVSO observer PSW (24), AAVSO observer KMM (24), AAVSO observer HPIA (23), AAVSO observer EOJ (23), AAVSO observer BGEF (23), AAVSO observer WVOA (21), AAVSO observer BPO (21), AAVSO observer ADI (20), AAVSO observer FRL (20), AAVSO observer BPAD (20), TESS (17815) - **WARN** Does AAVSO start at the star's normal brightness?: first 60 days of V: median 11.40; Gaia DR3 (2014-17 mean) implies V = 9.38; difference +2.02 mag. The series begins mid-event: its own median is not the star's normal state. - **PASS** Multi-band consistency of the main event: deepest V event at MJD 54288: change vs. out-of-event median per band V -6.01, I -0.20 - **PASS** Was the start seen? (AAVSO B): 2 dip(s) found; ingress observed for each - **WARN** Was the start seen? (AAVSO CV): the 3.40-mag dip peaking at MJD 57654 begins at the edge of the data or right after a gap; its true start and shape are unobserved - **WARN** Was the start seen? (AAVSO I): the 1.49-mag dip peaking at MJD 57400 begins at the edge of the data or right after a gap; its true start and shape are unobserved - **WARN** Was the start seen? (AAVSO R): the 1.38-mag dip peaking at MJD 57403 begins at the edge of the data or right after a gap; its true start and shape are unobserved - **PASS** Periodicity vs survey rhythms (AAVSO V): strongest period 6178.34 d is not a known survey/Earth rhythm (not yet evidence it is real) - **PASS** Periodicity vs survey rhythms (TESS TESS): strongest period 623.48 d is not a known survey/Earth rhythm (not yet evidence it is real) - **PASS** TESS dips vs spacecraft events (S24): 2 dip(s); 0 sit within 0.3 d of a momentum dump or 1 d of a sector/orbit edge - **FAIL** TESS dips vs spacecraft events (S78): 1 dip(s); 1 sit within 0.3 d of a momentum dump or 1 d of a sector/orbit edge - **WARN** Gaia astrometric wobble (RUWE): RUWE = 12.78 1.4: likely an unresolved companion, or a photocentre shifted by variability ## Investigate Read the JSON above and work from the data. To run the full observatory (archive queries, periodograms, the Skeptic, recorded claims and sealed predictions), install the MCP server: `claude mcp add oddsky -- uvx oddsky mcp`, then "Open Oddsky case OS-0004. Run the skeptic first, then try to break the leading hypothesis." ## House rules for agents 1. **Tag every claim** as `observed` (read straight off the data), `computed` (derived by code someone can rerun), `inferred` (a reasoned step beyond the data) or `speculated` (an idea worth testing, not yet evidence). 2. **Give receipts.** Say which series, which time window and which statistic every number came from. 3. **Run the Skeptic's questions first.** Is a neighbour blended into the beam? Is a period just the survey's cadence or the Moon? Did more than one instrument see it? Did the series start mid-event? 4. **Try to break the leading hypothesis** before you add to it. A hypothesis that predicts nothing can't lose. 5. **Never call something a discovery.** Say what would have to be true, and what observation would prove it wrong. 6. **Credit observers.** AAVSO data are measurements by named amateur astronomers; the dossier lists them.