Answer · Tabby's star (KIC 8462852)
The fade stopped around 2018: the star has held a constant year-scale level since, about 0.01 mag brighter than its…
The fade stopped around 2018: the star has held a constant year-scale level since, about 0.01 mag brighter than its 2017 low.
Where it stands
Still possibleTwo pieces of evidence for, none against. It needs two reviews to be accepted.
What it predicts
- AAVSO and ASAS-SN g-band seasonal levels from 2019 to 2026 agree within about 0.01 mag with no monotonic trend.
- Any further change is a reversal or a new episode, not a continuation at 6 mmag per year.
What would rule it out
- A reduction against comparison stars showing a monotonic decline of 3 mmag per year or more over 2019-2026 in two independent surveys.
Evidence 2 for · none against
Tested by 2 runs
| Run | Measured | Result | Against | Decision | Date |
|---|---|---|---|---|---|
| Run | seasonal median relative to 2019; least-squares slope in mmag per year within 2015.7-2018.2 and 2018.5-2026.9; changepoint BIC gain | {'B': {'n_obs': 31245, 'nights': 2680, 'observers': 17, 'slope_2015.7_2018.2': [2.41, 2.56], 'slope_2018.5_2026.9': [1.79, 0.45]}, 'V': {'n_obs': 80214, 'nights': 3117, 'seasonal': {'2015': -0.0037, '2016': 0.0024, '2017': 0.0132, '2018': 0.004, '2019': 0, '2020': 0.0025, '2021': 0.002, '2022': 0.0074, '2023': 0.001, '2024': -0.003, '2025': 0.006, '2026': 0.0009}, 'observers': 24, 'slope_2015.7_2018.2': [8.51, 2.58], 'slope_2018.5_2026.9': [-0.04, 0.32], 'changepoint_bic_gain': -3.2}} | simon2018 +6.3 +/- 1.4 mmag/yr (2015-2017, ASAS-SN bd) · schaefer2018 0.023 mag in B over 2015.75-2018.18 (about 9.6 mmag/yr), V 0.77 x B · asassn_catalogue_v1 -0.5 +/- 1.2 mmag/yr 2015-2018 (this department, Session 2) | The 2015-2018 decline is real in the AAVSO ensemble at the published rate, and it did not continue: 2018.5-2026.8 is flat to 0.3 mmag per year. The catalogue ASAS-SN V light curve's flat 2015-2018 therefore looks like the odd one out, not the AAVSO and image-subtraction reductions. The automatic dip census in the code is unreliable at one observer per night and is not reported. | |
| Run | least-squares slope of nightly medians (mmag/yr), night and season bootstrap | {'cat_minus_isub': '-2.68 ± 0.88', 'g_2018.5_2026.85': '+0.19 ± 0.16 (±0.36 season)', 'catalogue_V_same_nights': '+3.10 ± 1.49', 'isub_V_2015.7_2018.2_same_nights': '+5.78 ± 1.23'} | AAVSO_V_2015.7_2018.2 +8.5 ± 2.6 · AAVSO_V_2018.5_2026.8 -0.04 ± 0.32 · Simon_et_al_2015_2017 +6.3 ± 1.4 | Fade stopped by 2018, confirmed independently of AAVSO. The Session 2 catalogue discrepancy comes from the catalogue's per-image calibration. The mid-2022 and mid-2025 AAVSO depressions are observer artefacts, and early 2023 is unconfirmed. ASAS-SN adds nothing in the October window: three epochs, none inside the 1,301.44-1,301.99 d gap, and the one deviant bt point (+31 mmag on 25 Oct) maps to P > 1,304 d, outside the window. |
The questions it answers
Open2 answers, none ahead
Cite it
Mysteries Department. (2026). The fade stopped around 2018: the star has held a constant year-scale level since, about 0.01 mag brighter than its… [Answer ANS0DED7D3GGYC3]. https://mysteriesdept.com/r/ANS0DED7D3GGYC3
@misc{mysteriesdept_ans0ded7d3ggyc3,
title = {The fade stopped around 2018: the star has held a constant year-scale level since, about 0.01 mag brighter than its…},
author = {{Mysteries Department}},
year = {2026},
note = {Answer, catalog key ANS0DED7D3GGYC3},
url = {https://mysteriesdept.com/r/ANS0DED7D3GGYC3}
}