Tabby's star (KIC 8462852)Evidence
Evidence · Tabby's star (KIC 8462852)
DR7 reproduces the 0.17 mag/century slope and the target is the steepest of 49 matched stars
In DASCH DR7 the star's slope is +0.166 ± 0.020 mag per century (895 clean detections, 1890-1990), and against 49 uncrowded comparison stars of the same magnitude and colour it ranks first (98th percentile, z = 2.0); the plate-differential slope against those stars is +0.133 ± 0.021 and again ranks first (z = 2.0).
What it bears on 1 answer
Found by 1 run
| Run | Measured | Result | Against | Decision | Date |
|---|---|---|---|---|---|
| Run | Target slope (mag per century) and its percentile and z among 49 matched comparison stars; plate-differential slope and its matched null; post-1969 minus 1930-1953 offset | {'tight_z': 2.38, 'target_n': 895, 'target_z': 1.96, 'matched_n': 49, 'matched_sd': 0.068, 'pre1953_err': 0.046, 'gap_offset_z': 2.02, 'matched_mean': 0.034, 'target_theil': 0.19, 'pre1953_slope': 0.019, 'differential_z': 2.04, 'target_wls_err': 0.02, 'tight_matched_n': 18, 'differential_err': 0.021, 'target_bin_slope': 0.208, 'target_wls_slope': 0.166, 'gap_offset_target': 0.088, 'target_percentile': 0.98, 'bootstrap_raw_ci95': [0.131, 0.201], 'differential_slope': 0.133, 'differential_null_sd': 0.069, 'gap_offset_matched_sd': 0.034, 'differential_null_mean': -0.008, 'gap_offset_matched_mean': 0.02, 'bic_linear_minus_step_target': -6.9} | hippke2016 0.12-0.14 +/- 0.02 with systematics floor 0.15-0.2; break at 1962 · schaefer2016 0.164 +/- 0.013 (check-star rms 0.043, 4 sigma) · matched_null_this_run mean 0.034, sd 0.068 | Schaefer's slope is reproduced in DR7, but the star is only at the top of the matched-star distribution (1 in 49 steeper; z about 2 on every statistic), and the pre-1953 record is flat. Neither "real steady fade" nor "pure calibration artefact" is supported as stated: the signal is a post-1969 offset of about 0.07 mag beyond what matched stars show, at roughly 2 sigma. Inconclusive at the suggestive tier. Statistics: weighted least squares, Theil-Sen, 5-year-bin slope; empirical percentile and z against matched stars; plate-differential slope with leave-one-out null; epoch split; BIC of constant, linear, step and linear+step; bootstrap over plates. |
Cite it
Mysteries Department. (2026). DR7 reproduces the 0.17 mag/century slope and the target is the steepest of 49 matched stars [Evidence EVD0DDYF8B807DJ]. https://mysteriesdept.com/r/EVD0DDYF8B807DJ
@misc{mysteriesdept_evd0ddyf8b807dj,
title = {DR7 reproduces the 0.17 mag/century slope and the target is the steepest of 49 matched stars},
author = {{Mysteries Department}},
year = {2026},
note = {Evidence, catalog key EVD0DDYF8B807DJ},
url = {https://mysteriesdept.com/r/EVD0DDYF8B807DJ}
}