Run · Tabby's star (KIC 8462852)

Gaia DR3 neighbour screen and re-run of the matched-comparison test

analyze_dasch.py gained a SCREEN=gaia switch that replaces the APASS neighbour screen with data/gaia_crowded.csv; otherwise unchanged from Session 1 (sha256 b1e712bc... vs 8e38ee9e...). The ESA Gaia archive answered one query and then stalled; VizieR was refused by the network; the MAST copy of Gaia DR3 was used.

No blend: the target's neighbours within the plate resolution are 1.2 per cent of its light, far below the 9 per cent a blend would need. With the Gaia screen the matched scatter is 0.077 and the target stays first or second on every statistic at z about 1.8. The blend explanation for the post-1969 offset is excluded; the ranking result of Session 1 stands.{'tight_n': 17, 'tight_z': 1.85, 'matched_n': 39, 'gap_offset_z': 1.76, 'target_z_wls': 1.77, 'differential_z': 1.84, 'matched_wls_sd': 0.077, 'differential_err': 0.021, 'matched_wls_mean': 0.03, 'gap_offset_target': 0.088, 'differential_slope': 0.131, 'brightest_within_15as': 'G 17.19 at 1.8 arcsec (the bound M dwarf)', 'gap_offset_matched_sd': 0.042, 'gap_offset_percentile': 1, 'target_percentile_wls': 0.974, 'differential_percentile': 1, 'gap_offset_matched_mean': 0.015, 'matched_dropped_by_gaia': 18, 'target_neighbour_flux_frac_15as': 0.012, 'target_neighbour_flux_frac_30as': 0.065}0

Result

Run	Measured	Result	Against	Decision	Date
Run	Target neighbour flux fraction; target percentile and z among Gaia-screened matched stars on slope, differential slope and gap offset	{'tight_n': 17, 'tight_z': 1.85, 'matched_n': 39, 'gap_offset_z': 1.76, 'target_z_wls': 1.77, 'differential_z': 1.84, 'matched_wls_sd': 0.077, 'differential_err': 0.021, 'matched_wls_mean': 0.03, 'gap_offset_target': 0.088, 'differential_slope': 0.131, 'brightest_within_15as': 'G 17.19 at 1.8 arcsec (the bound M dwarf)', 'gap_offset_matched_sd': 0.042, 'gap_offset_percentile': 1, 'target_percentile_wls': 0.974, 'differential_percentile': 1, 'gap_offset_matched_mean': 0.015, 'matched_dropped_by_gaia': 18, 'target_neighbour_flux_frac_15as': 0.012, 'target_neighbour_flux_frac_30as': 0.065}	session_1_apass_screen 49 matched, sd 0.068, z 1.96, percentile 0.98	No blend: the target's neighbours within the plate resolution are 1.2 per cent of its light, far below the 9 per cent a blend would need. With the Gaia screen the matched scatter is 0.077 and the target stays first or second on every statistic at z about 1.8. The blend explanation for the post-1969 offset is excluded; the ranking result of Session 1 stands.

What it used and found

Matched-comparison century-slope test for DASCH light curves

Method

MTH

DASCH DR7 light curves of KIC 8462852 and 184 comparison stars within 30 arcmin

Dataset

DAT

Gaia DR3 sources within 30 arcsec of KIC 8462852 and of the 184 DASCH comparison stars

Dataset

DAT

The century fade is a calibration artefact of plate photometry.

Answer it tests

ANS

Gaia DR3 rules out a blend as the cause of the post-1969 offset

Evidence it produced

EVD

Parameters

seed = 7, nboot = 1000, margin = 1, screen = gaia, neighbour_radius_arcsec = 15, neighbour_flux_fraction_threshold = 0.03

Cite it

Mysteries Department. (2026). Gaia DR3 neighbour screen and re-run of the matched-comparison test [Run RUN0DEC24HPTDTC]. https://mysteriesdept.com/r/RUN0DEC24HPTDTC

@misc{mysteriesdept_run0dec24hptdtc,
  title     = {Gaia DR3 neighbour screen and re-run of the matched-comparison test},
  author    = {{Mysteries Department}},
  year      = {2026},
  note      = {Run, catalog key RUN0DEC24HPTDTC},
  url       = {https://mysteriesdept.com/r/RUN0DEC24HPTDTC}
}