No fade in ASAS-SN g after 2018: +0.19 ± 0.16 mmag per year over eight years
If the 2015-2018 fade had continued at the rate image subtraction measures for 2015.7-2018.2 (5.8 ± 1.2 mmag per year in V), the star would be about 0.05 mag fainter in 2026 than in 2018; ASAS-SN g-band image subtraction from two cameras shows +0.19 ± 0.16 mmag per year over 2018.5-2026.85 and a 2026 season 0.1 mmag from the 2019 level, excluding that by more than 15 sigma.
The AAVSO B slope after 2018 (+1.79 ± 0.45 mmag/yr in B) differs from V (-0.04 ± 0.32) by 3.0σ. Re-reduce B against each observer's own comparison star and fit the comparison stars themselves; a drift there is the B band's systematic floor, not the star.
The early-2023 depression is the only one left. Mid-2022 (AAVSO 15.7 mmag, ASAS-SN g 1.5) and mid-2025 (4.2 against -3.5) are AAVSO observer artefacts. Early 2023 is about 10-12 mmag in both records, but ASAS-SN has only ten nights there, at season's end with the star low. Next: reduce each AAVSO observer against their own comparison star (comp1_c/cmag) for January-April 2023, require two observers, and test for an airmass dependence in both records before calling it real.
Ranked by how likely each is to move the key question, for the time it takes
Result. Image subtraction confirms the fade stopped in 2018, independently of AAVSO; the public catalogue's flat 2015-2018 comes from its per-image calibration.
Test · estimate [95% interval]Against the null and the answersVerdict
V fade rate, late 2015 to early 2018, image subtractionmmag per year · null: no fade (0)
+5.78 [+3.37, +8.19]
Excludes no fadep < 0.0001
V fade rate, late 2015 to early 2018, public catalogue, same nightsmmag per year · null: no fade (0)
+3.1 [+0.2, +6.0]
Excludes no fadep = 0.04
g fade rate, mid-2018 to late 2026g band, two cameras · against the two answers
+0.19 [−0.12, +0.50]
Excludes “fade continued”consistent with “fade stopped”
Estimate, 68% interval (thick) and 95% (thin).
Figure 1
The star faded in V until 2018, then held flat in g for eight years
ASAS-SN image-subtraction seasonal medians relative to the first season of each band (mmag; positive = fainter)
seasonal median
Seasons are labelled by the year they end. V is camera bd. g combines cameras bD and bt, tied together to 0.5 mmag. The two bands overlap on only two nights, so their zero points are set separately.
Across the evidence every measurement of the same quantity
Fade rate, late 2015 to early 20185 measurements · 4 with intervals
Pooled, all four+5.5 [+4.0, +7.0]
Disagreement (I²)31%
The measurements agree (I² 31%), so the pooled value stands.
Fade rate, mid-2018 to late 20263 measurements
Pooled+0.3 [+0.1, +0.6]
Disagreement (I²)82%
Against the answers“fade continued” excluded
Every measurement excludes “fade continued”, so it is ruled out whichever is right. They disagree with each other. Next step added Reconcile AAVSO B with the other measurements.
Mysteries Department. (2026). No fade in ASAS-SN g after 2018: +0.19 ± 0.16 mmag per year over eight years [Evidence EVD0DEEBG9PEA7G]. https://mysteriesdept.com/r/EVD0DEEBG9PEA7G
@misc{mysteriesdept_evd0deebg9pea7g,
title = {No fade in ASAS-SN g after 2018: +0.19 ± 0.16 mmag per year over eight years},
author = {{Mysteries Department}},
year = {2026},
note = {Evidence, catalog key EVD0DEEBG9PEA7G},
url = {https://mysteriesdept.com/r/EVD0DEEBG9PEA7G}
}