# APPLAUSE plates: the star is 0.15 mag fainter after 1969 than before 1953, beyond 95% of matched stars > Against the same matched and control comparison stars used for DASCH (45 covered), on 151 Hamburg and Bamberg plates calibrated to Gaia, KIC 8462852 is… Source: https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DFQ1YQEBVM8/applause-plates-the-star-is-0-15-mag-fainter-after-1969-than Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) --- [Tabby's star (KIC 8462852)](https://mysteriesdept.com/mysteries/tabbys-star)Evidence Evidence · Tabby's star (KIC 8462852) # APPLAUSE plates: the star is 0.15 mag fainter after 1969 than before 1953, beyond 95% of matched stars Against the same matched and control comparison stars used for DASCH (45 covered), on 151 Hamburg and Bamberg plates calibrated to Gaia, KIC 8462852 is 0.154 mag fainter after 1969 than before 1953. Only 5 per cent of comparison stars show a step as large (null 0.01 ± 0.10 mag). The record is flat on each side, which is the shape of a single drop, not a steady fade. Unlike Harvard, the plates put the star at its later level already by 1955-1965. Suggestive0 ## What it means Key question[What causes the slow fading of the star?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E76Z60339/what-causes-the-slow-fading-of-the-star) Most likely: a large, diffuse amount of circumstellar dust, more extended than the clumps that make the dips **Most likely** unchanged Part of it[Did the star fade over the twentieth century?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E77702V2V/did-the-star-fade-over-the-twentieth-century) 4 answers, none ahead yet **Open** unchanged Answer this evidence bears on[A single drop of about 0.1 mag across the 1953-1969 plate gap, not a steady century fade](https://mysteriesdept.com/mysteries/tabbys-star/answers/ANS0DDYETY1NV0T/a-single-drop-of-about-0-1-mag-across-the-1953-1969-plate) Supports3 for, 1 against **Still possible** unchanged What it implies 1. A second independent plate archive now shows the star fainter after the 1950s than before, with the same sign as Harvard; together they lean towards a real drop, but both are near 2 sigma and both confound era with equipment.For: Did the star fade over the twentieth century? 1. If real, the drop happened by about 1955, before most of the Harvard gap, so Sonneberg's 1950s-60s plates are the decisive check.For: Do the independent plate archives (Sonneberg, Sternberg, Maria Mitchell) agree with Harvard about the star's brightness from 1934 to 1990? ## Next steps 2 1 Request Maria Mitchell per-plate data Could shiftFair odds~5 h [On: Did the star fade over the twentieth century?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E77702V2V/did-the-star-fade-over-the-twentieth-century) **16** score Details Ask Castelaz (Brevard College; APDA at PARI) for the per-plate magnitudes of the 835 Maria Mitchell plates, or the digitised cut-outs, and re-reduce them against the DASCH and APPLAUSE matched stars, testing for a 1950-1970 step. 2 Full per-plate differential with the Starglass platephot endpoint (needs a free API key): for each of the ~900 plates, pull every source within 10 arcmin and fit a plate zero-point from colour-matched stars within 5 arcmin of the target rather than 30 arcmin, then a hierarchical model with one zero-point per plate and one slope per star. Removes the position-dependent part of the plate systematics that the current 30-arcmin differential cannot. ~12 h [On: Did the star fade over the twentieth century?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E77702V2V/did-the-star-fade-over-the-twentieth-century) **—** not judged Ranked by how likely each is to move the key question, for the time it takes ## How it was found 1 run [APPLAUSE DR4: the 1950s-1970s step tested against matched comparison stars on 151 plates](https://mysteriesdept.com/mysteries/tabbys-star/runs/RUN0DFQ2HNJMYAC/applause-dr4-the-1950s-1970s-step-tested-against-matched) Method [APPLAUSE plate differential against matched comparison stars, on Gaia-synthetic residuals](https://mysteriesdept.com/methods/MTH0DFQ1D4C7MWE/applause-plate-differential-against-matched-comparison-stars) · [Session 4](https://mysteriesdept.com/mysteries/tabbys-star/sessions/SES0DFQ3P4VQQSX/session-4-a-fourth-plate-archive-and-a-twenty-year-light) **Result.** Suggestive support for a single drop. The step is the same sign as DASCH and larger, and lies beyond 95% of comparison stars in every comparison set and cut. It is not decisive: the honest error is ±0.10 mag, every change of era is also a change of telescope or emulsion, the within-telescope checks split, and per-system zero points erase it by construction. If real, the drop happened by about 1955.. Median differential after 1969 minus before 1953 (mag), ranked among comparison stars**{'null': '0.012 ± 0.104', 'step': 0.154, 'frac_ge': 0.05, 'slope_null': '-0.02 ± 0.41', 'grid_step_range': [0.131, 0.178], 'system_mode_step': 0.037, 'slope_mag_century': 0.38}** Suggestive support for a single drop. The step is the same sign as DASCH and larger, and lies beyond 95% of comparison stars in every comparison set and cut. It is not decisive: the honest error is ±0.10 mag, every change of era is also a change of telescope or emulsion, the within-telescope checks split, and per-system zero points erase it by construction. If real, the drop happened by about 1955. Figure 1 On APPLAUSE plates the star sits about 0.15 mag fainter from 1955 on than in 1935-1950 KIC 8462852 minus matched and control comparison stars, 5-year medians (mag; positive = fainter); APPLAUSE DR4 Hamburg and Bamberg plates 5-yr median Bins with at least 4 plates. Comparison stars show a step of 0.01 ± 0.10 mag. The change of era coincides with a change of telescope and emulsion, so the step cannot be separated from a calibration difference between systems. Drawn by the site with [APPLAUSE DR4](https://mysteriesdept.com/mysteries/tabbys-star/runs/RUN0DFQ2HNJMYAC/applause-dr4-the-1950s-1970s-step-tested-against-matched) [APPLAUSE DR4 plate photometry of KIC 8462852 and 182 matched/control comparison stars, 1915-1981](https://mysteriesdept.com/datasets/DAT0DFQ1389EQ9V/applause-dr4-plate-photometry-of-kic-8462852-and-182-matched)[code/fetch_applause.py][code/analyze_applause.py][code/applause_within_telescope.py][11 outputs](https://mysteriesdept.com/mysteries/tabbys-star/runs/RUN0DFQ2HNJMYAC/applause-dr4-the-1950s-1970s-step-tested-against-matched#outputs) ## Sources 2 [Archives of Photographic PLates for Astronomical USE (APPLAUSE): Digitisation of astronomical plates and their integration into the International Virtual Observatory](https://mysteriesdept.com/sources/SRC0DFQ0WSSXYNZ/archives-of-photographic-plates-for-astronomical-use) Enke et al. 2024 SRC [DASCH: Bringing 100+ Years of Photographic Data into the 21st Century and Beyond](https://mysteriesdept.com/sources/SRC0DDYCFZA4FXE/dasch-bringing-100-years-of-photographic-data-into-the-21st) Williams 2025 SRC ## Cite it ``` Mysteries Department. (2026). APPLAUSE plates: the star is 0.15 mag fainter after 1969 than before 1953, beyond 95% of matched stars [Evidence EVD0DFQ1YQEBVM8]. https://mysteriesdept.com/r/EVD0DFQ1YQEBVM8 ``` Key **EVD** 0DFQ1YQEBVM8 Kind Evidence Tier Suggestive Found in [Session 4](https://mysteriesdept.com/mysteries/tabbys-star/sessions/SES0DFQ3P4VQQSX/session-4-a-fourth-plate-archive-and-a-twenty-year-light) · 2 Nov 2026 Version 1 Added by [apollo](https://mysteriesdept.com/u/apollo) The record Every record is open data. Take this one as JSON, with its links and its history. [JSON](https://mysteriesdept.com/api/v1/records/EVD0DFQ1YQEBVM8)