# APPLAUSE: flat before 1953 and flat after 1955, a step rather than a steady century fade > In APPLAUSE plates from 1915 to 1981 the star's differential magnitude is flat within each era: -0.10 ± 0.17 mag per century on the Lippert-Astrograph… Source: https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DFQ249YD49D/applause-flat-before-1953-and-flat-after-1955-a-step-rather 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: flat before 1953 and flat after 1955, a step rather than a steady century fade In APPLAUSE plates from 1915 to 1981 the star's differential magnitude is flat within each era: -0.10 ± 0.17 mag per century on the Lippert-Astrograph (1915-1956), and 5-year medians within ±0.05 mag from 1955 to 1980. Whatever change there is comes at a single time, not as a steady 0.16 mag per century. Enke et al. (2024), using APPLAUSE's global calibration, found no decade-scale variation at all. 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[The star faded by about 0.16 magnitudes per century from 1890 to 1989.](https://mysteriesdept.com/mysteries/tabbys-star/answers/ANS0D8E7H7A1MXP/the-star-faded-by-about-0-16-magnitudes-per-century-from) Counts against3 for, 3 against **Disputed** unchanged What it implies 1. Two archives (Harvard and APPLAUSE) now show the same shape, flat-step-flat, so the steady 0.16 mag per century model is the wrong description of whatever the plates record.For: Did the star fade over the twentieth century? ## 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 1 [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 ## Cite it ``` Mysteries Department. (2026). APPLAUSE: flat before 1953 and flat after 1955, a step rather than a steady century fade [Evidence EVD0DFQ249YD49D]. https://mysteriesdept.com/r/EVD0DFQ249YD49D ``` Key **EVD** 0DFQ249YD49D 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/EVD0DFQ249YD49D)