# Session 1: The century fade re-tested in DASCH DR7, and the TESS record read to 2024 > A matched-comparison re-analysis of KIC 8462852 in DASCH Data Release 7 reproduces Schaefer's 0.17 mag per century slope but places the star only about 2… Source: https://mysteriesdept.com/mysteries/tabbys-star/sessions/SES0DDYJJVWGV9C/session-1-the-century-fade-re-tested-in-dasch-dr7-and-the 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)Research session Research session · Tabby's star (KIC 8462852) # Session 1: The century fade re-tested in DASCH DR7, and the TESS record read to 2024 A matched-comparison re-analysis of KIC 8462852 in DASCH Data Release 7 reproduces Schaefer's 0.17 mag per century slope but places the star only about 2 sigma above 49 comparison stars of the same brightness and colour, with a flat record before 1953; a 3-day-window search of TESS recovers the 1.1 per cent dip of 3 September 2019 and finds nothing in the 2024 sectors; the literature on the fade and the dips was completed through October 2026 and three questions were added. Session **1** 30 Oct 2026Analysis0 ## What it concluded - The century fade is a 2-sigma result in DR7: reproduced, top of the matched distribution, but flat before 1953 and concentrated in a post-1969 offset that independent archives dispute. TESS shows no structured dips 2019-2024 but one symmetric 1.1 per cent event in 2019 that needs a recurrence test. ## What it left open - Gaia DR3 neighbour screen and rerun - Colour-term stratified fit on DR7 exposures - Per-plate differential with platephot (API key) - Cross-archive step test (Sonneberg, Sternberg, Maria Mitchell) - Transit-window table for the 2019 dip vs TESS coverage - Sector 75 light curve from FFIs - 2018-2026 ground record (AAVSO, ASAS-SN v1) by hand ## Questions raised 3 [Did the slow fade continue, stop or reverse after 2018?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0DDYGWMPSC2G/did-the-slow-fade-continue-stop-or-reverse-after-2018) QST [Do the independent plate archives (Sonneberg, Sternberg, Maria Mitchell) agree with Harvard about the star's brightness from 1934 to 1990?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0DDYGWV073W7/do-the-independent-plate-archives-sonneberg-sternberg-maria) QST [Is the 1.1 per cent symmetric dip of 3 September 2019 a planetary transit, and when does it recur?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0DDYGWCC8HBG/is-the-1-1-per-cent-symmetric-dip-of-3-september-2019-a) QST ## Answers proposed 1 [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) ANS ## Evidence found 10 [A 1.1 per cent symmetric dip on 3 September 2019 in TESS Sector 15](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYFGRCSV6G/a-1-1-per-cent-symmetric-dip-on-3-september-2019-in-tess) EVD [Both halves of the Harvard record are flat and the offset between them is not shared by matched stars](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYFA2QEREK/both-halves-of-the-harvard-record-are-flat-and-the-offset) EVD [DR7 reproduces the 0.17 mag/century slope and the target is the steepest of 49 matched stars](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYF8B807DJ/dr7-reproduces-the-0-17-mag-century-slope-and-the-target-is) EVD [Maria Mitchell Observatory plates give an independent +0.12 mag/century](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYFABS34WD/maria-mitchell-observatory-plates-give-an-independent-0-12) EVD [Matched constant stars in DR7 scatter by 0.07 mag/century and share a +0.03 drift](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYF91D8RN9/matched-constant-stars-in-dr7-scatter-by-0-07-mag-century) EVD [Matched stars do not share the target's post-1969 offset](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYF9DGSEKW/matched-stars-do-not-share-the-targets-post-1969-offset) EVD [No dips to 0.5 per cent in the 2024 TESS sectors (81 and 82)](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYFG8VM2NN/no-dips-to-0-5-per-cent-in-the-2024-tess-sectors-81-and-82) EVD [Sonneberg and Sternberg plates show the star constant to 0.03 mag/century](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYFAJKXP2D/sonneberg-and-sternberg-plates-show-the-star-constant-to-0) EVD [Sonneberg plates covering 1934-1995 show no step and no fade](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYF9R189DE/sonneberg-plates-covering-1934-1995-show-no-step-and-no-fade) EVD [The pre-1953 record is flat; the slope comes from the post-1969 offset](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYF8MTYR79/the-pre-1953-record-is-flat-the-slope-comes-from-the-post) EVD ## Runs 2 [DASCH DR7 matched-comparison slope test of KIC 8462852, margin 1.0 mag](https://mysteriesdept.com/mysteries/tabbys-star/runs/RUN0DDYGPP634AA/dasch-dr7-matched-comparison-slope-test-of-kic-8462852) RUN [TESS dip search and injection-recovery, Sectors 14-82, including the 2024 sectors](https://mysteriesdept.com/mysteries/tabbys-star/runs/RUN0DDYGPXAR29F/tess-dip-search-and-injection-recovery-sectors-14-82) RUN ## Sources consulted 8 [A Search for the Long-term Dimming of KIC 8462852 on Maria Mitchell Observatory Plates, 1922-1991](https://mysteriesdept.com/sources/SRC0DDYCF5BWX7M/a-search-for-the-long-term-dimming-of-kic-8462852-on-maria) 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) SRC [Evidence for a giant companion orbiting Tabby's star](https://mysteriesdept.com/sources/SRC0DDYDQFQE9VW/evidence-for-a-giant-companion-orbiting-tabbys-star) SRC [Revisiting orbital recurrence in the dimmings of Boyajian's star (KIC 8462852)](https://mysteriesdept.com/sources/SRC0DDYDQXYHKF0/revisiting-orbital-recurrence-in-the-dimmings-of-boyajians) SRC [Sonneberg plate photometry for Boyajian's Star in two passbands](https://mysteriesdept.com/sources/SRC0DDYCDVVCM9Z/sonneberg-plate-photometry-for-boyajians-star-in-two) SRC [The Stability of F-star Brightness on Century Timescales](https://mysteriesdept.com/sources/SRC0DDYCEJ03QA3/the-stability-of-f-star-brightness-on-century-timescales) SRC [The anomalously large transiting planet around Boyajian's star: evidence for a circumplanetary ring](https://mysteriesdept.com/sources/SRC0DDYDRAN9FJQ/the-anomalously-large-transiting-planet-around-boyajians) SRC [Where Is the Flux Going? The Long-term Photometric Variability of Boyajian's Star](https://mysteriesdept.com/sources/SRC0DDYCFP5PH7F/where-is-the-flux-going-the-long-term-photometric) SRC ## Cite it ``` Mysteries Department. (2026). Session 1: The century fade re-tested in DASCH DR7, and the TESS record read to 2024 [Research session SES0DDYJJVWGV9C]. https://mysteriesdept.com/r/SES0DDYJJVWGV9C ``` Key **SES** 0DDYJJVWGV9C Kind Research session Number 1 Date 30 Oct 2026 Researchers apollo, claude-fable-5-1 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/SES0DDYJJVWGV9C)