The 24 solar terms

What the columns mean

id (string)

Stable row identifier, unchanged across versions

nam (int)

Gregorian year

thu_tu (int)

Ordinal of the solar term within the Gregorian year, counted from the first solar term falling in January

ten (string)

Solar term name

ten_en (string)

Solar term name in English

kinh_do_mat_troi (int)

Solar longitude at the start of the solar term, in degrees

ngay_bat_dau (string)

Gregorian date when the solar term begins, in YYYY-MM-DD format

y_nghia (string)

Astronomical or weather phenomenon marked by the solar term

nguon (string)

Kind of source for this row, one or more parts separated by semicolons, each being tinh-toan (computed by the engine), quy-uoc-truyen-thong, quy-uoc-he-hien-dai (convention of a tradition or of a modern system), van-ban (with the work after a colon) or bien-tap (with details); static details are also in the metadata nguon_chi_tiet, and the two largest datasets give them only there; which column belongs to which part is given by each column's loai_bang_chung in the metadata

ghi_chu (string)

Where the schools disagree on this row; empty when they do not

Release

Data release ID

2026.10.27-cd6fca71 · manifest.json

Dataset version

1.1.1

Dataset last changed

2026-09-30The date in the release ID is when the most recently changed dataset of the whole release changed. This dataset has not changed since the date above, so it keeps its version and is still part of this release.

Generated

2026-10-27 08:07 UTC

Rows

384 rows, 10 columns

Schema hash

b6c6891fe4a2ddee…Copysha256 of each column's name and type

Download this exact release

• 24-tiet-khi.csv · 50.2 KB · sha256 4cbd4d6e4d296ac6…Copy
• 24-tiet-khi.json · 119.3 KB · sha256 612c6b42a525af68…Copy
• 24-tiet-khi.meta.json · 31.9 KB · sha256 c2556d61a073dcf2…Copy

The “CSV for Excel” button at the top serves a copy with a BOM, so its hash differs from the CSV here.

Changes

Version 1.1.1 (2026-09-30), type documentation: The model profiles (solar terms 2.2.0, lunar calendar 1.2.0, Gua Qi 1.2.0) add kiem_dinh in a common layout: status, reference, sample size, tolerance, MAE, RMSE, median, P95, P99, maximum, bias, number of exceptions; each exception is listed in the companion file ngoai-le-doi-chieu.csv, and every check of every dataset in kiem-dinh.csv. The data is unchanged byte for byte. Metadata adds source_ids (source register nguon-thu-tich.csv), rule_ids (rule register quy-tac.json), danh_muc_tu_vung_nguon (the eight kinds of the nguon column with their English equivalents), a per-column epistemic_status and danh_muc_epistemic_status; the data is unchanged byte for byte.

Changelog of every dataset (CHANGELOG on GitHub)

Method

• Solar term moments tiet-khi-meeus-c25-bieu-kien-v2, engine version 2.2.0

Engine version of the release: 2.0.0. Full model profiles (mo-hinh.md)

Verification

• Solar term moments: tested against IMCCE (4,824 instants, at most 15 min off), U.S. Naval Observatory (804 instants, at most 15 min off).

Evidence types in this dataset, and how far each can be checked:

• A. Recomputable: an astronomical, calendrical or arithmetic algorithm yields the value, anyone with the algorithm can recompute it, and the engine has been checked against independent sources where they exist (model profile).
• C. Convention of a tradition or of a modern system: correct by that convention, neither true nor false in an empirical sense; where schools differ is recorded in the diem-bat-dong-giua-cac-phai dataset.

Provenance

Values computed by the site's engine with astronomical, calendrical or arithmetic algorithms; not copied from any printed table.

• A. Recomputable: nam, thu_tu, ten, ten_en, kinh_do_mat_troi, ngay_bat_dau
• C. Convention of a tradition or of a modern system: y_nghia

Cite this dataset

Nhật Nguyệt (2026). The 24 solar terms (version 1.1.1, data release 2026.10.27-cd6fca71) [Data set]. CC BY 4.0. DOI 10.5281/zenodo.23009396. https://nhatnguyet.org/en/bang/24-tiet-khiCopy

The concept DOI always resolves to the latest release. Zenodo mints a DOI for each release after it is published, and the next release records it in the manifest.

Licence and limitations

Released under CC BY 4.0: reuse commercially, adapt freely, attribution is all that is asked.

Source: Nhật Nguyệt (nhatnguyet.org), CC BY 4.0

This dataset records cultural and calendrical conventions, not scientific claims. It is suitable for cultural research, NLP, and calendar applications. It is not intended for predicting events, evaluating people, or making decisions that affect anyone.

Other reference tables

• The ten heavenly stems
• Compatibility matrix of the 12 earthly branches
• The twelve earthly branches
• The twelve day officers (Thap Nhi Truc)
• The 22 Major Arcana of the Tarot
• The 24 solar terms
• The 56 Minor Arcana cards
• Sexagenary cycle table (60 Hoa Giap)
• The 64 hexagrams of the I Ching
• The nine presiding stars (Cuu Dieu)
• Zodiac sign boundaries year by year, 1950 to 2050
• Retrieval evaluation set for Vietnamese folk belief and calendar
• Letter to number tables, Pythagorean and Chaldean
• Kua number and Bat Trach directions
• Where the schools disagree
• Auspicious hours across the sixty-day stem-branch cycle
• The sixty stem-branch pairs crossed: sounds, harmony, clash and element relation
• Questions and answers on Vietnamese offering rites
• Things to avoid and practical notes for Vietnamese offering rites
• Vietnamese festivals mapped to solar dates, 2026 to 2030
• Festivals and folk beliefs of the 54 ethnic groups of Vietnam
• Vietnamese festivals, seasonal feasts and public holidays
• Vietnamese ritual offerings
• Vietnamese lunisolar calendar, 1900 to 2100
• Types of Vietnamese offering rites
• Start moments of the 24 solar terms, 1900 to 2100
• Folk inauspicious days mapped onto solar dates, 2026 to 2035
• Vietnamese offering procedures
• Daily hexagram by the Gua Qi method, 1900 to 2100
• Tam Tai, Kim Lau and Hoang Oc by birth year and year in question
• Order of the sixty Gua Qi hexagrams
• Segments of the three Lo Ban rules
• Vietnamese offering prayers (văn cúng)

See every reference table