Primary observance
No selected discrete observance
The period and countdown layers remain active independently.
Proof of concept
Catholic Calendar
A deterministic, package-ready calendar engine for a curated Roman Catholic observance set. It resolves movable dates, liturgical and devotional periods, transfers, impediments and countdowns without an external API.
Model scopeCurated Roman calendar, with selected Marian observances and St Michael’s Lent
Interactive test
Calendar state tester
Select any supported civil date to inspect the three output layers, transfer decisions and the underlying movable-date calculations.
1 day until Our Lady of the Rosary
Active periods
No selected period
Countdown
1 day until Our Lady of the Rosary
Observed on 7 October 2026.
MemorialUpcoming
Calculation details
Easter Sunday5 April 2026
First Sunday of Advent29 November 2026
Next observed celebrationOur Lady of the Rosary · 7 October 2026
Nominal selections today0
Visual QA
Year overview
Review the modelled periods, curated celebrations and liturgical-rank semantics for the selected year.
Year
2026
Periods
Periods in this model
These are the liturgical and devotional periods currently exposed by the calendar engine for the selected year.
| Icon | Period | Kind | Start | End |
|---|---|---|---|---|
| Lent | Liturgical | 18 Feb 2026 | 02 Apr 2026 | |
| Holy Week | Liturgical | 29 Mar 2026 | 04 Apr 2026 | |
| Sacred Paschal Triduum | Liturgical | 02 Apr 2026 | 05 Apr 2026 | |
| Easter Time | Liturgical | 05 Apr 2026 | 24 May 2026 | |
| St Michael's Lent | Devotional | 15 Aug 2026 | 29 Sept 2026 | |
| Advent | Liturgical | 29 Nov 2026 | 24 Dec 2026 | |
| Christmas Time | Liturgical | 25 Dec 2026 | 10 Jan 2027 |
Ordinary Time is intentionally not modelled in this curated implementation.
Celebrations
Celebrations in this model
The curated observances for the selected year, including transferred, commemorated and impeded entries.
| Date | Icon | Celebration | Rank | Status | Nominal / reason |
|---|---|---|---|---|---|
| 01 Jan | Mary, the Holy Mother of GodSanta María, Madre de Dios | Solemnity | Observed | — | |
| 06 Jan | Epiphany of the LordEpifanía del Señor | Principal Day | Observed | — | |
| 11 Jan | Baptism of the LordBautismo del Señor | Feast | Observed | — | |
| 02 Feb | Presentation of the LordPresentación del Señor | Feast | Observed | — | |
| 11 Feb | Our Lady of LourdesNuestra Señora de Lourdes | Optional Memorial | Observed | — | |
| 18 Feb | Ash WednesdayMiércoles de Ceniza | Principal Day | Observed | — | |
| 19 Mar | Saint Joseph, Spouse of the Blessed Virgin MarySan José, esposo de la Bienaventurada Virgen María | Solemnity | Observed | — | |
| 25 Mar | Annunciation of the LordAnunciación del Señor | Solemnity | Observed | — | |
| 29 Mar | Palm Sunday of the Passion of the LordDomingo de Ramos de la Pasión del Señor | Principal Day | Observed | — | |
| 02 Apr | Holy ThursdayJueves Santo | Principal Day | Observed | — | |
| 03 Apr | Good Friday of the Passion of the LordViernes Santo de la Pasión del Señor | Principal Day | Observed | — | |
| 04 Apr | Holy SaturdaySábado Santo | Principal Day | Observed | — | |
| 05 Apr | Easter Sunday of the Resurrection of the LordDomingo de Pascua de la Resurrección del Señor | Principal Day | Observed | — | |
| 12 Apr | Divine Mercy SundayDomingo de la Divina Misericordia | Principal Day | Observed | — | |
| 16 Apr | Saint Bernadette SoubirousSanta Bernardita Soubirous | Optional Memorial | Observed | — | |
| 13 May | Our Lady of FatimaNuestra Señora de Fátima | Optional Memorial | Observed | — | |
| 14 May | Ascension of the LordAscensión del Señor | Principal Day | Observed | — | |
| 24 May | Pentecost SundayDomingo de Pentecostés | Principal Day | Observed | — | |
| 25 May | Blessed Virgin Mary, Mother of the ChurchBienaventurada Virgen María, Madre de la Iglesia | Memorial | Observed | — | |
| 31 May | Most Holy TrinitySantísima Trinidad | Solemnity | Observed | — | |
| 31 May | Visitation of the Blessed Virgin MaryVisitación de la Bienaventurada Virgen María | Feast | Impeded | Impeded by Sunday | |
| 04 Jun | Corpus ChristiSantísimo Cuerpo y Sangre de Cristo | Solemnity | Observed | — | |
| 12 Jun | Most Sacred Heart of JesusSagrado Corazón de Jesús | Solemnity | Observed | — | |
| 13 Jun | Immaculate Heart of the Blessed Virgin MaryInmaculado Corazón de la Bienaventurada Virgen María | Memorial | Observed | — | |
| 24 Jun | Nativity of Saint John the BaptistNatividad de San Juan Bautista | Solemnity | Observed | — | |
| 29 Jun | Saints Peter and Paul, ApostlesSantos Pedro y Pablo, apóstoles | Solemnity | Observed | — | |
| 11 Jul | Saint Benedict of NursiaSan Benito de Nursia | Memorial | Observed | — | |
| 16 Jul | Our Lady of Mount CarmelNuestra Señora del Carmen | Optional Memorial | Observed | — | |
| 06 Aug | Transfiguration of the LordTransfiguración del Señor | Feast | Observed | — | |
| 15 Aug | Assumption of the Blessed Virgin MaryAsunción de la Bienaventurada Virgen María | Solemnity | Observed | — | |
| 22 Aug | Queenship of the Blessed Virgin MaryBienaventurada Virgen María Reina | Memorial | Observed | — | |
| 08 Sept | Nativity of the Blessed Virgin MaryNatividad de la Santísima Virgen María | Feast | Observed | — | |
| 14 Sept | Exaltation of the Holy CrossExaltación de la Santa Cruz | Feast | Observed | — | |
| 15 Sept | Our Lady of SorrowsNuestra Señora de los Dolores | Memorial | Observed | — | |
| 29 Sept | Saints Michael, Gabriel and Raphael, ArchangelsSantos Miguel, Gabriel y Rafael, arcángeles | Feast | Observed | — | |
| 04 Oct | Saint Francis of AssisiSan Francisco de Asís | Memorial | Impeded | Impeded by Sunday | |
| 07 Oct | Our Lady of the RosaryNuestra Señora del Rosario | Memorial | Observed | — | |
| 01 Nov | All SaintsTodos los Santos | Solemnity | Observed | — | |
| 02 Nov | All SoulsConmemoración de todos los fieles difuntos | Commemoration | Observed | — | |
| 21 Nov | Presentation of the Blessed Virgin MaryPresentación de la Santísima Virgen María | Memorial | Observed | — | |
| 22 Nov | Our Lord Jesus Christ, King of the UniverseNuestro Señor Jesucristo, Rey del Universo | Solemnity | Observed | — | |
| 29 Nov | First Sunday of AdventPrimer Domingo de Adviento | Principal Day | Observed | — | |
| 08 Dec | Immaculate ConceptionInmaculada Concepción | Solemnity | Observed | — | |
| 10 Dec | Our Lady of LoretoNuestra Señora de Loreto | Optional Memorial | Observed | — | |
| 12 Dec | Our Lady of GuadalupeNuestra Señora de Guadalupe | Optional Memorial | Observed | — | |
| 25 Dec | ChristmasNavidad | Principal Day | Observed | — | |
| 27 Dec | Holy Family of Jesus, Mary and JosephSagrada Familia de Jesús, María y José | Feast | Observed | — |
Three layers
Independent outputs
Primary celebration, active periods and countdown state are computed separately so Advent, Lent or St Michael’s Lent never hides a feast.
Transfers
Nominal ≠ observed
Transfer and impediment metadata stay explicit. The tester can therefore show what normally belongs to a date without mislabelling it as the observed liturgy.
Integration
Prepared for packaging
Everything under lib/catholic-calendar is UI-agnostic TypeScript, ready to extract later for the Academic Website, Research Dashboard or other apps.
Release notes
v0.1.0-beta.1 “Crystal Falcon”
ReleasedCrystal Falcon refines the fixed two-item calendar display, preserves impeded same-day celebrations when space is available and streamlines the demonstration interface.
Calendar display
- Uses available composed-display space for impeded nominal celebrations without changing their canonical status or liturgical precedence.
- Keeps the display fixed at two items, ordered by primary observance, active periods, impeded nominal celebration and then countdown.
Interface
- Keeps the calendar control at the upper right, removes redundant date labels and shows the selected value directly in weekday format.
- Places periods above celebrations, right-aligns the Ordinary Time note with an icon, clarifies the calendar model scope and paginates Release Notes one release at a time.
Release preparation
- Carries Saint Francis of Assisi on 4 October with its General Roman Calendar memorial rank and an explicit display mapping.
- Bumps the application and package to v0.1.0-beta.1 and prepares the npm beta distribution channel.