# Cantus Organi

> Gregorian chant organ accompaniments from Nova Organi Harmonia ad Graduale Romanum (Lemmens Institute, Mechelen: H. Dessain, 1942), with 1962 calendar pages and Ordinary Form chant assignments based on the Graduale Romanum (1974).

The site contains scanned score systems and, where available, volunteer transcriptions. It provides Mass Propers, the Kyriale, hymns and Vespers. Chant text is included in expandable Latin text sections where a source is available. Scores can be exported as PDFs in the browser; use the HTML page as the citation URL.

## Find music

- [Search](https://cantusorgani.org/search/): Search titles, Latin opening words and chant text.
- [Extraordinary Form (1962) Calendar](https://cantusorgani.org/calendar/): Find the Mass and Vespers for a date under the 1962 rubrics.
- [Ordinary Form Calendar](https://cantusorgani.org/calendar/ordinary-form/): Find the Ordinary Form celebration, cycles and Graduale Romanum (1974) chants for a date; follow available NOH accompaniments.
- [Ordinary Form accompaniments](https://cantusorgani.org/ordinary-form/): Static pages assemble the available NOH music for each Ordinary Form occasion. Chant assignments come from the pinned jgabc source and reviewed overrides; a chant may have no NOH accompaniment.
- [Proper of Time](https://cantusorgani.org/proper-of-time/): Sundays and movable observances.
- [Proper of Saints](https://cantusorgani.org/proper-of-saints/): Saints and fixed feasts.
- [Common](https://cantusorgani.org/commune/): Common Masses.
- [Kyriale](https://cantusorgani.org/kyriale/): Ordinaries of the Mass and related chants.
- [Hymns](https://cantusorgani.org/hymns/): The hymns in book VII, with chant references.
- [Vespers](https://cantusorgani.org/vespers/): Dated offices in the order sung.
- [Sitemap](https://cantusorgani.org/sitemap.xml): Current indexable canonical page URLs.

## Cite music and distinguish page types

Piece pages at /piece/<slug>/ identify the book section, volume and printed page numbers. Movement anchors such as #introit link to a specific part. Kyriale Mass pages at /kyriale/<mass>/ are their preferred addresses; redirected piece URLs are aliases.

An evergreen Vesperale piece page shows the book's music section and links to dates when it is used. A dated /vespers/<date>/ page assembles the full II Vespers for that date. /vespers/<date>/i/ gives I Vespers of the named feast, with the actual evening stated on the page. These are distinct from the source book section. Cite the date and I or II Vespers when citing a dated order. Available dated pages cover the site's published generation window; the current sitemap and Vespers index list them.

Suggested citation: “Nova Organi Harmonia, [volume], [printed pages], [piece or office title], [movement if applicable], Cantus Organi, [canonical page URL with movement anchor if applicable].” For chant melody or text, cite the linked GregoBase record as well. Printed book page numbers differ from PDF scan page numbers.

## Sources, licensing and editorial status

- [About and source attributions](https://cantusorgani.org/about/#sources): The 1942 NOH page images and their slices are public domain. Published GregoBase chant transcriptions are CC0; transcriptions flagged copyrighted are linked rather than reproduced. Other contributions have their own licensing; the whole website should not be described as uniformly public domain.
- [Typeset music](https://cantusorgani.org/about/#typeset): Volunteer transcriptions are marked with their proofreading status. The scan is the reference when a transcription differs.
- [Limits](https://cantusorgani.org/about/#limits): Calendar scope, Ordinary Form source assignments, missing accompaniments, unprinted tones and uncertain catalogue records.
- [Corrections log](https://cantusorgani.org/corrections/log/): Published catalogue corrections.
- [Report an error](https://cantusorgani.org/corrections/): Report a discrepancy using its linked piece or part.

This is a navigation and citation guide, not a promise of complete liturgical coverage or an indexing requirement. robots.txt provides the site's crawler policy.

The Ordinary Form calendar assigns chants from the 1974 Graduale Romanum; it does not imply that those chants are printed in NOH. Missing NOH accompaniments and unmapped assignments are identified on the page.