ASCENSIONTHURSDAY Function (Gnumeric)

• Introduced: Gnumeric 1.9.15. The official 1.9.14-to-1.9.15 source diff adds the Christian-date implementation and registers all five named functions; the release notes identify the new calendar group. No exact release day is inferred from an archive timestamp.
• Documented support: Registered in the Christian Date Functions plugin for Gnumeric 1.12.62. No retirement is established.
• Last functioning version: Unverified; source support does not prove application execution.
• Evidence dates: The 1.12.62 source snapshot was retained October 13–14, 2026. The historical release diff and notes were retrieved October 15; calculations and this full guide were reviewed that day. No native Gnumeric or GUI test was run.

ASCENSIONTHURSDAY returns the Gregorian Thursday defined in Gnumeric’s Roman-rite calendar, exactly 39 elapsed calendar days after Easter Sunday. It does not move the observance to a locally chosen Sunday. An inclusive count that calls Easter day one reaches day 40 after 39 elapsed days; adding 40 would move the computed date one day late.

=ASCENSIONTHURSDAY([year])

The single numeric year argument is optional. With an explicit year, the shared helper converts it to an integer and applies Gnumeric’s year adjustment: 0–29 become 2000–2029, while 30–99 become 1930–1999. Thus 29 and 30 differ by nearly a century, not by one year. Use four-digit years for an auditable calendar. Negative integer years and years above 9956 return #NUM!.

The help states a nominal lower bound of 1582, but actual acceptance depends on date conventions and whether negative dates are enabled. The year-adjustment helper can reject years before the workbook’s 1900 or 1904 base. The modern worked years avoid this setting-dependent region. Blank and text coercions are unverified; an omitted argument is a deliberate separate operation.

Create AscensionYears with years 2024, 2025, 2026, 2027 and 2028 in A2:A6. Fill B2 =ASCENSIONTHURSDAY(A2) through B6. Expected dates are May 9, 2024; May 29, 2025; May 14, 2026; May 6, 2027; and May 25, 2028. Fill C2 =B2-EASTERSUNDAY(A2) downward. Every expected C result is 39. The weekday of these reference dates is Thursday, consistent with the exact function name.

These ISO dates make the expected calendar result unambiguous. A workbook can display a different localized date format without changing the underlying date. The table does not specify a date-system-dependent serial number.

For a planning sheet, put 2026 in B2, =EASTERSUNDAY(B2) in B3 and =ASCENSIONTHURSDAY(B2) in B4. B3 is April 5 and B4 May 14. B5 =B4-21 gives April 23, an arbitrary three-week preparation deadline. B6 =B4-B3+1 gives 40, the inclusive count; B7 =B4-B3 gives 39, the elapsed difference. Label the two counts explicitly.

On a copy, change B2 to 2027. Easter becomes March 28, the Thursday becomes May 6 and the preparation date becomes April 15. The inclusive and elapsed counts remain 40 and 39. This controlled year change catches both a hard-coded event date and an accidental 40-day arithmetic offset. The function produces a mathematical calendar anchor, not a guarantee that the date is the observed celebration or closure day in every locality.

The no-year helper reads the current system time, derives the calendar year and computes this specific holiday. It advances to next year only when this year’s holiday is strictly before the date being evaluated. Therefore the current holiday date itself is included in “next”; it does not automatically skip to next year on that day.

For a hypothetical evaluation date of 2026-05-13, =ASCENSIONTHURSDAY() has reference date 2026-05-14. On 2026-05-14, it still has that date. On 2026-05-15, it changes to 2027-05-06. These are simulated clock inputs to the source rule, not observations of today’s application output. The functions are registered as volatile; actual recalculation timing, timezone handling and saved-workbook caching were not tested.

The Thursday in the name is significant. If a local calendar transfers an observance, maintain that separate rule rather than modifying this function’s claimed meaning. A returned date can be correct under Gnumeric’s stated algorithm while still not matching the date your event organizer uses. Confirm the intended calendar before distributing a schedule.

If the output looks like an integer, inspect the cell’s date format before changing the formula. If a year is rejected, inspect the four-digit input and the workbook’s date conventions. Do not repair an unsupported date by silently changing the requested year. The shared implementation includes a correction for negative offsets crossing the fictitious February 29, 1900 serial-date gap; the simple date-offset worksheet identities above are claimed for the stated modern years, not every historical serial boundary.

Check exact function spelling and the Christian Date Functions plugin when resolving availability issues. This guide does not supply a tested plugin-installation workflow. Error displays for malformed expressions, locale-specific entry, external workbook import and extreme serial values are unverified. The explicit-year controls and hypothetical-clock controls serve different purposes and should be kept separate.

• Function-specific help
• Worksheet callback and exact calendar offset
• Shared Easter algorithm and serial conversion
• Gnumeric official function catalogue

EASTERSUNDAY, PENTECOSTSUNDAY, DATE.