The purpose of this Specification is to establish a Calendar for
Republic of Terra that allows for counting, naming and
identification of days and years in a way that:
• accurately follows the sacred astronomical cycles of our planet,
tying our identification of days and years to our place in the
• is consistent with mathematical principles and convenient for
• is internally consistent and free of historical idiosyncrasies;
• uses a time reference point that was a real event marking some
very significant achievement for all humankind, rather than an
invented zero point serving to underscore a particular doctrine;
• is suitable for both global and local applications;
• makes use of modern science and provides the level of accuracy
meeting the strict time precision demands of modern electronic
computer, communication and information processing systems;
• is based on sound mathematics and astronomy, rather than an edict
of an authority figure from the dark ages.
Local solar day
Period of time starting at midnight (lower
of the Sun) lasting until the next midnight. Can be
established either by direct astronomical observation
or by computation from UT and the time zone offset.
86400 SI seconds.
MJD (Modified Julian Day)
As used in this Specification, an
MJD is an integer identifying a day in a calendar-neutral manner. This Specification uses MJDs to
identify local solar days, days of UT, and mathematical
days of TAI. The specific mapping between days and
integers assigned to them is historical and corresponds
to that used by the Smithsonian Astrophysical
Observatory (SAO) to track the first Soviet artificial
Point of Ostara
The instant in the tropical year at which the Sun
crosses the Earth’s equator from south to north. Note
that the point of Ostara is an infinitesimal point in
time, rather than a day or any other extended interval.
The duration of 9192631770 periods of the radiation
corresponding to the transition between the two
hyperfine levels of the ground state of the cesium 133
Temps Atomique International (International Atomic
Time), an international time standard that counts SI
seconds with the highest accuracy possible with current
technology, independent of any astronomical cycle or calendar.
A complete cycle of seasons caused by Earth’s
and manifested in the point at which sunlight strikes
the Earth at a right angle moving between the tropics.
Universal Time, the generic term for time systems
anchored to Earth’s rotation and solar days, using the
Greenwich meridian as the reference point. Also called
GMT (Greenwich Mean Time).
An attempt, codified by international standards, to
reconcile TAI with UT. In its present form defined by
CCIR Recommendation 460 and its successors, it is a
scheme that gives an alternate name to each TAI second
that is (almost) usable as a form of UT.
UTCA (UTC Angle)
The turning angle of a dial clock
synchronized to UTC expressed in seconds. UTCA is
identical with UTC except around leap seconds.
3. Demarkation, counting and identification of years
3.1. Demarkation of years
Throughout the ages people have observed the passing of years by the
cycle of seasons. Therefore, the common notion of a year corresponds
to the astronomical definition of a tropical year given in Clause 2.
In the Republic of Terra Calendar a year shall mean a tropical year,
and each new year shall be considered to begin at the point of
3.2. Numbering of years
The Republic of Terra Calendar shall count years from man’s first
trip into outer space on humankind’s own initiative and technology,
i.e., the flight of Soviet cosmonaut Yuriy Gagarin. Years shall be
identified by cardinal numbers. The year in which Gagarin’s flight
took place (the 12th of April of 1961 by the calendar in effect in
the Soviet Union at the time of the event) shall be called year 0 of
(Since RT Calendar years begin at the point of Ostara,
year 0 is the year that began on Ostara before Gagarin’s flight and
ended on the following Ostara.)
The following year shall be called
year 1 of Space Era, followed by year 2 and so forth. The year
preceding year 0 of Space Era shall be called year -1 before Space
Era. The year before it shall be called year -2 before Space Era and
3.2.1. Standard format for year numbers
The preferred way to write the number of year n of Space Era is SE
n. The preferred way to write the number of year -n (before Space
Era) is BSE n. However, since RT Calendar year numbers are ordinary
integers, they can also be written as n and -n, respectively, where
it is more convenient, e.g., in computations.
3.3. Reckoning of years
The Republic of Terra Calendar Keeper (see Annex A) shall announce
the starting time of every RT Calendar year (point of Ostara) in
seconds of International Atomic Time (TAI) via the Calendar Master
File. Each year shall be defined to begin on a certain TAI second
and last until the TAI second that starts the next year. TAI is used
instead of UT or other time systems based on solar days since the
cycle of tropical years is completely independent of other
astronomical cycles, such as that of solar days, and thus should be
reckoned by absolute time. The length of each year is thus an
integral number of seconds, rather than days.
The Republic of Terra Calendar Keeper is responsible for announcing
the starting time of every year at least 180 days in advance. The
Calendar Keeper should strive for one SI second precision, i.e.,
within one SI second of the actual astronomical point of Ostara, but
the minimum required precision is that the error does not exceed 120
Since year lengths are measured in seconds rather than days and the
start of each year is anchored to actual astronomical observation,
no leap year scheme is used or needed.
3.3.1. Calendar Master File
The Calendar Master File (CMF) shall be produced and published by
the Republic of Terra Calendar Keeper and shall indicate the TAI
start time of every RT Calendar year. Annex B specifies the format
of CMFs and other calendar data files.
The RT Calendar Keeper is required to publish a Calendar Master File
or a set of CMFs covering all years from SE 0 through the present,
as well as the next year if it is expected to begin in 180 days or
The RT Calendar Keeper may publish proleptic calendar data files for
some periods before Space Era, but is not required to. Such files
will generally be produced by historians to aid in the conversion of
historical dates to the RT Calendar. The Republic of Terra Calendar
Keeper’s Office shall provide an online electronic repository for
these files so that once a correct proleptic calendar data file has
been created for some period by some historian, this work will never
need to be duplicated by others.
3.3.2. Corrections to CMF data
If a previously published starting time of a year prior to SE 44 is
found to be in error, it may always be amended by publishing a
corrected CMF. For years from SE 44 onward, once a year has started,
the starting time published for it by the RT Calendar Keeper becomes
the official starting time of that year for civil purposes, even if
it is not astronomically exact.
CMF data for years that have not yet started are predictions. These
predictions may be changed in favour of more accurate ones until 180
days prior to the start of the new year. After that point the
published time becomes final and official for civil purposes as
4. Intercalation of days and years
One of the main functions of any calendar is to assign dates to
days. The difference between a day and a date must be clearly
understood. The term “day” commonly refers to a local solar day as
defined in Clause 2, and that shall be the meaning of the word “day”
in this Specification. A calendar date, however, identifies a
certain point in the year, i.e., a certain point in the annual
seasonal cycle and (approximately) in Earth’s orbit around the Sun
(approximately rather than exactly due to precession of equinoxes).
Days are local, but dates are global.
Since days and years are dictated by two different and completely
independent astronomical cycles (Earth’s rotation for days and
Earth’s orbit around the Sun and precession for years), it is
meaningless to try divide the year into days, and days and dates do
not exactly coincide. Rather than impose some arbitrary and
ultimately unjustified scheme for dividing years into days, this
Specification addresses the problem and specifies a standard
approximation scheme for mapping days to dates that provides the
highest possible accuracy, with the error never exceeding 12 hours.
4.1. Definition of dates
Each RT Calendar year shall be divided into mathematical days of
86400 SI seconds each (bearing no relation to solar days).
Mathematical day of year (DOY) 0 shall begin at the point of Ostara.
Since the length of one tropical year equals approximately 365.25
mathematical days, each RT Calendar year shall consist of 365 full
DOYs and one short DOY.
DOYs shall be reckoned by TAI, rather than
UTC or any other time system adjusted for Earth’s rotation, since
DOYs are mathematical days of the year completely independent of
local solar days and Earth rotation. Each DOY shall be assigned a
date name as specified in Clause 5.
4.2. Mapping of local solar days to dates
Local solar days may be identified by calendar-neutral flat integers
called MJDs. This subclause specifies the algorithm for mapping an
MJD to an RT Calendar date. The mapping function is dependent on the
time zone, thus a given date may be mapped to different MJDs in
different time zones. (Note that since an MJD as used here
identifies a local solar day and each time zone has its own local
solar days, each time zone has its own MJDs.)
To establish the mapping the following procedure must be followed
each year in each time zone:
1. Take the year starting time from the Calendar Master File.
2. Convert it from TAI to UT per UTC standard.
3. Convert from UT to local time by adding or subtracting the
appropriate time zone offset. This step will yield the MJD and time
of Ostara in the local time zone.
4. If the local time of Ostara is between 0:00:00 and 11:59:59, the
local MJD on which Ostara falls shall be mapped to DOY 0 of the new
year. If the local time of Ostara is between 12:00:00 and 23:59:59,
DOY 0 of the new year shall be mapped to the next local MJD.
This algorithm guarantees that year dates and local solar days
mapped to them will always overlap by at least 12 hours.
Once a given MJD in a given time zone has been mapped to DOY 0,
succeeding MJDs shall be mapped to succeeding DOYs until next Ostara
when an MJD is mapped to DOY 0 of the next year. 365 or 366 MJDs
will be mapped in each time zone to a given RT Calendar year
depending on the time zone and the times on which the two succeeding
Ostara points fall. Since each RT Calendar year consists of 366
mathematical DOYs (the last one short), date names will be available
for all these MJDs.
5. Naming of dates
Subclause 4.1 identifies 366 distinct dates in each RT Calendar
year, numbered 0 through 365 as days of the year (DOY). This clause
specifies names for these dates in the traditional month and day
The first 360 DOYs shall be divided into 12 months of 30 days each,
similar to ancient Babylonian and French Revolutionary calendars.
The last 6 dates do not belong to any month and are identified only
by their DOY numbers. In every locality (time zone) the last 5 or 6
days will be mapped to these dates. These days shall be holidays on
which a pre-Ostara festival shall be held, and the corresponding
dates shall be considered festival dates.
Months and days of each month shall be numbered from 0. Months may
be given different names in different languages, but for
international communication in ASCII two alternatives are specified:
ASCIIfied ancient Akkadian and French Revolutionary calendar month
names. While neither the ancient Mesopotamian nor the French
Revolutionary calendar is identical with the Republic of Terra
Calendar, their months are compatible since all calendars in
question begin the first month of the year on an equinox (Ostara or
Roman month names may not be used with the Republic of Terra
Calendar, however, since Roman months do not correspond to RT
Calendar months and trying to reuse Roman month names for completely
different months would produce extreme confusion, but no useful
The standard month names are:
5.1. Standard date format
The standard format for writing Republic of Terra Calendar dates is:
<year> Mon dd
where <year> is the year in the preferred notation of paragraph
3.2.1, Mon is the three-letter abbreviation for the month and dd is
the day number in decimal. For example, day 3 of Thermidor of year
42 of Space Era shall be written as:
SE 42 Thr 3
For festival dates the three-letter month abbreviation shall be Fes
and the day number shall be DOY-360.
6. Practical applications
6.1. Local applications
6.1.1. Operation of clocks
It is expected that most clocks and other devices and systems that
display time and date will continue to show the current local time
and corresponding date as they did prior to the adoption of this new
Calendar. Those devices that can only display time and not the date
will require no modification. Devices that track or display dates
will need to be changed to the new Calendar and date format.
The Republic of Terra Calendar is more complex than most previous
calendars in that the mapping from an MJD to a date is not a fixed
formula, but depends on the actual astronomical observation of
Ostara published via the Calendar Master File and on the time zone.
Most clocks are set manually by their human users and have no
connection to global communication networks for time
The new Calendar’s complexities will not present
any great difficulties for such clocks since their users can simply
set the correct date. Since RT Calendar uses no leap year scheme,
those clocks won’t be able to decide automatically whether to jump
to DOY 0 of the next year after DOY 364 or 365, but needing manual
attention once a year should not be an unreasonable burden.
6.1.2. Printing of wall calendars
Since the mapping between MJDs, from which the days of the week are
derived, and RT Calendar dates differs with the time zone, different
versions of wall calendars will need to be printed for different
time zones. However, since there are only two possible MJDs to which
day 0 of each year can be mapped, only two versions of the wall
calendar will need to be printed each year, each serving one half of
the world’s time zones.
(More versions may be printed, though, if
other time zone-dependent information is included, such as exact
times of various astronomical phenomena.)
6.2. Time signal distribution services
Point of Ostara information from the Republic of Terra Calendar
Master File should be distributed by time signal services similar to
how TAI, UTC and leap second information are distributed now. With
this information radio-synchronized clocks can be built that always
display accurate RT Calendar date and time; their firmware will need
to implement algorithms prescribed in this Specification.
6.3. Computer clocks
It is expected that simple computer clocks will be free-running and
to be set to the correct date and time by their users as described
6.1. More advanced computer systems will be more likely to have
highly accurate clocks synchronised with TAI or UTC over
communication networks, and store local copies of the Calendar
Master File in their file system, updated over networks.
configuration such systems will be able to compute the correct
Republic of Terra Calendar date and time for any time zone by
implementing algorithms prescribed in this Specification.
6.4. Global applications
6.4.1. Recording of important dates
There exists an obvious need to record the dates of major events
that have global and lasting significance, such as birthdays,
marriages, signing of treaties and declarations and major
accomplishments. The date recorded for each such event shall be the
true global date on which the event happened, in the definition of
subclause 4.1, rather than the date mapped to the local solar day
(as would be displayed on a wall calendar).
One difficulty arises in how would people know the correct global
date if all wall clocks and calendars are synchronized with local
solar days rather than global dates. The solution lies in informing
people of the exact difference between local solar days in their
locality and global dates, based on the algorithm specified in
Computer systems with advanced time keeping functions
shall have a capability to display the exact overlap between local
solar days and global dates in a message such as “global date equals
local calendar date from midnight until 15:47:32; after 15:47:32
increment the local date by one to obtain the global date” or
“global date equals local calendar date from 6:39:13 until midnight;
before 6:39:13 decrement the local date by one to obtain the global
If less sophisticated wall clocks are used, this information
may be printed or written on a piece of paper placed next to the
6.4.2. Global date-time specifications
In environments such as international radio and Internet
communications or flight operations there is a need for precise and
unambiguous date-time specifications valid on the entire globe.
paragraph prescribes the form of Republic of Terra Global Date-Time
(RTGDT) specifications to be used for such applications in the
Republic of Terra. The RTGDT time shall be UTCA (defined in Clause
2) and the semantics of the RTGDT date are given below.
The RTGDT date is almost the same as the true global date (in the
definition of subclause 4.1) except that it is reckoned by UTCA
rather than TAI. Specifically, the starting time of the year from
the Calendar Master File is converted from TAI to UTCA, and each
RTGDT DOY from Nis 0 onward corresponds to 86400 seconds of UTCA.
The RTGDT date will almost always be exactly equal to the true
global date except when the day boundary is off by a second or two
because of leap seconds introduced during the year.
7. Conversion from other calendars to RT Calendar
7.1. Conversion of local dates
To convert a local date from another calendar to the RT Calendar,
first convert it to MJD by the other calendar’s formula or algorithm
and then convert the MJD to the RT Calendar date by the mapping
prescribed in subclause 4.2.
7.2. Conversion of global dates
Dates of historical events of global and lasting significance shall
be converted to RT Calendar global dates as described in subclause
4.1 and paragraph 6.4.1. Since all previous calendars had the local
solar day rather than the global year as their fundamental unit, the
conversion requires additional information beyond the date in the
old calendar, namely the time and the time zone.
The conversion consists of fixing the moment in time when the
historical event happened and determining what global date it would
have fallen on if the RT Calendar were in effect then. The following
algorithm or functional equivalent shall be used:
1. Convert the old date to MJD by the old calendar’s formula or
algorithm. This step will yield the local MJD and time of the event.
2. Convert the local MJD and time specification to UT by adding or
subtracting the appropriate time zone offset (make sure to use the
offset in effect at the time of the historical event).
3. Convert to TAI if possible (see Annex D).
4. Convert to RT Calendar year and time within the year via the
Calendar Master File.
5. Divide the time within the year by 86400 seconds. The integer
quotient will be the date of the event in DOY form.
8. Other specifications
8.1. Daylight saving time
Use of daylight saving time in the Republic of Terra is prohibited
by this Specification. The mapping of local solar days to global
dates depends on each time zone’s UT offset, which must remain
If adjustment is desired to make more efficient use of sunlight and
reduce the need for artificial lighting, work schedules may be
adjusted instead of changing clocks.
Practice of numerology on Republic of Terra Calendar dates is
strictly and expressly prohibited by this Specification. The numbers
of years, months and days are objective, scientifically based
mathematical statements about the identity of a given year, month or
day, and do not carry any other associations.
Annex A (normative)
Republic of Terra Calendar Keeper’s Office
The Republic of Terra shall have an Office of the Calendar Keeper.
The RT Calendar Keeper shall be a High Priest trained and competent
in astronomy, mathematics and computer science. The Calendar Keeper
shall be responsible for watching our planet’s astronomical cycles
and ensuring that our Calendar accurately matches the sacred cycles
of nature and our place in the cosmos.
The Calendar Keeper shall determine the official precise time of the
Ostara and publish it via the Calendar Master File as described in
Annex B (normative)
Calendar data file format
This Annex defines the format of Calendar Master Files and other
data files giving the times of significant astronomical or
A calendar data file is a machine-readable ASCII text file
containing time point definitions. Each line in a calendar data file
is either a time point definition or a comment line. A comment line
is an empty line, a line consisting entirely of white space, or a
line beginning with a semicolon (‘;’).
Each time point definition has the following format:
<year> <point> <time>
<year> is the RT Calendar year number in the format recommended by
<point> is a keyword (case-insensitive) identifying the point
in the year that is being described:
START Beginning of the year (point of Ostara)
SUMMER Beginning of astronomical summer
AUTUMN Beginning of astronomical autumn
WINTER Beginning of astronomical winter
Other keywords may be defined in the future, either in future
revisions of this Specification or in other specifications,
therefore programs parsing calendar data files must be prepared to
deal with unknown time point definitions.
<time> gives the time of the instant being described in TAI or UT
with one second precision. A TAI <time> has the format:
A UT <time> has the format:
where mjd, hh, mm and ss are all decimal integers. hh, mm and ss
shall be written with 2 digits each, no restriction is imposed on
the number of digits for mjd.
Annex C (informative)
Meaning of TAI MJD
Normal MJDs are local solar days and are timed by Earth’s rotation.
TAI MJDs, however, are mathematical days. TAI is independent of
Earth’s rotation and local solar days, and TAI MJDs are merely a
Since TAI is an absolute time system not
anchored to any astronomical cycle, it is difficult to establish a
reference point for it. When TAI was adopted as a standard, it was
chosen to express it in the form of days, hours, minutes and seconds
like ordinary time based on local solar days, with the understanding
that TAI days are in fact mathematical days rather than local solar
The TAI reference point was defined at MJD 36204 (January 1, 1958 by
the calendar in effect at the time), namely TAI MJD 36204 was
defined to coincide with UT MJD 36204.
Annex D (normative)
Proleptic use of RT Calendar before TAI
This Specification is specifically intended so that the Republic of
Terra Calendar may be used not only in the present and future, but
also proleptically to date events that happened long before its
introduction. However, this Specification stipulates the use of TAI
for demarkation of years and dates, and TAI is only defined back to
MJD 36204 (in late BSE 4).
Rather than invent a “proleptic TAI” that would have very little
other use, it is permitted to use other time systems, such as UT or
Ephemeris Time (ET), instead of TAI for years before Space Era.
Annex E (informative)
Specification revision history
Revision Date Author Notes
1.0 SE 43 Add 28 Michael Sokolov Original version.
2.0 SE 44 Ulu 3 Michael Sokolov Changed the way the RT
Calendar is used with
UTC (par. 6.4.2),
specified how to use
the Calendar before
TAI, added subcl. 8.2,
and minor changes.
2.1 SE 44 Ulu 19 Michael Sokolov Clarified our
definition of MJD,
minor language changes
throughout the spec for
more correct use of the
term UTC, added UTCA.