The Laodicean Times
How The Jewish Calendar is Calculated
HISTORY
In biblical days, time was measured by observation of
both the sun's pattern of motion and the lunar
phases. The solar motion served to establish the
duration of the year while the waxing and waning of
the moon was a practical way to subdivide the year
into months. But, unfortunately, the solar year and
the lunar cycles are not synchronized. While the
present calendar (Gregorian) had its roots in the
lunar cycle as evidenced by the length of the months
and even the word "month" itself, it was adjusted to
the solar year in order to maintain the seasonal
references - its relation to the lunar phases was
eventually abandoned. The Jewish calendar, on the
other hand, maintains both the lunar and solar
relationship and also adjusts for certain religious
requirements. The establishment of such a calendar
was a remarkable accomplishment for a people living
more than 2,000 years ago.
Today it is known that one solar year is
approximately 365 days, 5 hours, 48 minutes and 46
seconds. The lunar cycle is approximately 29 days,
12 hours, 44 minutes and 3 1/3 seconds (actually
2.841 seconds by current measurement). Therefore,
twelve lunar months are 354 days, 8 hours, 48
minutes and 40 seconds, which falls short of a
solar year by almost eleven days (10 days, 21
hours and 6 seconds). This difference will play an
important role in the calendar calculations.
Of course, a practical calendar must have a
whole number of days in each month. Since the
lunar month is very nearly 29 1/2 days, a calendar
that has twelve months alternating between 29 and
30 days (averaging 29 1/2) would essentially
follow the lunar cycle. In fact, this sequence
forms the basis for the Jewish calendar. Such a
year would have a length of 354 days, short by
about eleven days from the solar year. If this
were left uncorrected the seasons would quickly
drift from their relationship to the months. However, many Jewish
festivals are related to agricultural events and
must occur during specific seasons.
During the period of the Second Temple (built
between 519 and 516 B.C.) and for three centuries
after its destruction, a council of the Sanhedrin
(the governing body of the time) decreed when the
new months would begin and when adjustment was
needed to compensate for the seasonal shifts. The start of each
month was established by observing the arrival
of the new moon. The council would meet
on the thirtieth day of the month to hear the
testimony of "two trustworthy witnesses" as to
whether they observed
the new crescent moon on that day. If
they had, that day was declared the first of the
new month. If they did not, then the next day was
declared the first of the new month.
Once the council had made their declaration the
new month was announced by means of fire signals
to inform the communities outside of Jerusalem.
Distant villages which could not always receive
prompt notice would celebrate the new moon for two
days to be sure they had included the right day.
The council was empowered to compensate for the
solar and lunar differences by mandating that a
"leap month" be inserted in the calendar every
second or third year as the eleven day difference
accumulated. They allowed for some flexibility,
considering astronomical facts as well as
religious and agricultural requirements. They
observed the state of the crops, considered the
need to make the Passover journey by way of muddy
roads and tried to insert the leap month in an
advantageous way.
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PRESENT JEWISH
CALENDAR
In 432 B.C. the Athenian astronomer Meton reformed
the Athenian calendar based on an approximate
relationship between the solar and lunar cycles.
He had observed that every nineteen years the
occurrences of the new and full moons returned to
the same time with respect to the solar cycle.
This pattern is known as the Metonic cycle.
Actually, in nineteen years the annual difference
(10 days, 21 hours and 6 seconds) accumulates to
206 days, 15 hours, 1 minute and 54 seconds. This
accumulation is equal (within two hours) to seven
lunar months (which come to 206 days, 17 hours, 8
minutes and 23 1/3 seconds). So if seven lunar
months were added over a nineteen year period the
lunar and solar cycles could be more or less
maintained in synchronization.
For the early Jews the day began and ended at
sundown rather than at midnight. (Genesis says,
"... and there was evening, and there was morning,
one day"). For purposes of the Jewish calendar it
still does. The new day (and hence the start of
the Sabbath or a holiday) begins at sundown.
However, for calendar calculations the day is
considered to begin and end at 6 o'clock in the
evening, Jerusalem time. The hour of 6 pm is
therefore considered hour "zero". The hour was
subdivided into 1080 "parts". So a part was 3 1/3
seconds and there were 18 parts in a minute. Each
part was divided into 76 "moments". So there were
22.8 moments in a second. Many texts still refer
to the use of "parts" but "seconds" will be used
for the calculations described below.
The chronology of the bible was calculated
directly from the bible text and is given in the
Talmud (a collection of Rabbinic writing created
during the Hellenistic Age). The rabbis derived
the following chronology:
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Year
|
Event
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Comment
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1
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Adam
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The Creation
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1057
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Noah
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1056 years from Adam to Noah
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1949
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Abraham
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892 years from Noah to Abraham
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2049
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Isaac
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100 years from Abraham to Isaac
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2239
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Entrance into Egypt
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190 years from Isaac to Egypt
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2449
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The Exodus
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210 years from Egypt to Exodus
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2929
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Dedication of First Temple
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480 years from Exodus to 1st Temple
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3339
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Destruction of First Temple
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410 years duration of 1st Temple
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3409
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Return to Israel
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70 years of Babylonian Exile
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3829
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Destruction of Second Temple
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420 years duration of 2nd Temple
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| Ancient names for the
months are mentioned in Deuteronomy and Kings I but
little else is known about the names of the months
until the period of the Kings. At that time there
was a reformation of the calendar and the months
were referred to by their ordinal numbers (first,
second, third month, etc.) and the start of the year
was changed to the spring. By the end of the period
of the Second Temple the months had again received
names which are used today. The names are Babylonian
and were probably adopted shortly after the
Babylonian Exile.
The Bible refers to Nisan, the month of spring
and Passover, as the first month. Ancient writings
actually refer to four different new years: Nisan
1 for Kings and festivals, Elul 1 for tithing of
animals, Tishri 1 for the calendar and Shevat 1 or
15 for trees. Tishri
1 is now observed as the beginning of the year.
There are numerous transliterations for Hebrew
words. The spellings used here are those used in
The Encyclopaedia Judaica.
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THE CALENDAR
CALCULATIONS
The rules for
the present Jewish calendar system are
believed to have been published by the patriarch
Hillel II in the year 358, the Jewish year 4119.
Rather than having the Sanhedrin determine when to
add the leap month (Adar II), it was decided to
introduce it exactly seven times every nineteen
years. Furthermore, it was established that leap
years would be the 3rd, 6th, 8th, 11th, 14th, 17th
and 19th years of the cycle. Adar II, a 29-day
month, would be added after Adar. Adar would be
increased by one day to 30 days in a leap year
giving it 30 days more than the ordinary year.
Thus the Calendar would appear as shown in Table
1.
Table 1
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Basis of Jewish Calendar
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Tishri 30 days
Heshvan 29 days
Kislev 30 days
Tevet 29 days
Shevat 30 days
Adar 29 days (30 on a leap year)
Adar II 29 days (inserted 7 times every 19 years)
Nisan 30 days
Iyyar 29 days
Sivan 30 days
Tammuz 29 days
Av 30 days
Elul 29 days
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Such a calendar would be reasonably accurate, with months
based on the lunar cycle and with a correction for
the solar year. To understand the other adjustments
however, it is necessary to consider the Jewish
holidays. The following table shows the traditional
Jewish holidays.
Table 2
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Jewish Holidays
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Hebrew Name Description Month Note
================================================================
Rosh Hashanah New Year Tishri 1 & 2
Tzom Gedaliah Fast of Gedaliah Tishri 3 1
Yom Kippur Day of Atonement Tishri 10
Succoth Tabernacles Tishri 15-21
Hoshanah Rabba Festival of Willows Tishri 21
Sh'mini Atzeret Closing Holiday Tishri 22
Simchat Torah Rejoicing of Torah Tishri 23
Hanukkah Festival of Lights Kislev 25 (8 days)
Tzom Tevet Siege of Jerusalem Tevet 10
Tu B'Shevat New Year for Trees Shevat 15
Ta'anit Esther Fast of Esther Adar 13 2,3
Purim Feast of Lots Adar 14 3
Ta'anit Bechorim Fast of First Born Nisan 14 2
Pesach Passover Nisan 15-22
Yom Hashoah Holocaust Commem. Nisan 27 4
Yom Haatzmaut Israel Ind. Day Iyyar 5 2,5
Lag B'Omer 33rd Day of Omer Iyyar 18
Shavuot Festival of Weeks Sivan 6 & 7
Tzom Tammuz Fast of Tammuz Tammuz 17 1
Tisha B'Av Destr. of Temple Av 9 1
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Notes 1. If date occurs on Sabbath, it takes place
on following day, Sunday. 2. If date occurs on
Sabbath, it takes place on preceding Thursday. 3.
Adar II if leap year. 4. Established 1951. 5.
Established 1949. Two problems exist with respect to
these holidays. First, since Yom Kippur (Tishri 10)
is a major fast day, it is undesirable for it to
fall on a Friday or Sunday, adjacent to the Sabbath,
because of limitations that would be imposed on the
preparation for (or breaking of) the fast. Second,
Hoshanah Rabba (Tishri 21) should not fall on a
Saturday since the Sabbath laws would interfere with
certain rituals. Both of these holidays occur in the
first month, Tishri, so it can be said that Rosh
Hashanah (Tishri 1, the New Year's Day) must not
fall on a Wednesday, Friday, or Sunday.
The Jewish calendar calculation is based on the
following three steps. First, the new moon date
and time (called the Molad) is calculated and the
start of each month is first targeted for that
date. Second, the day of Rosh Hashanah is adjusted
according to rules discussed below. Third, a leap
month is periodically introduced to maintain
synchronization with the solar year. However, the
processes of adjusting the occurrence of Rosh
Hashanah is somewhat complex. It is accomplished
by lengthening or shortening the prior year by one
day. The month of Heshvan may be lengthened to 30
days and Kislev may be shortened to 29. When
Heshvan is lengthened the year is called "full"
and when Kislev is shortened the year is called
"deficient". Otherwise it is called "normal". This
means that three "types" of regular years can
exist having totals of 353, 354 or 355 days.
Furthermore, a leap year can also be deficient,
normal or full and have lengths of 383, 384 or 385
days. Thus, the six possible types are:
/-----REGULAR-----\
Month DEF NORM FULL
=============================
Tishri 30 30 30
Heshvan 29 29 30
Kislev 29 30 30
Tevet 29 29 29
Shevat 30 30 30
Adar (I) 29 29 29
Adar II -- -- --
Nisan 30 30 30
Iyyar 29 29 29
Sivan 30 30 30
Tammuz 29 29 29
Av 30 30 30
Elul 29 29 29
TOTALS 353 354 355
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/-----LEAP YEAR-----\
DEF NORM FULL
=============================
30 30 30
29 29 30
29 30 30
29 29 29
30 30 30
30 30 30
29 29 29
30 30 30
29 29 29
30 30 30
29 29 29
30 30 30
29 29 29
383 384 385
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Notice that the
period from Nisan 1 to Tishri 1 is always the
same: 177 days, regardless of the type of year.
By the application of certain rules discussed
below it is possible to accommodate all the
requirements of the Jewish calendar with a
sequence of years having only these six lengths.
Note that in a regular year Adar may be called
"Adar I" or simply "Adar" whereas in a leap year
the two Adars are called "Adar I" and "Adar II".
The process of establishing the calendar for a
particular year consists of the following steps:
a) determine if the year is a leap year, b) find
the day of the Molad (new moon) of Tishri for that
year, c) adjust its Rosh Hashanah date according
to the rules explained below, d) similarly,
determine the Rosh Hashanah date of the next year,
e) determine the length of the year (and hence its
type) to fill the duration between the two Rosh
Hashanah days. A set of rules has been established
for determining how to position the day of Rosh
Hashanah, given the day of the Molad.
Determining if a year is a leap year is done by
simply calculating its position in the 19-year
cycle which began in the year 1.
As was mentioned above, the duration between
lunar cycles is 29 days, 12 hours, 44 minutes and
3 1/3 seconds. If the time of one Molad is known,
the time of successive or previous ones can be
determined by adding or subtracting multiples of
this interval. From this process it is calculated
that the first new moon of the year 1 took place
on Sunday evening at 11 minutes, 20 seconds after
11 pm.
The time of the Tishri Molad for any year can be
determined by performing the previous calculation.
But, since the lunar cycle repeats every 19 years,
shortcuts can be taken. For example, it is only
necessary to add 2 days, 16 hours, 33 minutes and
3 1/3 seconds to a particular new moon to find the
day of the new moon exactly one 19-year-cycle
later. Or 2 days, 23 hours, 5 minutes and 33 1/3
seconds have to be added to a particular new moon
to find the new moon exactly 100 cycles (1900
years) later.
Now the following rules are applied: Tishri 1
(Rosh Hashanah) will be on the day of the Molad
except when falling into one of the four
exceptions below (which is more often than not),
in which case it is then delayed by one day.
Rule 1: When the new moon occurs on Wednesday,
Friday, or Sunday, or Rule 2: When the new moon
occurs at noon (18 hours after the start of the day
at sunset) or later, or Rule 3: When the new moon of
an ordinary year occurs on Tuesday at 11 minutes and
20 seconds after 3 am or later, or Rule 4: When, at
the termination of a leap year, the new moon occurs
on Monday at 32 minutes and 43 1/3 seconds after 9
am or later. When Rules 2, 3, or 4 apply, if
delaying Rosh Hashanah by one day causes it to fall
within Rule 1, it is delayed a second day. |
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EXPLANATION OF THE
FOUR RULES
The first rule causes the two holidays mentioned
above to fall only on the permissible days.
The second rule is an astronomical adjustment
which considers the relationship between the
observation of the new moon and the actual time of
the lunar conjunction. Since the moon is in
conjunction with the sun when it is "new", its
first crescent is most readily observed just after
sunset on the evening of the conjunction, but the
actual conjunction may have occurred many hours
before. The duration between the true conjunction
and the observation of this first crescent is a
complex calculation which takes into account the
season, the lunar latitude and the geographical
latitude and longitude of the place of
observation. The second rule is an adjustment for
the factors relating to the observation of the
first crescent moon from the city of Jerusalem.
The third rule accommodates the limitation
imposed by having only the six possible
year-lengths given above. If the new moon occurred
on the stated time (or later) the Rosh Hashanah
new moon of the following year would occur on
Saturday at noon (or later). This can be seen by
adding 4 days, 8 hours, 48 minutes and 40 seconds
(the time that must be added to a new moon to find
the new moon exactly 12 lunar months later) to 2
days, 3 hours, 11 minutes and 20 seconds. This
would call for the application of the first two
rules and the postponement of the Rosh Hashanah
from Saturday to Monday. This, in turn, would
require a year length of 356 days (50 weeks plus 6
days) which is not accommodated. So the Rosh
Hashanah is postponed to Thursday (Rule 1 applies)
and the year is 354 days long.
The fourth rule is also necessary to accommodate
the year length limitations but occurs very
infrequently. If one subtracts the time necessary
to calculate the new moon exactly 13 lunar months
earlier (5 days, 21 hours, 32 minutes and 43 1/3
seconds) one finds that the new moon at the start
of the year occurred at 12 noon on Tuesday. Under
Rules 1 and 2 it would have been postponed until
Thursday. This, in turn, would have required a
382-day leap year (54 weeks plus 4 days) which is
not accommodated. So Rosh Hashanah is postponed to
Tuesday and the year is 383 days long.
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SELECTING THE YEAR
TYPE
At this point, the Rosh Hashanah day calculation
is made for the next year. The starting day and
ending day of the year are then known as well as
whether it must be a leap year. The year type is
chosen from the six possibilities according to the
length required. A simple way to chose the type is
to use the table showing the number of days added
from one New Year's Day to the next.
Table 3
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Days Added to Year for Various Year Types
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Year Type Length Days Added
========================================
Deficient 353 3 days
Normal 354 4 days
Full 355 5 days
Deficient-Leap 383 5 days
Normal-Leap 384 6 days
Full-Leap 385 0 days
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The type is now easily determined by examining the
day of the week on which the year begins and ends.
The application of Rules 3 and 4 above have assured
us that these are the only types necessary to
accommodate all situations. The year is now
completely defined and the corresponding Gregorian
dates must be found. |
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CORRELATION TO THE
GREGORIAN CALENDAR
The correlation to the Gregorian calendar is very
unsophisticated. Simply stated: there is no direct
relationship between the Jewish and Gregorian
calendars. They both are related to the solar
cycle but according to totally different rules.
Every date, in the course of the 19-year cycle can
fall within a range of thirty days. The only way
to determine corresponding Gregorian dates is to:
1) Have a known correspondence as a reference
point. (Saturday, September 30, 1989, corresponds
to Tishri 1, 5750.)
2) Count how many days in one calendar system
exist between the reference date and the desired
date.
3) Count the same number of days from the
reference in the second calendar system. The
calculations can take advantage of certain
patterns to reduce their complexity. Charts and
tables have been drawn up to help or a computer
can be programmed to do the calculations.
It is interesting to note that the Christian
holiday of Easter and all the holidays tied to it
also retain a relation to the lunar cycle. In the
year 325, the date of Easter was set by the
Council of Nicaea to be the first Sunday after the
first full moon occurring on or after the vernal
equinox. Because the calculations of the full moon
and vernal equinox were too complex, the
calculation was simplified to assume that the
vernal equinox is always on March 21. Easter and
Passover usually come within a week of each other,
but in some Jewish leap years Passover occurs a
whole month after Easter.
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ANNIVERSARIES
Anniversaries can present a special problem for
the Jewish calendar because there are often days
that occur in one year which are absent in
another. In the Gregorian calendar there is only
one special case to con- sider, February 29th.
People born or married on that date can simply
decide to celebrate on February 28th or March 1st
for years that are not leap years. But the Jewish
calendar has an entire leap month as well as two
months which can vary in length, so special rules
have been establish- ed. The anniversary of the
death of a close relative (called a Yahrzeit) is
of particularly importance and has unique rules
associated with it.
1) The anniversary of a date which was the 30th of
Heshvan or Kislev in a year in which that month has
29 days is observed on the 1st of the next month.
There is an exception for the observance of a
Yahrzeit, namely: if, in the first year after the
death, the anniversary month has 29 days then the
Yahrzeit is observed on the 29th of that month and
continues to be observed on the 29th for all years
in which the anniversary month has only 29 days.
2) The anniversary of a date in Adar of an ordinary
year is observed on the same date in Adar II of a
leap year except for a Yahrzeit which is observed on
the same date in Adar I of a leap year.
3) The anniversary of a date in Adar I of a leap
year is observed on the same date in Adar of an
ordinary year. If the original date was the 30th of
Adar I of a leap year then, in an ordinary year, the
anniversary is observed on the 1st of Nisan. There
is an exception for the observance of a Yahrzeit. A
Yahrzeit is observed on the 29th of Adar in an
ordinary year.
4) The anniversary of a date in Adar II is observed
on the same date of Adar of an ordinary year. |
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THE GREGORIAN
CALENDAR
The calendar that we use today was first
formulated in several inaccurate variations by the
Romans. By the time of Julius Caesar January was
falling in autumn so he ordered Sosigenes to make
reforms to the calendar. He added 90 days to the
year 46 B.C. to correct for the seasonal drift and
adjusted the lengths of the months as we know them
to be today. He introduced the leap year by adding
one day to February every four years. The use of
the leap year was an improvement but not entirely
accurate. The true solar year is 365 days, 5
hours, 48 minutes, and 46 seconds. One 366-day
year every four years equates to an average year
of 365 days, 6 hours. Every four years an error of
44 minutes, 56 seconds was added.
By the 16th century the accumulated error was
ten days. Pope Gregory revised the calendar by
suppressing the ten days between October 5th and
October 15th of the year 1582 and ordained that
years ending in hundreds should not be leap years
unless they are divisible by 400. (1800 and 1900
were not leap years but 2000 is.) This Gregorian
calendar is the one we use today.
Incidentally, the Gregorian reform compensates
by 72 hours (3 days) every 400 years. The actual
excess accumulated is 74 hours, 53 minutes and 20
seconds. The error of 2 hours, 53 minutes and 20
seconds every 400 years accumulates to one day in
3323 years. Oh well, nobody's perfect.
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WEEKLY READINGS
The five books of the Old Testament (Torah) are
divided into 54 weekly portions which are read,
one each Sabbath, throughout the year. Only the
last portion, Ve-Zot-ha-Berakhah, is not read on
the Sabbath but on Simchat Torah. The new cycle
begins on the Sabbath after Simchat Torah. Each
weekly portion has an accompanying reading from
one of the Prophets (Haftarah). These are all
listed below.
Torah Reading Prophets
1. Bereshit, Gen 1:1-6:8 Isa 42:5-43:11
2. No'ah, Gen 6:9-11:32 Isa 54:1-55:5
3. Lekh Lekha, Gen 12:1-17:27 Isa 40:27-41:16
4. Va-Yera, Gen 18:1-22:24 II Kings 4:1-37
5. Hayyei Sarah, Gen 23:1-25:18 I Kings 1:1-31
6. Toledot, Gen 25:19-28:0 Mal 1:1-2:7
7. Va-Yeze, Gen 28:10-32:3 Hos 12:13-14:10
8. Va-Yishlah, Gen 32:4-36:43 Hos 11:7-12:12
9. Va-Yeshev, Gen 37:1-40:23 Amos 2:6-3:8
10. Mi-Kez, Gen 41:1-44:17 I Kings 3:15-4:1
11. Va-Yiggash, Gen 44:18-47:27 Ezek 37:15-28
12. Va-Yehi, Gen 47:28-50:26 I Kings 2:1-12
13. Shemot, Ex 1:1-6:1 Isa 27:6-28:13, 29:22-23
14. Va-Era, Ex 6:2-9:35 Ezek 28:25-29:21
15. Bo, Ex 10:1-13:16 Jer 46:13-28
16. Be-Shallah, Ex 13:17-17:16 Judge 4:4-5:31
17. Yitro, Ex 18:1-20:23 Isa 6:1-7:6,9:5
18. Mishpatim, Ex 21:1-24:18 Jer 34:8-22, 33:25-26
19. Terumah, Ex 25:1-27:19 I Kings 5:26-6:13
20. Tezavveh, Ex 27:20-30:10 Ezek 43:10-27
21. Ki Tissa, Ex 30:11-34:35 I Kings 18:1-39
22. Va-Yakhel, Ex 35:1-38:20 I Kings 7:40-50
23. Pekudei, Ex 38:21-40:38 I Kings 7:51-8:21
24. Va-Yikra, Lev 1:1-5:26 Isa 43:21-44:23
25. Zav, Lev 6:1-8:36 Jer 7:21-8:3, 9:22-23
26. Shemini, Lev 9:1-11:47 II Sam 6:1-7:17
27. Tazri''a, Lev 12:1-13:59 II Kings 4:42-5:19
28. Mezora, Lev 14:1-15:23 II Kings 7:3-20
29. Aharei Mot, Lev 16:1-18:30 Ezek 22:1-19
30. Kedoshim, Lev 19:1-20:27 Amos 9:7-15
31. Emor, Lev 21:1-24:23 Ezek 44:15-31
32. Be-Har, Lev 25:1-26:2 Jer 32:6-27
33. Be-Hukkotai, Lev 26:3-27:34 Jer 16:19-17:14
34. Be-Midbar, Num 1:1-4:20 Hos 2:1-22
35. Naso, Num 4:21-7:89 Judge 13:2-25
36. Be-Ha''alotkha, Num 8:1-12:16 Zech 2:14-4:7
37. Shela Lekha, Num 13:1-15:41 Josh 2:1-24
38. Korah, Num 16:1-18:32 I Sam 11:14-12:22
39. Hukkat, Num 19:1-22:1 Judge 11:1-33
40. Balak, Num 22:2-25:9 Micah 5:6-6:8
41. Pinhas, Num 25:10-30:1 I Kings 18:46-19:21
42. Mattot, Num 30:2-32:42 Jer 1:1-2:3
43. Masei, Num 33:1-36:13 Jer 2:4-28, 3:4
44. Devarim, Deut 1:1-3:22 Isa 1:1-27
45. Va-Ethannan, Deut 3:23-7:11 Isa 40:1-26
46. Ekev, Deut 7:12-11:25 Isa 49:14-51:3
47. Re''eh, Deut 11:26-16:17 Isa 54:11-55:5
48. Shofetim, Deut 16:18-21:9 Isa 51:12-52:12
49. Ki Teze, Deut 21:10-25:19 Isa 54:1-10
50. Ki Tavo, Deut 26:1-29:8 Isa 60:1-22
51. Nizzavim, Deut 29:9-30:20 Isa 61:10-63:9
52. Va-Yelekh, Deut 31:1-30 Isa 55:6-56:8
53. Ha''azinu, Deut 32:1-52 II Sam 22:1-51
54. Ve-Zot ha-Berakhah, Deut 33:1-34:12 Josh 1:1-18
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There are a sufficient number of portions to
accommodate different readings on the longer years
so it is necessary to double-up on some weeks in
shorter years in order that all the portions be
read. Also, there are special readings that are
substituted on the holidays. These substitutions
require a complex series of adjustments to be sure
that all portions are read regardless of the year
length. Special Haftarah readings are said when
celebrating a new moon. To further complicate the
matter, not all congregations observe the same
rules. JCAL shows the Torah and Haftarah reading
that normally would apply to that week as well as
the substitutions that are often made.
Note that for any particular date JCAL shows the
reading for the subsequent sabbath not for the
weekday or holiday reading that may occur on that
date.
The user is CAUTIONED to check these readings
inasmuch as there will be variations from
congregation to congregation.
Note, also, that if Tisha B'Av falls on the
Sabbath it is advanced by one day or if Yom
Haatzmaut falls on a Friday or Saturday it is
celebrated on the previous Thursday.
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SUNSET TIMES
When Item 4 is selected from the menu the time of
sunset is shown for the Gregorian date selected.
You can therefore calculate the time of sunset for
any holiday as well as for the sabbath. The time
of sunset is used to determine the time of
candlelighting. It is customary to light candles
on the Sabbath between 1 1/4 hours and 18 minutes
before sunset. Since sunset varies according to
one's location, it is necessary to tell the
computer where you are. The calculation is
controlled by parameters in a file called
JCAL.SUN. It consists of five lines. They must
contain the following:
Line 1: City Name Line 2: Latitude (Latitudes
south of the Equator are negative) Line 3:
Longitude (East of Greenwich are negative) Line 4:
Universal Time correction (zones east of Greenwich
are negative) Line 5: Name of time zone All lines
must be present. Latitude and longitude are in
degrees and minutes with a decimal point between
them. Thus 45 degrees, 37 minutes is written 45.37
Universal Time correction is according to the
following table:
Standard Daylight
Eastern 5 4
Central 6 5
Mountain 7 6
Pacific 8 7
Latitude and Longitude of common cities are
as shown:
Latitude Longitude
New York 40.45 73.59
Los Angeles 34.03 118.14
Chicago 41.52 87.38
Dallas 32.47 96.47
Miami 25.46 80.11
Montreal 45.30 73.33
San Francisco 37.46 122.24
Johannesburg -26.10 -28.02 (time correction = -1.5)
Jerusalem 31.47 -35.13 (time correction = -3)
Coordinates for other cities can be found in
an Almanac. |
If the file is found to be missing a default
file is automatically created which looks like
this:
New York
40.45
73.59
5
EST
New files can be created with any text file editor
or the default file can be edited. Its name must be
JCAL.SUN. |
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COMMAND LINE
PARAMETERS
There are two command line parameters that can be
used when starting the program. The letter "n"
will tell the program that there should be No
opening screen and the letter "m" will start the
program in a Monochrome mode. The latter uses two
intensities of white characters on a black
background and may give a better appearance on
monochrome or composite monitors. Command line
parameters can be entered in any order and can be
upper or lower case. They are separated by a
space. For example: to start JCAL (version 7.5) in
monochrome and without the opening screen enter
"JCAL75 m n". Note that you will need about 140k
of available memory to run JCAL with the text file
resident (selection 7) and about 80k without the
text file resident You will be informed if the
text file will not fit into memory.
JCAL UTILITIES
JCAL is supplied with several utilities that can
be used in conjunction with other software to
convert between Gregorian and Jewish dates.
J2G.EXE (Jewish-to-Gregorian) converts Jewish
dates to Gregorian, G2J.EXE (Gregorian-to-Jewish)
converts Gregorian dates to Jewish and
READINGS.EXE supplies the Torah readings for the
Sabbath following the Jewish date entered. They
accept their inputs as command line parameters and
send their outputs to the screen or to a file by
redirection.
Other application software such as dBASE III can
execute them as a DOS program using the RUN
command. Most programming languages have
equivalent commands. BASIC uses the SHELL command
and Turbo Pascal uses the EXEC command. dBase
programmers, however, may want to use the binary
files described later.
G2J.EXE This program is executed by entering the
following command:
G2J MM/DD/YYYY
MM/DD/YYYY is the Gregorian date to be converted
such as 7/30/1936. Month and Date can be single
digits but the year must be four digits. The
delimiter can be "/", "-", or "," . Thus 1-1-1989
or 3,17,1918 are also acceptable inputs.
The output is in the form MM/DD/YYYY. Month and
date may be single digits but the year is always
four digits. The months are given in numeric form
as follows:
Tishri 1 Heshvan 2 Kislev 3 Tevet 4 Shevat 5
Adar 6 Adar II 13 (when leap year); Nisan 7 Iyyar
8 Sivan 9 Tammuz 10 Av 11 Elul 12 Assigning the
number 13 instead of 7 to Adar II allows the
subsequent months to retain their same numbers
whether leap year or not. Thus Nisan is always
month 7 and Elul is always month 12 making
application programming and data entry easier.
Examples: G2J 7/28/1988 -- Sends 11/14/5748, the
Jewish equivalent of July 28, 1988, to the screen.
G2J 4,20,1970 > DFP.DAT -- Sends 7/14/5730,
the Jewish equivalent of April 20, 1970, to a file
called DFP.DAT.
There is a special command line parameter, "T"
or "t", for converting Today's date to the Jewish
equivalent. Today's date is read from the
computer's calendar and assumes it is correctly
set. This output is formatted in a more readable
form. Thus if today is July 30, 1988:
G2J T - Sends "Sat, Av 16, 5748" to the screen.
This command can be added to your AUTOEXEC.BAT
file so the current Jewish date will be shown on
the screen whenever you power up your computer.
G2J must be accessible to the AUTOEXEC.BAT file.
Using "TB" will give a "brief" output in the
form of MM/DD/YYYY which is less readable but is
convenient for piping into READINGS.EXE as
described below.
Example: G2J TB - Sends 11/16/5748 to the screen
if today is July 30, 1988.
J2G.EXE This program is executed by entering the
following command:
J2G MM/DD/YYYY S MM/DD/YYYY is the Jewish date
to be converted such as 11/15/5748. Month and Date
can be single digits but the year must be four
digits. The date delimiter can be "/", "-", or ","
.
S is the number of successive years. It can be
any size but the larger the number the longer the
computation time. S is optional and defaults to 1
if not used. The outputting of successive years is
particularly useful when calculating anniversaries
and Yahrzeits for several years ahead.
The output is in the form MM/DD/YYYY. Here, too,
month and date may be single digits but the year
is always four digits. The months are given in
numeric form as described above. Remember that
"13" is used to designate the leap year month of
Adar II.
Examples: J2G 11/16/5748 -- Sends 7/30/1988 to
the screen.
J2G 7/14/5730 20 > OUTFILE.DAT -- Sends 20
successive Gregorian dates starting with 4/20/1970
to a file named OUTFILE.DAT.
READINGS This program takes the Jewish date
entered at the command line and outputs the Torah
reading for the Sabbath following that date. If no
command line parameter is entered, the program
waits for a date to be entered on the next line.
NOTE THAT NO PROMPT IS SUPPLIED. This is done so
that the output is only the Torah reading which
can be redirected to another file without clutter.
Examples: READINGS 11/11/5709 > BAR -- Sends
"Va-Ethannan, Deut 3:23 -7:11" to a file called
BAR.
The ability of this program to accept input on a
separate line without command line parameters
makes it particularly easy to have its input
supplied by piping it from G2J as illustrated
below.
G2J 8/6/1949 | READINGS will output the same
"Va-Ethannan, Deut 3:23 - 7:11" to the screen.
If you place the following lines in your
AUTOEXEC.BAT file you will see the date and the
Torah reading displayed each time you boot up your
computer:
G2J T G2J TB | READINGS
dBASE Interface Two binary files J2GBIN.BIN and
G2JBIN.BIN are also included. These can be LOADed
and CALLed by a dBase program and are much faster
than using the RUN command. They both require that
a single date string be passed to it in the form
MM/DD/YYYY. The converted date is returned in the
same string variable. The variable MUST be padded
to have a length of ten characters. A small
demonstration is included to show the programmer
how to use them. There are two additional files
associated with the demo: JDB.PRG, JDB.DBF. Run
JDB.PRG under dBASE III and study the code
carefully to integrate the utilities into your
application.
SHAREWARE
Rather than marketing these programs I am
distributing them as Shareware. Try the programs
at no charge. They are not copy protected and you
may distribute them freely to others. If you find
them useful and continue to use them you must pay
the $18 registration fee. Send the registration
fee along with the program revision number (from
the opening screen) to:
Lester Penner 25 Shadow Lane Great Neck, NY 11021
(H) 516 466-5574 (W) 516 273-3100 Please send only
US currency; no Canadian checks.
You may send information about bugs to the same
address or to Compuserve 75236,1572.
Enjoy, Les
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ABOUT THIS PROGRAM
Download
this
program
JCAL75.EXE
is a program that calculates dates of the
Jewish calendar. It was compiled with
Turbo Pascal 5.5 and is based on three
descriptions of the Jewish calendar which
I recommend as additional reading on the
subject:
- The Jewish Calendar Mystery Dispelled
by George Zinberg, Vantage Press, 1963
- The Encyclopedia Judaica, "Calendar"
- The
Comprehensive Hebrew Calendar by
Arthur Spier, Behrman House, Inc.
THE JEWISH CALENDAR
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Note: The above mentioned
program does not seem to be available any longer.
O.K. the program was found again on August
12, 2004 & the link updated however it
doesnot always work. You can download
from here.
The Laodicean Times. webmaster@laodiceantimes.com
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