Contents of the JCAL.TXT file
JCAL - THE JEWISH CALENDAR PROGRAM
ABOUT THIS PROGRAM
JCAL74.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:
1. The Jewish Calendar Mystery Dispelled by George Zinberg, Vantage
2. The Encyclopedia Judaica, "Calendar"
3. The Comprehensive Hebrew Calendar by Arthur Spier, Behrman House,
THE JEWISH CALENDAR
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
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.
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
Year Event Comment
====== ======== ================
1 Adam The Creation
1057 Noah 1056 years from Adam to Noah
1949 Abraham 892 years from Noah to Abraham
2049 Isaac 100 years from Abraham to Isaac
2239 Entrance into Egypt 190 years from Isaac to Egypt
2449 The Exodus 210 years from Egypt to Exodus
2929 Dedication of First Temple 480 years from Exodus to 1st Temple
3339 Destruction of First Temple 410 years duration of 1st Temple
3409 Return to Israel 70 years of Babylonian Exile
3829 Destruction of Second Temple 420 years duration of 2nd Temple
Ancient names for the months are mentioned in Deuteronomy and I
Kings 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.
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 - Basis of Jewish Calendar
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
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 - Jewish Holidays
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 25 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
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-----\ /-----LEAP YEAR-----\
Month DEF NORM FULL DEF NORM FULL
Tishri 30 30 30 30 30 30
Heshvan 29 29 30 29 29 30
Kislev 29 30 30 29 30 30
Tevet 29 29 29 29 29 29
Shevat 30 30 30 30 30 30
Adar (I) 29 29 29 30 30 30
Adar II -- -- -- 29 29 29
Nisan 30 30 30 30 30 30
Iyyar 29 29 29 29 29 29
Sivan 30 30 30 30 30 30
Tammuz 29 29 29 29 29 29
Av 30 30 30 30 30 30
Elul 29 29 29 29 29 29
TOTALS 353 354 355 383 384 385
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
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.
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.
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 - Days Added to Year for Various Year Types
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
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.
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
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.
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
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
4) The anniversary of a date in Adar II is observed on the same date of
Adar of an ordinary year.
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
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
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.
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 advanced
to the previous Thursday.
The user is CAUTIONED to check these readings inasmuch as there will be
variations from congregation to congregation.
When Item 4 is selected from the menu the time of sunset is shown.
This can be 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
Line 3: Longitude
Line 4: Universal Time correction
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:
Eastern 5 4
Central 6 5
Mountain 7 6
Pacific 8 7
Latitude and Longitude of common cities are as shown:
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
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 files can be created with any text file editor or the default file
can be edited. Its name must be JCAL.SUN.
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 7.4) in monochrome and without the opening screen
enter "JCAL74 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 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
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.
This program is executed by entering the following command:
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:
Adar II 13 (when leap year);
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.
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,
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
Example: G2J TB - Sends 11/16/5748 to the screen if today is July
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.
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.
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.
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 also place the following line in your AUTOEXEC.BAT file you
will see the Torah reading displayed each time you boot up your
computer: G2J TB | READINGS
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.
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:
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