implemented scan of astronomical julian day (JDN/ID) with token `%Ej`, corresponds julian date of sqlite-database.

In opposite to calendar julian day `%J`, it starts the day at noon (and can parse float, so contains a time fraction).
**TODO** implement `clock format ... -format %Ej` and test-cases for format of this token.
**TODO** implement `%EJ` token for calendar JD with time fraction.

1 files changed, 17 insertions, 1 deletions

diff --git a/doc/clock.n b/doc/clock.n
index 0dae993..4294412 100644
--- a/doc/clock.n
+++ b/doc/clock.n
@@ -400,6 +400,9 @@ seconds from the epoch, that group is used to determine the date.
 .IP [2]
 If the string contains a \fB%J\fR format group, representing
 the Julian Day Number, that group is used to determine the date.
+Note, that in case of \fB%Ej\fR format group, representing
+the astronomical Julian Date (with time fraction), this group is used
+to determine the date and time.
 .IP [3]
 If the string contains a complete set of format groups specifying
 century, year, month, and day of month; century, year, and day of year;
@@ -550,6 +553,19 @@ abbreviation appropriate to the current locale, and uses it to fix
 whether \fB%Y\fR refers to years before or after Year 1 of the
 Common Era.
 .TP
+\fB%Ej\fR
+On output, produces a string of digits giving the Astronomical Julian Date or
+Astronomical Julian Day Number (JDN/JD). In opposite to calendar julian day
+\fB%J\fR, it starts the day at noon.
+On input, accepts a string of digits (or floating point with the time fraction)
+and interprets it as an Astronomical Julian Day Number (JDN/JD).
+The Astronomical Julian Date is a count of the number of calendar days
+that have elapsed since 1 January, 4713 BCE of the proleptic
+Julian calendar, which contains also the time fraktion (after floating point).
+The epoch time of 1 January 1970 corresponds to Astronomical JDN 2440587.5.
+This value corresponds the julian day used in sqlite-database, and is the same
+as result of \fBselect julianday(:seconds, 'unixepoch')\fR.
+.TP
 \fB%Es\fR
 This affects similar to \fB%s\fR, but in opposition to \fB%s\fR it parses
 or formats local seconds (not the posix seconds).
@@ -605,7 +621,7 @@ On output, produces a three-digit number giving the day of the year
 (001-366).  On input, accepts such a number.
 .TP
 \fB%J\fR
-On output, produces a string of digits giving the Julian Day Number.
+On output, produces a string of digits giving the calendar Julian Day Number.
 On input, accepts a string of digits and interprets it as a Julian Day Number.
 The Julian Day Number is a count of the number of calendar days
 that have elapsed since 1 January, 4713 BCE of the proleptic