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tepoch -- Convert time between different formats in a table.


tepoch input incol outcol qualifier outfmt outtype


This task offers a convenient tool to convert time data between several formats in a table. It is based on the task EPOCH. See the help file of EPOCH for more details.

This task covers two categories of time formats:

1) A qualifier followed by one or more arguments, e.g., JD2440000 where JD is the qualifier and 2440000 is the argument. In this task the qualifier can either be part of the value or be specified in the user parameter.
(2) Civil calendar, e.g., Nov 11, 1953, or 11/20/79.

This task has most features of EPOCH:

(1) Case insensitivity, e.g., the following are equivalent: (a) JD or jd, (b) NOVEMBER, november, or November.
(2) In most cases, input strings can be "sloppy", e.g., there can be one or more spaces or tabs or no space at all between the qualifier and its argument.
(3) Liberal use of delimiters is allowed, e.g., March 28, 1953 can be specified as "Mar 28, 1953", or "Mar. 28, 1953", or "Mar-28-1953".

Civil calendar dates can be specified using virtually any punctuation---including dashes---to separate day, month, and year. Because the dash is the same character as the minus sign, the minus sign loses its arithmetic meaning, and negative day, month or year can not be used in input strings.

The suffix BC (or B.C.) can be used in its usual meaning, e.g., 1 BC = 0 AD, 2 BC = -1 AD, etc. Minus signs retains their arithmetic significance for input strings of the first category (qualifier and argument). The suffix AM or PM is also supported.

There is a limit on how far into the past or future this task can go. The limit is about +/- 2.1 billion days or +/- 5.8 million years from now. If the input argument exceeds this limit, an error message will be issued.


input [string]
Input table name.
incol [string]
Input time column name.
outcol [string]
Output time column name.
qualifier [string = ""]
The qualifier used to specify time strings of the first category (see description above). When this parameter is set, input values need only to include the argument, for example:

"JD 2460000" 

is equivalent to 

"2460000" qualifier="jd"

You can have redundant qualifier:

"JD2460000" qualifier="jd"

but NOT inconsistent qualifiers:

"jd2460000" qualifier="dmf"

The following values are allowed as the qualifier:
(1) JD, Julian date.
(2) MJD, modified Julian date, i.e., MJD = JD - 2400000.5.
(3) J, Julian epoch, i.e., 2000.0 + (JD-2451545) / 365.25.
(4) B, Besselian epoch, i.e., 1900.0 + (JD-2415020.31352) / 365.242198781.
(5) DMF, number of seconds since January 1, 1980, 0h.
(6) SMS, yyyy.ddd hh:mm:ss.
(7) CDBS, the calibration data base time format, The number of digits must be preserved, i.e., if the month is a single digit, a zero must be filled in for the first month digit. Information after the colon (including the colon) is optional.
(8) GEISUT, this qualifier needs two arguments that represent the integer representations of UTC found in the standard header packet file header. The first argument is UTCO1 (bytes 5-8 of UTCO) second is UTCO2 (byte 1-4 of UTCO). The two arguments must be separated by at least one space or tab.
(9) EPCHTIME, number of seconds since January 1, 1985, 0h.
(10) TIMEFFEC, same as EPCHTIME.
(11) OBSSTRTT, number of seconds since January 0, 1985, 0h.
(12) ENG, the engineering format, YMDhhmm, Y is the year. It has the range of 1-9 and A-Z where 1 = 1981 and A = 1990, B = 1991, Z = 2015, etc. M is the month. It has the range of 1-9 and A-C where 1 = January and A = October. D is the day. It has the range of 1-9 and A-V where 1 = 1st and A = 10th. Hours are two digits (00-24), so are minutes (00-60). In the output, if the year is out of range, it prints a "*".
outfmt [string = ""] [string, Allowed values: date|jd|mjd|sms|dmf|eng]
The output time format.
outtype [string = "s"] [string, Allowed values: s|d|p]
The output data type. The value "d" is for double precision, it does not apply to the output formats of "date" or "eng". The value "s" is string and applies to any format. The value "p" will attach the qualifier as a prefix to the output value. For example, if outtype = "s" and outfmt = "mjd", the output is simply, e.g., "54321". But if outtype = "p", then the output is "MJD 54321".
(dmy_style = "mdy") [string, Allowed values: mdy|dmy|ymd]
The order of day, month, year if the input time string is of the second category. The default is the American style (month, day, year).
(add= yes) [boolean]
Add 1900 to the year if it is less than 100?
(calendar = "ns") [string, Allowed values: ns | os]
Specifies whether the input time string is Gregorian calendar ("ns", new style) or Julian calendar ("os", old style).

Please read the help file of EPOCH for more details.


1. Convert the year-month-day string in the first column of table jctb to Julian days and put them in the third column as strings:

    tepoch jctb c1 c3 "" "jd" "s"





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