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diff --git a/noao/astutil/doc/precess.hlp b/noao/astutil/doc/precess.hlp new file mode 100644 index 00000000..64475c56 --- /dev/null +++ b/noao/astutil/doc/precess.hlp @@ -0,0 +1,63 @@ +.help precess Oct87 noao.astutil +.ih +NAME +precess -- general astronomical coordinate precession +.ih +USAGE +precess files startyear endyear +.ih +PARAMETERS +.ls files +The name of a file (or a file list or template) containing the coordinates +to be precessed. +.le +.ls startyear +The default equinox of the input coordinates. +.le +.ls endyear +The default target year to which the coordinates will be precessed. +.le +.ls stdepoch = 0 +If nonzero, coordinates will be output precessed to both \fBendyear\fR +and the specified standard epoch. +.le +.ih +DESCRIPTION +Coordinates are read from the input file as RA and DEC pairs, +one pair per input line. Each coordinate pair may optionally be followed +by the equinox of the input coordinates (if different from the default) +and the epoch of the output coordinates. +Coordinates may be entered in either decimal or sexagesimal notation. +The given coordinates are rotated according to the +precession rates to the requested year and printed on the standard output. +Basic data is taken from the Explanation to the American Ephemeris. +.ih +EXAMPLES +Precess coordinate entered interactively from 1950 to 1990, except where +the dates are specified otherwise on the command line (lines input by the +user are marked: + +.nf + cl> precess STDIN 1950 1990 [input] + 12:30:10.12 10:18:27.5 [input] + 12:32:11.79 10:05:13.09 1990.0 + 12:30 10:18 [input] + 12:32:01.68 10:04:45.51 1990.0 + 12:30 -20 1900 [input] + 12:34:42.89 -20:29:46.29 1990.0 + 12:30 -20 1900 2000 [input] + 12:35:14.40 -20:33:04.40 2000.0 + (eof=<ctrl/z>) [input] +.fi + +The following is equivalent, except that coordinate input is taken from +the file "coords", rather than from the terminal: + +.nf + cl> precess coords 1950 1990 [input] + 12:32:11.79 10:05:13.09 1990.0 + 12:32:01.68 10:04:45.51 1990.0 + 12:34:42.89 -20:29:46.29 1990.0 + 12:35:14.40 -20:33:04.40 2000.0 +.fi +.endhelp |