File:Delta t.svg
Summary
| Description |
English: Plot of ∆T = TT − UT as a function of time, where TT is Terrestrial Time and UT is Universal Time. This plot combines the data sets Historic Delta T and LOD (1657.0 – 1973.0) and Monthly determinations of Delta T (from 1973-02-01 onwards) from the IERS Rapid Service/Prediction Center. |
| Date | |
| Source | Own work |
| Author | Musashiaharon |
| Other versions |
Delta T.jpg:  (1657 – 1984), TT-UT function of time.png:  (1657 – 1994), Delta T 1657-2022.svg:  (1657–2022) |
This W3C-unspecified plot was created with Gnuplot.Category:Unspec SVG created with Gnuplot#00050727Delta%20t.svg
Source
#!/bin/sh
tail -n +3 historic_deltat.data |
awk '{ print $1 "\t" $2; } /1973/ { exit; }' > hist.data
awk '
{
# use gdate on osx after brew install coreutils. On linux, use date.
doy = "gdate +%j --date=" $1 "-" $2 "-" $3; doy |getline dayOfYear; close(doy)
diy = "gdate +%j --date=" $1 "-12-31"; diy |getline daysInYear; close(diy)
printf("%0.3f\t%s\n", $1 + ((dayOfYear - 1)/daysInYear), $4);
}' < deltat.data >> hist.data
#!/usr/bin/env gnuplot
set terminal svg size 640, 480 name "Delta_t"
set output 'Delta_t.svg'
set title "∆T = TT − UT"
set xlabel "year"
set ylabel "∆T (s)"
set grid linetype 1 linecolor rgb "#cccccc"
unset key
set style data lines
set style line 1 linetype 1 linewidth 2
set style increment user
set xzeroaxis linetype 2 linecolor rgb "black"
plot 'hist.data' linetype rgb "#FF0000"
Licensing
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