I'm looking for a way to draw an horizontal line (or to "shadow") the following graphic in gnuplot to show day vs night:
The script to generate this image is:
set autoscale
set title "Campo magnetico terrestre - Intensidad - Ultimas 24hs"
set title font "Freesans, 11"
set timefmt '%Y-%m-%d %H:%M:%S'
set xdata time
set xtics font "Freesans, 9"
set ytics font "Freesans, 9"
set xlabel font "Freesans, 9"
set ylabel font "Freesans, 9"
set key font "Freesans,9"
set key left center
set xlabel "Fecha/Hora"
set ylabel "Campo (mG)"
set terminal png enhanced size 1200,600
set output "dia.png"
set grid y
set grid x
set datafile separator '|'
plot "< sqlite3 /data/magneto/magneto.db 'select * from v_dia'" using 1:2 title 'X' with lines, \
"< sqlite3 /data/magneto/magneto.db 'select * from v_dia'" using 1:3 title 'Y' with lines, \
"< sqlite3 /data/magneto/magneto.db 'select * from v_dia'" using 1:4 title 'Z' with lines, \
"< sqlite3 /data/magneto/magneto.db 'select * from v_dia'" using 1:5 title 'Total' with lines
Could you please give me some help? Thanks in advance!