But `text' can do even more. With
text "$#3$" at 0 20 along declination
tics rectascension 1 towards N ;
text "$#5$" at 11 0 along declination
tics declination 10 towards S ;
you create automatic tic mark labels at the +20^\circ declination
circle and the 11h rectascension circle. See Tic mark labels,
for more information about these placeholders like #3.
Typically you will embed the placeholders in $...$, because this
tells the underlying TeX typesetting engine to typeset the number as
a formula. This makes it look nicer.