title: CFITSIO custom axis
body: <p>I am doing a final project with fits files and for that reason, I am using cftisio library.
  However, I have found some doubts about how to create images. One of them is about their axis.</p>
  <p>As a example, Can I create an image where the x axis goes from 45 to 840 in steps of 5?</p>