Last modified: 12 December 2018

How do I create a contour plot of an image?

Contour plots of FITS images can be created using either make_figure or add_contour:

make_figure("img.fits", [1,2,3])
make_figure("img.fits", [1,2,3], ["color","red"])

add_contour("img.fits", [1,2,3])
add_contour("img.fits", [1,2,3], ["color","red"])

These commands create a contour plot of the image img.fits using: a set of default contour levels calculated from the image, the contour levels 1,2,3, and the contour levels 1,2,3 along with using a red color to draw the contours.

The add_ds9_contour routine can be used to draw contour files created by ds9.

The ChIPS Gallery

More examples can be seen in the ChIPS Gallery.

Unsupported WCS projections

The add_contour, add_image, and make_figure commands will warn you if given an image with an unsupported WCS projection (that is, everything but a tangent-plane projection), and fall back to using the physical or logical systems. An example of the warning is:

chips WARNING: Unable to use world transform - RA---SIN, DEC--SIN is an unsupported type. Using physical transform.