# Overlaying a FK5 FITS image as contours on top of a ICRS FITS colorscale image (with aplpy)

**URL:** <https://community.openastronomy.org/t/overlaying-a-fk5-fits-image-as-contours-on-top-of-a-icrs-fits-colorscale-image-with-aplpy/473>\
**Category:** Astropy\
**Tags:** astropy, fits\
**Created:** [October 10, 2022, 12:58pm UTC](https://community.openastronomy.org/t/overlaying-a-fk5-fits-image-as-contours-on-top-of-a-icrs-fits-colorscale-image-with-aplpy/473 "2022-10-10T12:58:02Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![chentao.yang](https://dub1.discourse-cdn.com/flex005/user_avatar/community.openastronomy.org/chentao.yang/32/286_2.png) [@chentao.yang](https://community.openastronomy.org/u/chentao.yang)\
**Post date:** [October 10, 2022, 12:58pm UTC](https://community.openastronomy.org/t/overlaying-a-fk5-fits-image-as-contours-on-top-of-a-icrs-fits-colorscale-image-with-aplpy/473/1 "2022-10-10T12:58:02Z")

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I am trying to use Aplpy to plot a colorscale image and overlay another FITS image as contours. However, the colorscale-imaged FITS uses ICRS while the contours FITS uses FK5. I found when I am plotting them, the difference in the coordinate system is not corrected.

Is there a way to put both under, e.g. ICRS, to match the coordinate system properly?

Thanks a lot!