# Detecting NULL values in FITS tables

**URL:** <https://community.openastronomy.org/t/detecting-null-values-in-fits-tables/731>\
**Category:** Astropy\
**Tags:** table\
**Created:** [September 1, 2023, 9:38pm UTC](https://community.openastronomy.org/t/detecting-null-values-in-fits-tables/731 "2023-09-01T21:38:54Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![SteveAllen-UCOLick](https://dub1.discourse-cdn.com/flex005/user_avatar/community.openastronomy.org/steveallen-ucolick/32/411_2.png) [@SteveAllen-UCOLick](https://community.openastronomy.org/u/SteveAllen-UCOLick)\
**Post date:** [September 1, 2023, 9:38pm UTC](https://community.openastronomy.org/t/detecting-null-values-in-fits-tables/731/1 "2023-09-01T21:38:54Z")

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I am reading a FITS ASCII table which has several floating point columns with values that match their TNULLn card. After fits.open on the file I see the NULL columns with value 0.  
How can I test whether the value in the original FITS table was NULL?