# Question about SkyCoord. radial\_velocity\_correction

**URL:** <https://community.openastronomy.org/t/question-about-skycoord-radial-velocity-correction/1199>\
**Category:** Astropy\
**Tags:** question\
**Created:** [February 5, 2025, 1:31am UTC](https://community.openastronomy.org/t/question-about-skycoord-radial-velocity-correction/1199 "2025-02-05T01:31:51Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![caseylam](https://dub1.discourse-cdn.com/flex005/user_avatar/community.openastronomy.org/caseylam/32/612_2.png) [@caseylam](https://community.openastronomy.org/u/caseylam)\
**Post date:** [February 5, 2025, 1:31am UTC](https://community.openastronomy.org/t/question-about-skycoord-radial-velocity-correction/1199/1 "2025-02-05T01:31:51Z")

</div>

I have a question about the format of the time passed into obstime in the radial\_velocity\_correction function ([SkyCoord — Astropy v7.0.0](https://docs.astropy.org/en/stable/api/astropy.coordinates.SkyCoord.html#astropy.coordinates.SkyCoord.radial_velocity_correction))

Looking at the Wright and Eastman paper which is the reference, it seems like times should be in BJD. But that is not an available format for radial\_velocity\_correction (JD is allowed, but not HJD or BJD).

Should the time passed into radial\_velocity\_correction be JD (which means the function performs the conversion to BJD internally), or should the user be converting JD into BJD, and then passing that into obstime?