<p>I'm not quite sure how I find the orbital phase  (<span class="math-container">$\phi$</span>) of a transitting exoplanet. For example, I have this RV data <a href="http://iopscience.iop.org/article/10.1088/2041-8205/713/2/L140/pdf" rel="nofollow noreferrer">in this article</a>:</p>

<p><a href="https://i.sstatic.net/W5uw6.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/W5uw6.png" alt="enter image description here"></a></p>

<p>First of all, I don't know how that phase or "cycles" is derived. But that's not the phase <span class="math-container">$\phi$</span> I'm looking for but this (in the same article):</p>

<p><a href="https://i.sstatic.net/ccHuM.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ccHuM.png" alt="enter image description here"></a> </p>

<p>As you see, that phase goes from 0 to 1, and I know it has to do with the time of passage from the periastron and the data time (the HJD column), but I'm not able to derive this number in the interval [0,1]. So, if we assume the orbital parameters are known, how can we derive that number?</p>

<exoplanet><orbital-elements><radial-velocity>
Calculate the orbital phase when plotting the Radial Velocity data of a transitting exoplanet
Carlos Vázquez Monzón
# Calculate the orbital phase when plotting the Radial Velocity data of a transitting exoplanet

(Asked by: username_0 on 2018-12-26)

I'm not quite sure how I find the orbital phase ($\phi$) of a transitting exoplanet. For example, I have this RV data [in this article](http://iopscience.iop.org/article/10.1088/2041-8205/713/2/L140/pdf):

[![enter image description here](https://i.sstatic.net/W5uw6.png)](https://i.sstatic.net/W5uw6.png)

First of all, I don't know how that phase or "cycles" is derived. But that's not the phase $\phi$ I'm looking for but this (in the same article):

[![enter image description here](https://i.sstatic.net/ccHuM.png)](https://i.sstatic.net/ccHuM.png)

As you see, that phase goes from 0 to 1, and I know it has to do with the time of passage from the periastron and the data time (the HJD column), but I'm not able to derive this number in the interval [0,1]. So, if we assume the orbital parameters are known, how can we derive that number?

**Tags:** exoplanet, orbital-elements, radial-velocity

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## 0 answers

