<p>This is not an answer, but it is too long to put in the comment.</p>

<p>I am not familiar with quasars. In general, converting fluxes from an observed frame to a rest frame requires following consideration: extinction correction, cosmological expansion, k-correction. I think the simplest form is <span class="math-container">$f_{rest} = (1 + z)^n f_{obs}$</span> where <span class="math-container">$z$</span> is redshift and <span class="math-container">$n$</span> is some integer depending on how to express the unit of fluxes. This considers only the cosmological expansion. But, I am not sure if this transformation is valid with your quasars because they might be too far that <span class="math-container">$(1+z)^n$</span> is no longer a good approximation.</p>

CC BY-SA 4.0
2018-10-25T12:45:50.840Z
Dear Kornpob, I thank you very much. My quasars are not too far, they are between z=.158 and 0.859. It was my guess that the expression  f_rest=(1+z) F_obs  works for my case. I want to consider only the cosmological expansion.  I appreciate your help.
Bizuzina
CC BY-SA 4.0
2018-10-25T04:39:34.390Z
2018-10-25T04:39:34.390Z
Kornpob Bhirombhakdi
<p>I have flux time series of quasars in the observed frame and want to convert it in the rest or quasar frame. Any one who can help? Thanks</p>

CC BY-SA 4.0
2019-04-23T07:57:31.380Z
As you mention that you have time series, I guess that you worry about cosmic time dilation (i.e., what happens to the time axis) more than about what happens to the flux. If true, you could clarify this in the question.
mtewes
CC BY-SA 4.0
2018-10-25T04:31:43.647Z
I am not familiar with quasars. In general, converting fluxes from an observed frame to a rest frame requires following consideration: extinction correction, cosmological expansion, k-correction.
Kornpob Bhirombhakdi
<observational-astronomy>
How to convert quasar flux time series from observed frame to rest frame?
Bizuzina
# How to convert quasar flux time series from observed frame to rest frame?

(Asked by: username_0 on 2018-10-24)

I have flux time series of quasars in the observed frame and want to convert it in the rest or quasar frame. Any one who can help? Thanks

**Tags:** observational-astronomy
> **Comments:**
> **username_2**: I am not familiar with quasars. In general, converting fluxes from an observed frame to a rest frame requires following consideration: extinction correction, cosmological expansion, k-correction.  
> **username_1**: As you mention that you have time series, I guess that you worry about cosmic time dilation (i.e., what happens to the time axis) more than about what happens to the flux. If true, you could clarify this in the question.  

---

## 1 answers

### Answer by username_2 on 2018-10-25. Score: 1

This is not an answer, but it is too long to put in the comment.

I am not familiar with quasars. In general, converting fluxes from an observed frame to a rest frame requires following consideration: extinction correction, cosmological expansion, k-correction. I think the simplest form is $f\_{rest} = (1 + z)^n f\_{obs}$ where $z$ is redshift and $n$ is some integer depending on how to express the unit of fluxes. This considers only the cosmological expansion. But, I am not sure if this transformation is valid with your quasars because they might be too far that $(1+z)^n$ is no longer a good approximation.

> **Comments:**
> **username_0**: Dear Kornpob, I thank you very much. My quasars are not too far, they are between z=.158 and 0.859. It was my guess that the expression  f_rest=(1+z) F_obs  works for my case. I want to consider only the cosmological expansion.  I appreciate your help.  

---

