<p>I have a data cube which has 3 axes: <code>x(GLAT), y(GLON), v(VELO)</code>. Every pixel has value <span class="math-container">$T(x,y,v)$</span> in the unit of <code>K</code>. The velocity is in <code>m/s</code>, reference to <code>1420405751.77 MHz</code>.</p>
<p>if I measure a cloud with flux density:</p>
<div class="s-table-container"><table class="s-table">
<thead>
<tr>
<th style="text-align: center;">T (K)</th>
<th style="text-align: center;">1</th>
<th style="text-align: center;">1</th>
<th style="text-align: center;">4</th>
<th style="text-align: center;">5</th>
<th style="text-align: center;">1</th>
<th style="text-align: center;">4</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align: center;">v (m/s)</td>
<td style="text-align: center;">0</td>
<td style="text-align: center;">200</td>
<td style="text-align: center;">400</td>
<td style="text-align: center;">600</td>
<td style="text-align: center;">800</td>
<td style="text-align: center;">1000</td>
</tr>
</tbody>
</table></div>
<p>how can I calculate the flux of this cloud in Jy?</p>
<p>This data is produced by the Chinese FAST telescope. Example data cube here: <a href="https://hiverse.alkaidos.cn/" rel="nofollow noreferrer">https://hiverse.alkaidos.cn/</a></p>
<p><a href="https://i.sstatic.net/cWFap1Kg.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/cWFap1Kg.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2024-12-02T17:38:53.970Z
I don't quite get what velocity you have there. Is it a line-of-sight velocity, thus a redshift(?) with respect to the indicated frequency?
planetmaker
CC BY-SA 4.0
2024-12-02T23:32:31.043Z
What does temperature multiply by velocity means? Its kinda problematic.
Polaris5744
CC BY-SA 4.0
2024-12-03T06:38:51.603Z
1. the velocity is a redshift respect to LSR, for example, v=0 is f=1420MHz, then v=1km/s is z = v/c = δf/f , f = (1-v/c)f
2. @Polaris5744 , this temperature is brightness temperature I=2ν^2 kT/c, I know you don't know this so stop commenting here.
Firestar-Reimu
CC BY-SA 4.0
2024-12-03T06:46:15.513Z
@Firestar-Reimu, what are you talking about, I don't even know who you are, you must have confuse me with someone else.
Polaris5744
<radio-astronomy><radiation><units>
How to convert the unit of flux from K*m/s to Jy?
Firestar-Reimu
# How to convert the unit of flux from K*m/s to Jy?

(Asked by: username_0 on 2024-10-22)

I have a data cube which has 3 axes: `x(GLAT), y(GLON), v(VELO)`. Every pixel has value $T(x,y,v)$ in the unit of `K`. The velocity is in `m/s`, reference to `1420405751.77 MHz`.

if I measure a cloud with flux density:

| T (K) | 1 | 1 | 4 | 5 | 1 | 4 |
| --- | --- | --- | --- | --- | --- | --- |
| v (m/s) | 0 | 200 | 400 | 600 | 800 | 1000 |

how can I calculate the flux of this cloud in Jy?

This data is produced by the Chinese FAST telescope. Example data cube here: <https://hiverse.alkaidos.cn/>

[![enter image description here](https://i.sstatic.net/cWFap1Kg.png)](https://i.sstatic.net/cWFap1Kg.png)

**Tags:** radio-astronomy, radiation, units
> **Comments:**
> **username_1**: I don't quite get what velocity you have there. Is it a line-of-sight velocity, thus a redshift(?) with respect to the indicated frequency?  
> **username_2**: What does temperature multiply by velocity means? Its kinda problematic.  
> **username_0**: 1. the velocity is a redshift respect to LSR, for example, v=0 is f=1420MHz, then v=1km/s is z = v/c = δf/f , f = (1-v/c)f 2. @Polaris5744 , this temperature is brightness temperature I=2ν^2 kT/c, I know you don't know this so stop commenting here.  
> **username_2**: @Firestar-Reimu, what are you talking about, I don't even know who you are, you must have confuse me with someone else.  

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## 0 answers

