<p>I have an image of an <strong>extended source</strong> obtained with an interferometer (after imaging the uv-data). The image consist of a certain number of pixels, with unit of <strong>Jy/beam</strong>. Somewhere on the image is a source, whose size is greater than my (synthesized) beam size.</p>
<ol>
<li><p>How do I compute the total flux of the source (<strong>in Jy</strong>!), knowing the flux of each pixels and the area of the beam (in pixels)?</p>
</li>
<li><p>How do I compute the corresponding signal to noise ratio (SNR), knowing the standard deviation of the flux of individual pixels (far from the source)?</p>
</li>
</ol>
<p><strong>Note:</strong> While answers to <a href="https://astronomy.stackexchange.com/q/26721/7982">Converting Jy/beam to Jy?</a> don't address how the size of the source influences the result (if the source is bigger than on beam) nor is the SNR calculation.</p>

CC BY-SA 4.0
2022-08-17T13:44:07.857Z
Does this answer your question? [Converting Jy/beam to Jy?](https://astronomy.stackexchange.com/questions/26721/converting-jy-beam-to-jy)
Prallax
CC BY-SA 4.0
2022-08-17T14:33:22.183Z
Not really no. In this answered is not discussed how the size of the source influences the result (if the source is bigger than on beam). Also there is no question of SNR computation in that question.
Jylu
CC BY-SA 4.0
2022-08-18T01:50:00.293Z
@Prallax it seems not.
uhoh
<observational-astronomy><radio-astronomy><flux>
Source flux in Jy + noise computation, radio astronomy
Jylu
# Source flux in Jy + noise computation, radio astronomy

(Asked by: username_0 on 2022-08-17)

I have an image of an **extended source** obtained with an interferometer (after imaging the uv-data). The image consist of a certain number of pixels, with unit of **Jy/beam**. Somewhere on the image is a source, whose size is greater than my (synthesized) beam size.

1. How do I compute the total flux of the source (**in Jy**!), knowing the flux of each pixels and the area of the beam (in pixels)?
2. How do I compute the corresponding signal to noise ratio (SNR), knowing the standard deviation of the flux of individual pixels (far from the source)?

**Note:** While answers to [Converting Jy/beam to Jy?](https://astronomy.stackexchange.com/q/26721/7982) don't address how the size of the source influences the result (if the source is bigger than on beam) nor is the SNR calculation.

**Tags:** observational-astronomy, radio-astronomy, flux

> **Comments:**
> **username_1**: Does this answer your question? [Converting Jy/beam to Jy?](https://astronomy.stackexchange.com/questions/26721/converting-jy-beam-to-jy)  
> **username_0**: Not really no. In this answered is not discussed how the size of the source influences the result (if the source is bigger than on beam). Also there is no question of SNR computation in that question.  
> **username_2**: @username_1 it seems not.  

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## 0 answers

