<p>I can't seem to find data about surface magnitude of galaxies in Simbad.
I can easily find the apparent and absolute magnitude ...
Should I just try to compute the surface magnitude, given the apparent magnitude, and galaxy diameter (arc sec)?
Do you know how to find surface mag in Simbad, or NED , Vizier?</p>
<p>Will this give a reasonable estimate?:</p>
<pre><code>SurfaceB = m + 2.5 * log10(AngularArea)
</code></pre>
<p>Aproximate Angular Area:</p>
<pre><code>AngularArea = pi * (galaxyDiameter/2)^2
</code></pre>

CC BY-SA 4.0
2022-08-16T00:05:11.610Z
The reason there is no surface magnitude is due to the difficulty in defining it. A galaxy will have a bright core, and fade out to nothing, with features of various brighness in between.
Greg Miller
CC BY-SA 4.0
2022-08-16T08:34:37.040Z
Ok, so I figure it's better to calculate a rough estimate
Adrian
<star-catalogues><simbad>
Simbad, NED databases surface magnitude data?
Adrian
# Simbad, NED databases surface magnitude data?

(Asked by: username_0 on 2022-08-15)

I can't seem to find data about surface magnitude of galaxies in Simbad.
I can easily find the apparent and absolute magnitude ...
Should I just try to compute the surface magnitude, given the apparent magnitude, and galaxy diameter (arc sec)?
Do you know how to find surface mag in Simbad, or NED , Vizier?

Will this give a reasonable estimate?:

```
SurfaceB = m + 2.5 * log10(AngularArea)

```

Aproximate Angular Area:

```
AngularArea = pi * (galaxyDiameter/2)^2

```

**Tags:** star-catalogues, simbad

> **Comments:**
> **username_1**: The reason there is no surface magnitude is due to the difficulty in defining it. A galaxy will have a bright core, and fade out to nothing, with features of various brighness in between.  
> **username_0**: Ok, so I figure it's better to calculate a rough estimate  

---

## 0 answers

