<p>The absolute peak magnitude of type 1a supernovae is to some degree correlated with the decay time of the supernova light curve. The <a href="https://en.wikipedia.org/wiki/Phillips_relationship" rel="nofollow noreferrer">Phillips relationship</a> says that the peak absolute magnitude in the blue (B) region of the spectrum is</p>
<p><span class="math-container">$$M=-21.726+2.698\cdot \Delta m$$</span></p>
<p>where <span class="math-container">$\Delta m$</span> is the observed decline of the B-magnitude 15 days after maximum.</p>
<p>With the observed apparent magnitude <span class="math-container">$m$</span> you have then the <a href="https://en.wikipedia.org/wiki/Distance_modulus" rel="nofollow noreferrer">distance modulus</a> <span class="math-container">$m-M$</span> and thus the distance <span class="math-container">$d$</span></p>
<p><span class="math-container">$$d=10^{1+(m-M)/5} \ \mathrm{Parsecs}$$</span></p>

CC BY-SA 4.0
2022-01-31T19:05:09.630Z
2022-01-31T23:04:13.190Z
2022-01-31T23:04:13.190Z
Thomas
<p>This is for a project in astronomy with extensive data analysis. How should I calculate the distance of galaxies using AGN and supernova Ia? I am using the data from dr17 of SDSS.</p>

CC BY-SA 4.0
2022-01-31T18:19:10.930Z
What have you already tried? Type Ia have absolute magnitudes of -19.3, so you probably could use inverse square law given you have magnitude of the Ia in said galaxy.
WarpPrime
CC BY-SA 4.0
2022-01-31T19:18:52.417Z
@fasterthanlight But who ever has that information?
zephyr
<distances><supernova><python>
How to calculate distance to other galaxies using type 1a supernova?
Nabiha Nadeem
# How to calculate distance to other galaxies using type 1a supernova?

(Asked by: username_0 on 2022-01-31)

This is for a project in astronomy with extensive data analysis. How should I calculate the distance of galaxies using AGN and supernova Ia? I am using the data from dr17 of SDSS.

**Tags:** distances, supernova, python
> **Comments:**
> **username_1**: What have you already tried? Type Ia have absolute magnitudes of -19.3, so you probably could use inverse square law given you have magnitude of the Ia in said galaxy.  
> **username_2**: @fasterthanlight But who ever has that information?  

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## 1 answers

### Answer by username_3 on 2022-01-31. Score: 2

The absolute peak magnitude of type 1a supernovae is to some degree correlated with the decay time of the supernova light curve. The [Phillips relationship](https://en.wikipedia.org/wiki/Phillips_relationship) says that the peak absolute magnitude in the blue (B) region of the spectrum is

$$M=-21.726+2.698\cdot \Delta m$$

where $\Delta m$ is the observed decline of the B-magnitude 15 days after maximum.

With the observed apparent magnitude $m$ you have then the [distance modulus](https://en.wikipedia.org/wiki/Distance_modulus) $m-M$ and thus the distance $d$

$$d=10^{1+(m-M)/5} \ \mathrm{Parsecs}$$


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