Enter the observed irradiance and the reference flux into the Calculator. The calculator will evaluate the Apparent Magnitude.

## Apparent Magnitude Formula

M = -5*log(10) (Fx/Fx0)

Variables:

- MI is the Apparent Magnitude (())
- Fx is the observed irradiance
- Fx0 is the reference flux

To calculate Apparent Magnitude, divide the observed irradiance by the reference flux, take the log of the result, then multiply by -5.

## How to Calculate Apparent Magnitude?

The following steps outline how to calculate the Apparent Magnitude.

- First, determine the observed irradiance.
- Next, determine the reference flux.
- Next, gather the formula from above = M = -5*log(10) (Fx/Fx0).
- Finally, calculate the Apparent Magnitude.
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem : **

Use the following variables as an example problem to test your knowledge.

observed irradiance = 101

reference flux = 6

## FAQs

**What is the difference between Apparent Magnitude and Absolute Magnitude?**

Apparent Magnitude measures how bright a celestial object appears from Earth, while Absolute Magnitude measures the intrinsic brightness of an object, assuming it is placed at a standard distance of 10 parsecs from the observer.

**Why is the logarithmic scale used in the Apparent Magnitude formula?**

The logarithmic scale is used because the range of brightness in the universe is vast. A logarithmic scale allows us to compress this range into a more manageable scale where a difference of 5 magnitudes corresponds to a brightness factor of 100.

**Can the Apparent Magnitude be a negative value?**

Yes, the Apparent Magnitude can be negative. Objects brighter than the defined zero point of the scale, such as the Sun, Venus, and Sirius, have negative magnitude values.

**How does the observed irradiance affect the calculation of Apparent Magnitude?**

The observed irradiance directly influences the Apparent Magnitude calculation. A higher irradiance indicates a brighter object, leading to a lower (potentially negative) magnitude, while a lower irradiance indicates a dimmer object, resulting in a higher magnitude value.