UK Astro Imaging - Sky Quality Register
Magnitude Guide

Magnitude 1
You can only see the top left (Betelgeuse) and bottom right (Rigel) stars in Orion.

Magnitude 2
You can now see the top right star (Bellatrix) and also the left (Alnitak) and middle (Alnilam) stars of Orions belt.

Magnitude 3
You can now see the bottom left star (Saiph), the right hand star (Mintaka) of Orions belt and also one star of Orions sword.

Magnitude 4
You can now see another star just below Alnitak, the left hand star of Orions belt.

Magnitude 5
You can now see three apparent stars of Orions sword.

Magnitude 6
You can now see more stars along Orions belt and Orions sword is clearly visible.

Magnitude 7
You can now see many stars in Orion and may even be able to see a gaseous object (M42 nebula) in Orions sword.

 

The Orion Constellation

The lower part of Orion