Question: Okay so I am part of two Mage the Awakening 2ed campaigns and the two GM's disagree on the rules for prime sight. What they disagree on is if prime sight is able to see if a mage have active spells.
The rule stats: "... and the presence (if not the composition) of any awakened spell ...".

One of the GMs interpret this as being able to see the spells active in another mages pattern while the other believe it only applies to the spells on objects. Therefore if someone, as an example, has nightvision active (forces dot one spell) another mage with prime sight turned on would or would not be able to see this.

Which interpretation is correct?

Answer: 
**Yes, a mage with prime sight active would be able to see that another mage has a spell active on themselves**

The rules are on page 91. In my opinion, the part you quoted already answers the question. Someone with active prime sight would would at least be able to see that there was an awakened spell affecting the target, even if it was a spell the mage cast on themselves.

I believe expanding the quote removes all reasonable doubt:

> 
> Prime Sight highlights anything the mage can use as a Yantra, and the
> presence (if not the composition) of any Awakened spell or Attainment
> effect.
> 
> 
> 

Note the discussion of seeing attainment effects. While there are definitely exceptions, particularly if you allow in some of the older 1e stuff as expanded material, most attainments only affect the mage and are **generally** harder to detect and with less chance of side effects than spells. If prime sight shows attainments, it makes sense for it to show spells affecting the mage.
In my Opinion, it would be yes.
I also agree with Timothy who answered, If you expand the quote even more with more additional text, it infers that you can detect upon a subject as well, which applies to more than objects since somebody is also able to be considered a subject.

* Highlights anything that can be used as a Yantra
* Detects the presence (if not the composition) of any Awakened spell or Attainment effect
* Detects tass or if a subject has mana
* Detects if they are in a Hallow or Node.
* Prime Knowing/Unveiling Spells that add to Prime Sight (but are separate spells):