How does a character know the intensity or level of a magic aura?

On p. 157 of the 5th edition, there is a level 2 spell that appears to give binary information (there is or there isn't an aura), and maybe someone with the virtue Magic Sensitivity might be able to discern the magnitude of an Aura (but that isn't explicit). On p. 184 the rules provide a description of magic auras as making colors more intense, etc. But again, no details on how to determine the magnitude of a magic aura.

I cannot discover in any edition of the rules a straight-forward method for a character to find the level or magnitude of a magic aura.

How, for example, do magi decide where to place a covenant? Of course I could devise a new spell, but is there anything I'm missing?

I think this is an intentional omission. If you give characters a method of determining exactly how strong an aura is, you'll be injecting a game mechanic into character conversations. Having players discuss aura levels is fine, but having the characters do it takes away from the suspension of disbelief that must take place in a game. That's why characters talk about magnitudes instead of spell levels.

Rather than having the characters going around looking for a 5+ aura to start their covenant in, the Storyguide and the players should discuss what level aura they want to have and then trust the storyguide to match the story to the group's concept. The covenant creation rules are based on the premise that it should be a collaborative effort.

I would like to consider beginning a campaign with the characters investigating possible covenant sites.

There could also be a situation where a party might want to acomplish some magical task while "on the road": a task that is just beyond their current abilities but might be possible to do if they could find a magic aura for a boost.

I certainly agree that in-character conversations of "level 3" or "level 6" are inappropriate, but "This aura is as strong as what I experienced while at Harco!" wouldn't be.

Here's a spell I just found on the web
(http://xavier.edd.bertou.online.fr/Ars-Mag/grimoire/node57.html#SECTION000112000000000000000):

Siren Call of the Magus' Home ... In Vi - 20
R ... Portée : Area ... Durée : Nap ... Im
The caster of this spell can ``hear'' any place within 10 miles that has a magical aura as [a] strange, alluring melody. Since magical auras are so rare, this is of considerable help when magi are trying to find a place for a new covenant. The stronger the aura, the more beautiful the music, the nearer the aura, the louder the music.

***
This is pretty much what I was looking for, only more elegant than I expected! Sorry to bother folks.

//I cannot discover in any edition of the rules a straight-forward method for a character to find the level or magnitude of a magic aura.//

There is a very easy way to do that, once you know (e. g. by casting InVi spells) the type of an aura you are in.
You just cast trivial non-fatiguing spontaneous spells (no dice or risk involved) and see whether you succeed or not: since the aura influences your casting score and you know all its other components, you can derive something on the strength of the Aura from whether you succeed or not.

There is also (see ArM5 p. 158) the level 2 InVi base effect (R: Per, D:Mom, T:Ind) 'determine the power of a mystical aura', so a spell or spontaneous effect like

A Tongue for Power InVi2 (R:Per, D:Mom, T:Taste)

tells you how powerful the aura you are in tastes, and

An Eye for Power InVi 10 (R:Per, D:Mom, T:Vision)

tells you - e. g. through brightness - the power of an aura you can see.

At least for faerie and magical auras the above trick and spells should be all you need.
For divine or infernal auras the information gained by them may depend on the particular aura or campaign.

Kind regards,

Berengar

Thank you for pointing out that note on p. 158. I missed it.

But it brings up a trivial question: On p. 156 there is a spell of level 2 (I mention it above) which detects the presence of an aura, while in the note you just pointed out, that effect is described as being level 1. No big deal, however.

"But it brings up a trivial question: On p. 156 there is a spell of level 2 (I mention it above) which detects the presence of an aura, while in the note you just pointed out, that effect is described as being level 1. No big deal, however."

+1 Magnitude for touch effect on that spell, isn't it? That would bring the total to 2.

"+1 Magnitude for touch effect on that spell, isn't it? That would bring the total to 2."

I am not familiar enough with the new rules to understand that.

//On p. 156 there is a spell of level 2 (I mention it above) which detects the presence of an aura, while in the note you just pointed out, that effect is described as being level 1. No big deal, however.//

Sense of Magical Power InVi2 (R:Touch, D:Mom, T:Ind) is just not quite optimized.

You can also determine the presence of a type of mystical aura you are in by taste.

That would be:

InVi 1 (R:Per, D:Mom, T:Taste) Taste the Salt of Magic, Taste the Faerie Vinegar, Taste the Sweetness of Heaven, Taste the Bitterness of Hell

Argument for the level:
Base effect 1 (detect the presence of a mystical aura)
You yourself get the new sense (ArM5 p.114)
The sense activates only for a moment
And T:Taste is equivalent to T:Ind (ArM5 p.114, too)

Now you can speculate about why the 'Sense the Taste of ...' spells did not become popular enough in the Order to replace the less efficient 'Sense of ... Power' variants. Were the surprised expressions of Magi tasting a really strong faerie vinegar just too undignified?

Kind regards,

Berengar