Hey do you have some Lucy and Jellal hcs regarding Urano Metria and Grand Chariot? Sorry to bother :)
Grand Chariot directly makes the asterism (pattern) for the Big Dipper and Urano Metria itself calls on all 88 constellations in the sky, which is a big reason why I know for a fact that Heavenly Body and Celestial Magic have the same origins; most likely what happened is they used to be under the same type of magic but, over the course of hundreds of years, they branched out into separate things, and while they both still lie heavily in astronomical objects, Jellal's Heavenly Body is a "jack-of-all-trades" variation that covers a bit of everything with a focus on offensive spells while Lucy's Celestial variation focused specifically on the stars and planets, being a support based magic as the caster themselves would not usually be the one fighting (hence why Lucy is such an oddity among her fellow mages)
Basically, Jellal could not use Urano Metria, because he has no direct connection to the Zodiacs but Lucy could, if he taught her and she was strong enough, use Grand Chariot because it's connected to the Big Dipper ("Grand Chariot" is the french name for it in fact) which is the asterism for the Ursa Major constellation
And so Lucy and Jellal would be big astronomy nerds together actually and Erza would sit there with massive heart eyes listening to them speak what sounds like absolute gibberish to her own ears
