The problem is that truth is cognitive. You are claim something you can't perceive with external sensation as out there independent of the mind. The same with things. That is a cognitive concept.
This doesn't matter. As soon as you must admit that the "next capable mind" to encounter the thing would come to the exact same conclusions and measurements - without fail, it is done. The thing is objective. As in, it fits the definition of "objective" that you, yourself provided:
having reality independent of the mind
That explicitly means that it exists regardless whether a mind is there to perceive it or not. You claimed that something being "objective" required a mind, because that is in the definition... which, admittedly, the
word "mind" is, but only in order to demonstrate that the word literally means that no mind is necessary for it to have presence in reality.
Let us start here:
In philosophy, a noumenon is a posited object or an event that exists independently of human sense and/or perception. The term noumenon is generally used in contrast with, or in relation to, the term phenomenon, which refers to any object of the senses.
That is what we are doing. You claim that there are noumenons. Then please point to one.
I already did. The reality of the inner angles of a triangle summing to half a full compliment of the angle represented by a full circle. That is a reality. Again - no triangle capable of existing can break form with this principle. The principle itself exists, even if no one is there to perceive it, utilize it, or think on it. At any time a triangle comes into being, it adheres to this principle - with or without an observer.
I don't have to "hold it in my hand" for it to be true. What a ridiculous thing to insist.
Another "noumenon" that perhaps more readily fits your definition (since it seems to include human sense perception) would be gravity. When we pointed out telescopes at distant stars and saw them all wheeling around one another under the same pretenses of gravitational relationship as the bodies we had observed nearest us, did they all suddenly cover their mouths in surprise and go running into position to make sure that such gravitational relationships appeared coherent to our understanding? Is that how you envision this working? Because that's ridiculous. Point being that the event we've named "gravity" can so obviously be seen to be working, and to the same tune as the objects all around us, even in remote places of the universe where no life is known to be present. And the evidence of gravity having been working throughout time before we were even here is all around us. The shape of the Earth and the other planets that have formed in our solar system, for example. It exists, independent of any mind, and should rightfully be assumed to exist even if none of us are here... because again, all evidence points to it having existed far prior to the first human who could articulate the relationship to another human or himself/herself.