The Noble and Most Ancient House of Black has a unique trait, and that's all their family members having astral names—and the occasional moon crater or asteroid or something.
Of course, you don't need to do that—it can be something else as long as it fits with in the "Black" style, like Phineas or Narcissa (fancy, unheard of, etc).
I compiled a list here of certain constellations and stars that haven't yet been used as Black names (I think).
Altair
The brightest star within Aquila
Antlia
"The Air Pump"
Aquila
"The Eagle"
Ara
"The Altar"
Auriga
"The Charioteer"
Caelum
"The Chisel"
Canopus
The second brightest star in the sky, found in Carina
Capella
Sixth brightest star in the sky; found in Auriga
Carina
"The Keel"
Cepheus
or Cephei, I guess
Corvus
"The Crow" / "The Raven"
Fornax
"The Furnace"
Lacerta
"The Lizard"
Leo
"The Lion"
Lyra
"The Lyre"
Norma
"The Rule"
Perseus
Ancient Greek hero
Procyon
Eight brightest star in the sky, found in Canis Major
Rigel
Seventh brightest star in the sky, found in Orion
Vega
Fifth brightest star in the sky, found in Lyra
Vela
"The Sails"
