Constellation Celebration

In honor of this celebration, 13 new constellations have been identified!
Assign their names and assemble them into a starfield to find out what we're celebrating.
(This puzzle is also available as a PDF file. But if you print it, it will use a lot of blue ink. Sorry about that!)

CNTV
CONJOINED
GALACTIC
INDEMNIFY
KAVA KAVA
MAMMOTH MTN.
MUNTZ
SHINY DIAMOND
SMIRK
SPARKS, NV
WARMTH
WAX CANDLE
WILLOWY
γ7 δ3 β9 ε4 α5 Total brightness: 7 α7 β5 ε6 ζ4 δ7 γ7 Total brightness: 9 γ2 α4 δ7 β4 ε2 Total brightness: 5 δ4 γ4 ε9 ζ3 α4 β2 Total brightness: 8 γ3 δ7 β2 α1 Total brightness: 4 β8 γ1 δ3 α1 Total brightness: 5 β3 ζ4 δ2 γ1 ε7 α4 Total brightness: 9 α9 δ2 β5 γ1 ε2 Total brightness: 8 ε1 γ1 δ7 β5 α4 η1 ζ2 θ2 Total brightness: 12 α4 β5 δ1 γ5 Total brightness: 6 γ1 ε2 δ1 α7 β2 Total brightness: 8 α1 ε7 γ2 δ2 ζ4 β5 Total brightness: 9 γ2 δ1 β7 η9 ε4 ζ7 α0 θ6 Total brightness: 10

Feel free to email me if you need hints. Or read the full solution.