Broken RecordG 15

To unlock the hidden song you need to shoot 15 Astronauts in the following locations:

#1 Under the staircase between spawn and the Water Treatment plant
#2 On the Top-left of the Cargo Bay Ceiling
#3 In a grate in the big hallway near the Proteus wallbuy
#4 At the very bottom of the pit by Tuff 'Nuff
#5 In the bottom left hand corner of the barrier near N31L's head
#6 Under the staircase to the left of Bombstoppers
#7 By a pole outside of the map behind Change Chews
#8 In a window on the building across the Pack-a-Punch portal
#9 On top of glacier to the left of the Pack-a-Punch portal
#10 On a ledge outside of the map by the Pack-a-Punch portal
#11 Inside the bathroom trash can within the theater
#12 Inside the barrier by Racin' Stripes
#13 Inside the ticket booth in front of the theater
#14 Top balcony in the fire escape outside of the theater
#15 Inside the vent above red hallway

This is the video I used to get the song, be careful tho as the achievement sometimes doesnt pop and you have to redo it.
https://www.youtube.com/watch?v=c8gQZwqxA5c&t=196s