M4 is the splatter near the center. I "think" the unknown is a bright piece of SH2-9, emission nebula (next to bright star at bottom, Al Nyiat in Scorpius). That's what's labeled that position in Starry Night, though Starry Night doesn't show an image. Antares is the brilliant sun at the top.
If you look really closely, you see the globular NGC6144 at the right angle of a 3-4-5 right triangle with vertices at Antares and M4.
Edited to add: 15 stacked images, skyglow removed with Photoshop: used "dust and scratches" to remove stars and objects from a copy, then subtracted what was left from the image. There was a lot of skyglow otherwise. What was left was dark enough to just linearly add.