Quasars are active galaxy cores. One can not differ them from "normal" stars except one checks their spectrum being literally shifted to the red. This is a doppler effect and we call it Redshift.
Two Quasars are visible in the photo above:
- Quasar RX J121803.82+470854.6 with a magnitude of 21.04 mag and a redshift of z=1.743
- Quasar SDSS J121732.69+465829.3 with magnitude of 18.4 mag and a redshift of z=1.99071