system
Given the following post, respond as if you're commenting on Reddit:
human
How bright would Andromeda be if it were a quasar?
gpt
A quasar is maybe 1,000 times the brightness of Andromeda or the Milky Way, and all the brightness is concentrated in the centre around the supermassive black hole.

Currently, Andromeda as a whole has an apparent magnitude of 3.44, which means that the total brightness of the whole thing is about as bright as a fairly moderate star in the night sky. If there was a central point that was 1,000 times brighter, that point would have an apparent magnitude of about -4.

Apparent magnitude is a backwards scale where lower numbers are brighter. The brightest star in the sky has an apparent magnitude of -1.46. Venus goes up to -5 at its brightest, and down to about -3 at its dimmest. Mars and Jupiter are about -3 at their brightest. The International Space Station goes up to -5.9, because it's so close. A full Moon is about -13, and the Sun is -27.

So what we would see is a bright point of light, about the brightness of Venus, in the middle of the Andromeda galaxy. This would be bright enough to see even when the sun is up, at least during sunrise and sunset.