Hi to everyone,

in this youtube video at approxymately 6min00sec:

https://tinyurl.com/y2ahf6bs

he explains that it took Edwin Hubble between 30 and 50 hours of exposure time to get a single spectrogram showing the radial velocity of a galaxie.

Does someone know how much exposure time it takes today with modern technologies?

And also, is it the same exposure time required for quasars?

I'm really interested in the details of how astronomer measures redshifts. There are a lot of general videos on the subject but I didn't find any that goes in the details of how astronomers actually performs the measure.

regards,