You would be able to use the EOS Rebel T3 to take night time exposures. You simply set it up on a tripod, lock it in place and use the BULB setting while the camera is in Manual.
This [the Bulb setting] will let you hold the shutter open as long as you wish. To avoid camera shake you may want to use a remote to trigger the shutter, such as RS-60E3. If you are using an Image Stabilized lens, be sure to deactivate the IS function.
The idea of a tripod is essential; About the expousure, you need to decide between expousure and the aperture of the diaphragm and make a kind of "perfect mix", in this way you could capture all the light... I think the only way to know it is to try a few times.
12/05/2023: New firmware updates are available.
09/26/2023: New firmware updates are available.
08/18/2023: Canon EOS R5 C training series is released.
07/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
03/30/2023: New firmware updates are available.