amateur observing - What was the flash I saw in the night sky?

On Saturday night (April 2nd) in Sydney, Australia, somewhere between 8:30 PM and 9:00 PM my partner and I saw three flashes in the sky. We were looking at Jupiter through a pair of 7x50 binoculars and I saw the first one just slightly above the planet. My partner, without binoculars, saw nothing and I thought it had been a trick of the light.

But, about 10 minutes later, she was looking through the binoculars and saw a flash as well, that time a little to the left of Jupiter. Another few minutes later she saw it again and then said she saw something moving extremely fast towards the horizon (faster than the satellites I often witness that look like slow moving stars). I was looking in the right area, but could see nothing without the binoculars.

The flash was only in a small area, a little larger than a pinhead, not across the whole sky.

What could these flashes have been?