There is nothing I know of astronomically speaking that can be called a hypernova.
Nova: The explosion resulting from the birth or some death's of a star where sufficient gravitational force causes the star's matter to ignite or in instances of death where sufficient inward pressure causes the star to bulge and thus to cool and die.
Supernova: The explosion resulting from the death of a star where sufficient mass is built up to cause the interior temperatures to create enough pressure that, as enough of the stars mass is burnt off, it bursts apart from within while still burning.
In novae, gases and surrounding clouds may become illumined, and these nebulae are called 'star factories' as their dust combines to form stars. In supernovae, outward jets and thrusts of gas can exceed several million miles per second in speed because of the tremendous force.
Astronomically, the only things more powerful than supernovae are blackholes, quasars, pulsars, and galactic cores (which are theoretically blackholes).
Quasars have constant jets of gas that create the appearenc of a pole running through them, jetting out in two directions constantly. They are many times larger than stars and if one exploded, the resulting force would outmatch a supernova several hundred times. However, it isn't possible for a quasar to explode because enough pressure never builds up. Pulsars emit bursts of gas in brilliant flashes for one or two seconds every one or two seconds. This gives them the appearence of flashing from a distance. These constant releivings of pressure make it entirely improbable for one to explode.
A nova within visibility of our technology will only occur once every thousand years or so. A supernova will only occur once every million years. No one has ever seen either a quasar or pulsar explode.
In theory, a blackhole could explode. A blackhole is simply a mass of matter that is so increadibly dense that the gravity it creates pulls inward with such unprecedented force that even light cannot escape. The gravity of a blackhole is powerful enough to hold entire galaxies, such as our own (being 160,000 light years from edge to edge) together. Because of ionization and a bunch of other atom-stripping things that go on inside blackholes (and stars, for that matter), matter takes on pure properties. This means that every atom is broken apart into ions, simply the pieces of atoms. This very pure matter can be condensed into very small spaces because the distance between the nucleus of an atom and it's electron shell is no longer existant. Thus, all the matter of a blackhole can exist in a relatively small space. No one really knows why, but somewhere in the middle of burning itself to a crisp and ionizing atoms, blackholes don't quite have it in them to explode. If they did, the force would be sufficient to literaly tear our galaxy apart. If Earth, for example, were to be put ten million kilometers from a blackhole, it would be pulled inwards and disintegrated entirely in about one second. I suppose this could be where your hypernova is coming from, it could also be one of the other astronimical phenomenon discovered. However... from Earth and our imaging devices we can see thousands of galaxies, we can take pictures of every part of our galaxy. We can count the quasars and pulsars in our local cluster of galaxies (there aren't very many). In the near future we will be able to count the stars in our galaxy and chart the arms. If any one of these very large astronimical phenomenon were to explode, it would mean more to many scientists than almost anything else. I doubt it would go unherd of by most people, especially those with an interest in space.
My guess is that 'hypernova' is someone's synonym for 'supernova' who doesn't know that a supernova is more powerful than a nova and is mistaking it for being a nova.