The bursts are extremely short (roughly a millisecond long), so there's not enough time to point a telescope in the right direction. So far the discoveries of

The bursts are extremely short (roughly a millisecond long), so there's not enough time to point a telescope in the right direction. So far the discoveries of these fast radio bursts (FRBs) have been serendipitous. Based on the observed number of FRBs it's estimated that there are about ~2500 per day that would be detectable by a telescope pointed in the right direction. Here's a paper that goes into that estimate in much more detail: http://adsabs.harvard.edu/abs/2015MNRAS.447.2852K http://adsabs.harvard.edu/abs/2015MNRAS.447.2852K