In particular , the absence of a clear detection by the Virgo system meant that the source was in one of Virgo 's blind spots ; this fact contributed to considerably reduce the source containment area .
More detailed calculations refined the localization to within 28 square degrees later .
The absence of a clear detection by the Virgo system meant that the source was in one of Virgo 's blind spots ; this fact contributed to considerably reduce the source containment area .
More detailed calculations refined the localization to within 28 square degrees later .