<p>No, Cal Day is entirely different. </p>
<p>CalSO is orientation for new students, happens over the summer, you also meet with advisors and register for classes.</p>
<p>Cal Day is during the year and is an annual showcase for Cal to the local community, to alumni, to parents, to anyone curious about the school. Alumni show up to meet each other, that is the reception part you saw. However, it is totally unconnected to CalSO, they just mentioned it because it is an earlier chance to visit, just like the overnight stay programs, which also have nothing to do with calSO.</p>