C9 was largely dedicated to a search for gravitational microlensing events in a region around the Galactic bulge. A variety of other targets were also observed through the K2 Director's Discretionary Target program. These include O-type stars,the Kuiper Belt Object Quaoar, and the Lagoon star-forming region (M8). The complete list of observed targets can be found here.
Due to the unique operations for this campaign, the C9 data release only contains Type-1 target pixel files and does not include light curves. Also, the campaign was split into two halves (C9a and C9b), with a data downlink taking place in between C9a and C9b to maximize data collection capabilities as well as introduce a ~0.6 pixel offset. Archive products are therefore identified as being from either C9a or C9b using the identifier c91 or c92, respectively. We strongly encourage users interested in C9 data to review the data release notes in detail.