You've worked nights, weekends, and all sorts of odd hours to get your payload built up and working-- everything is aligned and functioning like it should, and your instrument is working just as it should. You're getting there, but there are still a few important steps that have to go down prior to launch.
A critical one is integration, where you --well--, integrate your science payload with the other parts of the rocket, provided by NASA through NSROC (Nasa Sounding Rockets Operations Contract). These are systems like power (batteries), guidance (gas jets for navigation, the S19 guidance system) and telemetry (the radios that actually receive your commands in flight and send your data down in real time). Your payload can't just work; it has to work in harmony with these other systems to make sure everything goes exactly as it should in flight.
Integration is also where a lot of the physical testing of the rocket takes place. To fly in a predictable and stable way, the rocket weight needs to be well-known, and it needs its center of gravity to be in a precise, well-defined location. It also spins for stability during launch, so it's got to be balanced in the vertical sense, and you've got to know exactly how hard it is to get it to spin-- this affects how much gas or counterweights you need to get it to spin up or spin down in time for science operations. In space, the rocket will also be moving around and orienting itself-- so you need to know how hard it is to rotate in other axes (pitch+yaw) so you can reliably make those movements with a limited gas budget. Also, how stiff is the rocket? If it's too rigid, it will break at the first sign of stress. But if it's too bendable, it could deform under that same stress. Lastly, can the rocket survive the harsh vibrations of launch and the impact of landing? Integration tests analyze all of these factors and make sure that the rocket passes all tests with parameters are extensively known and fall in the "sweet spots" that are ideal for launch.
Integration is often where you find out exactly what's wrong with the payload, or where the major problems in communication between the NSROC side and the science side exist. The primary integration typically happens at Wallops Flight Facility in Chincoteague, Virginia, with other flight tests occurring just before launch at White Sands Missile Range, NM.
The DEUCE payload integrated before each launch, in August 2017 and November 2018. DEUCE was remarkable because on first turn on... everything worked! That never, ever happens in integration. We were super proud of that, and it's largely a testament to the great work and design of the DEUCE electrical engineer, Nicholas Nell.
See below for pictures of the integration process and various tests.