Long March 2C with a Yuanzheng-1S upper stage launched Shiyan-33 from Jiuquan at 12:11 Beijing time on 27 March 2026. CASC confirmed that the satellite reached its planned orbit. The announced purpose is scientific experimentation in space-environment detection. The release did not specify a complete instrument list or measurement performance, and launch success is not presented as completion of the science programme. The configuration adds a liquid-propellant upper stage to the two-stage Long March 2C, supporting different orbits and single- or multi-satellite deployments. A published capability of 2.5 tonnes to a 700-kilometre Sun-synchronous orbit is a configuration performance figure, not a statement of this satellite's actual mass or altitude. The mission was the 635th Long March flight. Subsequent scientific results require their own formal evidence. Source photographs are not reused without confirmed rights.