TESS-SIP creates a Systematics-insensitive Periodogram (SIP) using lightkurve (ascl:1812.013) to detect long period rotation in NASA's TESS mission data. The SIP method detrends telescope systematics (the TESS scattered light) simultaneously with calculating a Lomb-Scargle periodogram, thus allowing estimation of the rotation rate of variables with a period of >30 days when there are multiple sectors.